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Protoz: an Parasitism of the Alimentary Tract :
PatJiolo(j\\ Diagnosis and Treatment. By Kenneth ^^

M. Lynch, pp. xvii + 256. $3.75. 1930. The cd

Macmillan Company. ^.

Doctor Lynch has written a handy hook for a>

medical students, practitioners, and others con- ^^

nected with medicine in special ways that make o P^

them responsi1)le parties in the diagnosis, treat- [^

ment, and prevention of protozoan infections. q p

The author's aim to write an eminently practical ^

treatise has led him to omit, insofar as possible,
•tU technical details land controversial questions ^^P ^i)
that mi,s:ht serve to confuse the medical man who ^^^
has had little or no training in Protozoology. Pos~ ti^l^;
Ki1)ly he has gone a l)it too f,ar in this regard, es- ^2-
r^ecially in the introductory chapters. However, ^ 3
nmple references to the standard treatises as well ^
as to special papers are given, and to some of
these the reader undoubtedly will wish to refer H
when he has finished Doctor Lynch's outline. The ^
book should prove, for the audience to which it H
is addressed, not only thoroughly useful but also
thought-]3rovoking. — L. L. Woodruff.

PROTOZOAN PARASITISM OF THE
ALIMENTARY TRACT

Pathology, Diagnosis and Treatment

THE MACMTLLAN COMPANY

NEW YORK - BOSTON • CHICAGO • DALl VS
ATLANTA • SAN FRANCISCO

MACMILLAN & CO., Limited

LONDON • BOMBAY • CALCUTTA
MELBOURNE

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^^ /^

PROTOZOAN PARASITISM

OF THE

ALIMENTARY TRACT

Pathology, Diagnosis and Treatment

BY

KENNETH M. LYNCH, m.d.

PROFESSOR OF PATHOLOGY, MEDICAL, COLLEGE OF THE

STATE OF SOUTH CAROLINA, CHARLESTON,

SOUTH CAROLINA

NEW YORK
.THE MACMILLAN COMPANY

1930

Copyright, 1930,
By the MACMILLAN COMPANY.

All rights reserved — no part of this

book may be reproduced in any form

without permission in writing from

the publisher.

Set up and electrotyped. Published November, 1930.

PRINTED IN THE UNITED STATES OF AMERICA '

TO
JUANITA KIRK LYNCH

PREFACE

Eighteen years ago, when my interest in the pro-
tozoa of the alimentary tract of man was first aroused
by my former chief and lamented teacher, the late
Professor Allen J. Smith, of the University of Penn-
sylvania, there was but little actual knowledge con-
cerning them in the possession of the medical profes-
sion.

In fact the whole subject of the relations existing
between man and these lower animals, particularly
in regard to the effect of the parasite upon the host,
and, also, in reference to the relation of these pro-
tozoa of man to similar species in other animals,
was in a state of confusion.

There had been, prior to that time, excellent work
done in the subject, in fact, on the average, probably
of better calibre than that of more recent studies, but
it had not reached the stage of useful information
available to the medical world.

Existing knowledge of protozoa in general was in
the hands of a few men, biologists, or buried in scien-
tific literature not available except by particular
search ; and the interest of the medical world in the
matter had not been aroused. The conception of the
protozoa of the alimentary tract, and of the nature of

viii PREFACE

their parasitism, in the minds of physicians in gen-
eral was hazy indeed. Intestinal protozoa were
parasites to be gotten in the tropics, the produc-
ers of amoebic and other tropical dysenteries. An
amoeba was an amoeba and a flagellate was a ^'cer-
comonas" ; most of the species now of familiar names
were unknown to them, some were unrecognized by
anyone.

Since that time, perhaps due largely to the in-
terest incident to the world war and the care of large
bodies of troops and other people, but primarily due
to the persistent efforts of a few whose interest and
knowledge in this field came into play under the con-
ditions of war organization, the whole subject has
come into general prominence. Much valuable in-
formation has been added by careful scientific in-
vestigators, but a great deal of undigested writing,
especially by physicians who have not had particular
regard for scientific methods, has been done. Con-
sequently there exists considerable chaff with the
grain, and the medical profession has been fairly
confused by it.

During recent times there have been published sev-
eral excellent books which cover the field in various
fashions, such as Wenyon's Protozoology, Calkin's
Biology of the Protozoa, Craig's Parasitic Protozoa
of Man, Human Protozoology by Hegner and Talia-
ferro, Chandler's Animal Parasites and Human Dis-
ease, The Intestinal Protozoa of Man, by Dobell and
O'Connor, and others, to which works the author re-
fers those who desire biological information beyond

PREFACE ix

the scope of this book and bibliography not directly
referred to here.

Most of the above mentioned works, excellent as
they are, are difficult for any except those with a
fair knowledge of the subject already and the most of
them are of more service to biologists than to prac-
titioners in preventive and curative medicine.

The confusion w^hich still exists, almost as great
as ever among those most practically concerned with
the subject, has been the stimulus in attempting
this book.

It has been planned as a monograph for students
and practitioners of medicine and for those variously
connected with medicine in special ways which bring
them as responsible parties into this very common
consideration in the diagnosis, prevention and treat-
ment of disease in man.

It is not intended for protozoologists, save as a
connecting link between their science and medicine.
To biologists it will be an unconventional book. It
is purposely so. Technical details which tend to con-
fuse and so lose the interest of those to whom they
are of no concern are largely left out of considera-
tion.

To many medical practitioners it will probably be
a radical book. In my several years of experience as
a sort of a go-between in protozoology and medicine
I have come to some very definite opinions as to cer-
tain practices in medicine which are difficult to jus-
tify. These conclusions may not be agreeable to
certain practitioners.

X PREFACE

To those physicians who diligently and honestly
endeavor to do their full duty by their patients but
who are widely and frankly confused as to what to do
and when to do it when they are confronted with the
finding of one or more of these organisms in an unwell
person, I hope this book may be of some assistance.

To those who have become blinded by false report
or faulty or inadequate observation, I hope it will
bring serious reconsideration on the basis of the
scientific method.

To those laboratorians connected with the medi-
cal profession as technical assistants I hope it may be
of use in studying the several protozoa of this system
which they are commonly called upon to identify.

The author desires to express his thanks to the
Curator of the U. S. Army Medical Museum and to
Major G. R. Callender for the use of certain photo-
graphs, which are noted in their titles as having
come from the Museum, and to Dr. W. M. James, of
Panama, and others whose material has been freely
used. Appreciation is also expressed to Mr. J. M.
Hicks, a student at this College, for his assistance in
making the drawings for some of the illustrations,
which drawings were not usually made from indi-
vidual specimens of the various organisms but are
mainly conceptions as set down for him by the author
from study of actual specimens, usually a great num-
ber, assisted by the conceptions of other workers in
this field of protozoology.

KENNETH M. LYNCH.

Charleston, S. C.

CONTENTS

PAGE

Introduction c c xv

CHAPTER

I. The Life of Protozoa . . . . 1
History and General Considerations.
Anatomy and Physiology. Characteristics
of Cysts. Life History. Specificity of
Parasite for Host. Resistance and Lii-
munity of Hosts. Encystment. Repro-
duction.

II. Dissemination and Prevention of In-
fection ....... 22

HI. The Amoebae 30

Classification. General Considerations
and Morphology. Methods of Examina-
tion for Amoebae.

IV. The Amoebae (Continued) .... 44
Endamoeba histolytica. Prevalence, Dis-
tribution and Transmission. Experimental
Information. Cultivation. Habitat and
Effects. Chronic Intestinal Amoebiasis.
Acute Amoebic Colitis (Amoebic Dysen-
tery). The Stools of Dysentery. Treat-
ment.

V. The Amoebae (Continued) .... 94
Endamoeba coli. Morphology. Preva-
lence and Importance. Habitat and Ef-
fects. Councilmania lafieuri.
xi

37 f^"/

xii CONTENTS

CHAPTER PAGE

VI. The Amoebae (Continued) .... 105
Endamocha gingivalis. History and Rela-
tion to Pyorrhoea Alveolaris. Morphology.
Habitat and Effects. Experimental In-
formation. Prevention and Treatment.

VII. The Amoebae (Continued) . . . .117
Endolimax nana. lodamoeba butschlii.
Dientamoeba fragilis. Other Amoebae.

VIII. The Flagellates 125

Classification. General Considerations.
Prevalence and Relations. Examination
for Flagellates.

IX. The Flagellates (Continued) . . . 139
Trichomonas Species. Cultivation. Tri-
chomonas hominis. Prevalence and Rela-
tions. Habitat and Effects. Treat-
ment. Other Intestinal Trichomonads.

X. The Flagellates (Continued) . . . 157
Trichomonas elongata. Relations. ]\Ior-
phology. Habitat and Effects. Treat-
ment.

Trichomonas vaginalis. Prevalence.
Transmission, Habitat and Effects. Treat-
ment.

XI. The Flagellates (Continued) . . . 169
Chiloniastix mesnili. Prevalence. ]\Ior-
phology. Cultivation. Transmission,
Habitat and Effects. Treatment.
Giardia intcstinalis. Examination for
Giardia. Morphology. Habitat and Ef-
fects. Treatment. Tricercomonas intesti-
nalis. Enteromonas hominis. Embado-
monas intcstinalis .

XII. The Ciltates 196

Classification. General characteristics.
Balantidiuni coli. Prevalence. Trans-
mission. Morphology, Habitat and Ef-

CONTENTS xiii

CHAPTER PAGE

fects. Balantidial Dysentery. Chronic
Balantidiosis. Treatment. Balantidium
mimitum. Nyctotherus baba.

XIII. The Coccidia 216

Classification. General Considerations.
Life history. Habitat and Effects. Isos-
pora belli. Isospora hominis. Eimeria
gubleri.

XIV. Blastocystis . . - , , . 230

References 235

Index 251

INTRODUCTION

The problem of the status of the protozoa of the
ahmentary tract in relation to health and disease is
of great medical and economic importance.

When we consider the great and world-wide prev-
alence of this class of parasites, the great number of
people who are not in good health who carry one or
more of species of these organisms, the great number
of people who are being treated by physicians over
extended periods of time with the finding of intes-
tinal protozoa as the basis of treatment, the subject
becomes of large proportions and of great consequence
to the public of the world. This is a responsibility
which the author w^ould bring to the medical profes-
sion.

The second responsibility which belongs to them
in the matter is this. The search for and identifi-
cation of alimentary tract protozoa in the practice of
medicine, as done in this country outside of recognized
medical centers, is largely in the hands of unquali-
fied people.

To many people who assume the responsibility for
identifying protozoa in the feces and of playing some
part in^ evaluating their relations to disease, that
all-important body, the protozoan cyst, is an un-

XV

xvi INTRODUCTION

recognized object. I believe that it is no exaggera-
tion that many have not consciously observed a pro-
tozoan cyst, many are unable to differentiate the
several species when they see them, and not a few
are unable to differentiate that common organism,
Blastocystis, from them.

In a great many instances the finding of an
amoeba in the stool has furnished, per se, a diagnosis
of intestinal amoebiasis. Correct identification of
the amoeba is comparatively seldom done.

The finding of a free swimming form leads to a
report of a flagellate, without much regard to the
species. All are Trichomonas or "Cercovionas'' to
many medical laboratorians and practitioners.

These practices are to some extent a convenience.
When the finding of protozoa fits with clinical ideas,
or when nothing else is found as a basis for the ill-
ness, or, in the hands of many physicians, regardless
of other conditions, the parasite is made the basis
of therapeutic attack.

Many patients have been and are now under treat-
ment for intestinal amoebiasis who have had no path-
ogenic amoeba. Many people have been and are
now under treatment for ^'flagellosis" whose flagel-
lates are not concerned in their illness or, literally,
about the treatment.

Protozoologists as a rule are not pathologists;
few pathologists and other physicians know much
about protozoa. Therefore the errors common among
protozoologists in evaluating disease when associated

INTRODUCTION xvii

with the presence of protozoa and among physicians
in estimating the significance of the finding of pro-
tozoa in a sick person.

Particularly is the practicing physician prone to
err when he is searching for the cause of a confusing
disease and finds such an optically prominent thing
as a protozoon in the stool. It appears as if it should
be doing something harmful. The physician does
not ordinarily become so concerned about the myri-
ads of bacteria also present. They are not so promi-
nent to the eye. This prominence of the relatively
large protozoa is undoubtedly responsible for the
difficulty which many have in passing them by. One
may well wonder if more actual harm than good has
not come from routine stool examination, as used
up to the present time.

CHAPTER I

The Life of Protozoa

History and General Considerations. Anatomy and
Physiology. Characteristics of the Cysts. Life History.
Specificity of Parasite for Host. Resistance and Immunity
of Hosts. Encystment. Reproduction.

HISTORY AND GENERAL CONSIDERATIONS
OF PROTOZOA

The discovery that our universe is populated by
living organisms of insufficient size to be seen by the
unaided human eye belongs to Antoni van Leeuwen-
hoek (1632-1723), the great Dutch microscopist. He
it was in 1675 who first saw, with the aid of a micro-
scope of crude proportions as compared to the appara-
tus of the present day, minute animals which are
called Protozoa. He studied them as free living
forms, as parasites of lower animals, and as parasites
of man, finding himself the host of one, which Dobell
identifies as Giardia (Lamblia) i7itestinalis.

He thus became the discoverer of a world of life,
unknown before that time and now unknown to the
vast majority of people, the population of which far
exceeds in number the visible animal population of
the world.

1

2 PROTOZOAN PARASITISM

Scattered far and wide over the earth, they live
wherever they find sufficient moisture even for a short
period of activity, lying dormant when their medium
is no longer liquid. In their dormant phase, which
we call cysts, they protect themselves by a capsule
formed from their own secretion, in which they may
survive drought conditions for variable lengths of
time.

Warm wet regions are thus most favorable to them
and the waters of such climates teem with their num-
bers. The sands of the desert, the dust of the earth
and air, the ice of frozen regions, however, harbor
them, waiting for favorable conditions for continued
activity.

It is probably not to be supposed that the forms
which we see today are the same as their ancestors,
nor is it to be thought that they are the forbears of
higher animals. Such is sometimes the conception
of the ignorant concerning the meaning of evolu-
tion.

Undoubtedly the species which we know today as
free living forms and as parasites upon higher animals
and man have evolved from common ancestors.
Adaptation to changed or new environment has pro-
duced division into species, races and strains, specifi-
cally suited to the environment in which they live.
Thus the different species of one kind of protozoa
living in freedom or as parasites in man and other
animal hosts are close akin, at times difficult to dis-
tinguish from each other, and yet usually distinct

OF THE ALIMENTARY TRACT 3

and not interchangeable from one kind of animal
host to another.

The bodies of the active form of protozoa are naked
and their locomotor apparatuses are but primitive.
They are therefore largely dependent upon a liquid
medium for their activities of movement and search
for food and for protection from evaporation of the
water of their own bodies. Some are dependent upon
food in solution, also. Consequently the necessity of
a fluid environment for them. Those which are not
subject to periodic drying of their habitat and which
do not need protection in passing from one host to
another exist mainly in the naked active form and
do not encyst.

Various temperatures of their fluid mediums are
suitable to the various species. Activity of free
living species goes on under considerable natural tem-
perature variation. Activity in those parasitic in
cold blooded animals has an optimum temperature
corresponding to that of the host. In the protozoa
of warm blooded animals warmth of the range of the
host is the optimum state for activity and they usually
cease motion and soon die upon cooling, even for a few
degrees.

Naturally the naked forms are very susceptible to
heat and the cysts are also killed at a definite and not
high degree, as is known for some parasitic species.
While cold readily kills the active protozoa of warm
blooded.animals, the free living and those of the cold
blooded may survive and may even be active short of

4 PROTOZOAN PARASITISM

freezing and the cysts of some may survive even that
temperature.

Within the bodies of these minute beings occur
all of the complex processes of life. They live and
move and have a being. They move about purpose-
fully, they ingest food, they inhale, they digest, they
metabolize, they reproduce their kind. Under un-
favorable conditions they sicken and die, under fa-
vorable environment their lives and their bodies
are continued in their offspring ; they are essentially
immortal beings.

The construction and organization of their bodies
is of the simplest, and at the same time complex.
The secrets of life are concentrated here in a form
which may be seen in toto, the different scenes en-
acted in periods of time so short as to be subject to
continuous observation. Consequently many have
thought and tried to determine what has remained
hidden from the mind of man by study of the lives
of protozoa.

ANATOMY AND PHYSIOLOGY

A protozoon is a minute animal, the organs and
systems of which, with their specialized materials,
are not separated into anatomical units called cells.
The whole body bears physical resemblance to a
single cell of the higher animals, in that in a general
pattern it is composed of cytoplasm and nucleus, and
in that sense is unicellular. Physiologically the pro-

OF THE ALIMENTARY TRACT 5

tozoon is non-cellular. To designate a protozoon as
a single cell or a unicellular animal seems inade-
quate or insufficient to some who are most familiar
with them, but there seems to be no way to avoid
the visual fact of a single celled body as long as the
cell is the generally recognized unit of life and until
we are in possession of deeper knowledge concerning
the fundamental factors or units of life beyond the
physical cell. Just as the fundamental unit of mat-
ter has changed in our conception with growing
knowledge, so will our ideas of the unit of living mat-
ter change and perhaps there will come a time when
cellular biology will be as inadequate as the molecular
idea may be in physics.

Until then perhaps we should adhere to the con-
ventional and speak of Protozoa as unicellular ani-
mals, as differentiated from Metazoa, or higher
animals, in which the same or comparable vital organs
or systems are organized as separate recognizable
physical cells. It is common to think of the various
systems of the protozoa as of low order, primitive.
The size of their bodies, the accessibility of all parts
to food, water and oxygen absorption, the ease with
which waste materials may be cast out, the joining
of the principals of somatic and germ life in one
nucleus; all do away with the necessity for highly
complex alimentary, digestive, circulatory, respira-
tory, excretory, reproductive, and nervous systems.
Their organization is entirely adequate for their
lives, in fact the advantage which they have over

6 PROTOZOAN PARASITISM

larger and necessarily more complex animals is com-
monly manifest.

The bodies, then, of protozoa are organized into
specialized systems corresponding to those which we
know in higher animals, constructed of specialized
materials but not of separate and specialized cells.

The outer part of the body is called the ectoplasm
(outer substance). Here the protoplasm is of more
uniform consistency, for a variable width in different
forms. There is no separate surface covering or at
least only a condensation which keeps the body in-
tact.

From the surface are projected the organelles of
locomotion and food gathering. Some of them pos-
sess for these purposes the ability to produce pro-
trusions from their bodies, called pseudopodia (false
foot). These are not permanent features but are
projected on proper stimulus toward food materials
or in the direction which the body is to travel. When
a pseudopodium is used for gathering food it is ex-
tended to and wrapped around the article. This is
taken directly into the protoplasm through a solution
in the continuity of the rim, which immediately is
healed.

When locomotion takes place by pseudopodia the
projection of ectoplasm takes place in the desired
direction and the inner substance, endoplasm, flows
into it, much as a thick-walled flexible bladder of fluid
may pass through a small aperture.

Pseudopodia are thus feet for moving and hands

OF THE ALIMENTARY TRACT 7

for feeding. Their protrusion seems to be by ex-
ternal stimulus on the part of desirable food sub-
stances.

Thus there is a primitive sense system, corres-
ponding to the sight, smell, taste, and touch organs
of higher animals.

A protozoon possessing pseudopodia is known as
an amoeba (change).

Some protozoa have, instead of pseudopodia,
flagella (whip). A flagellum is a lash-like filament
extended as a more or less permanent organelle from
the surface of the body, the number and position of
these processes varying with the species of flagellates,
so named from this feature.

A flagellum is constructed of a filamentous core
attached centrally to certain little bodies called
blepharoplasts which are intimately connected with
the nuclear apparatus, the central control organ, this
core projected through the surface membrane or
ectoplasm and carrying the covering with it. Fla-
gella are moved in rythmic lash-like manner and
serve as organs of locomotion and food gathering.
They evidently have tactile sense. In food gathering
they whip or brush particles into contact with the
surface of the body, w^here they are then ingested.
They are used as propellers in free swimming loco-
motion and protozoa possessing only this means of
propulsion usually move about in a jerky manner.
Smoother movement of some flagellates results from
other swimming appendages or from a posteriorly

8 PROTOZOAN PARASITISM

projected flagellum of spiral or screw-like move-
ment.

Some flagellates have very pliable bodies, so that
they may twist and turn and so force their way among
solid materials in their liquid mediums by paths
smaller than their bodies. Such pliable bodies give
a darting action to the organisms. Others have very
rigid bodies of unchanging contour. Some are twisted
so that forward movement occurs in spirals.

Another specialized organelle of locomotion is the
undulating membrane. This is a fin-like affair ex-
tending for various distances over the surface of the
body. It has a stiffening rib, similar to the core of a
flagellum and having a similar origin, which raises
up a covering of ectoplasm to form a ruffle. The
undulating or snake-like motion of this stiffening rib
and ruffle-like covering furnishes a means of rapid
motion. In a sluggish individual the slow undulation
of this ruffle has been confused by some with pseudo-
pod projection and has led to the report of an undu-
lating amoeba (Avioeha undulans, Castellani).

Still another apparatus for locomotion and for
feeding is a surface covering of cilia (eyelid). Cilia
are comparatively short hair-like bristles which cover
the bodies of the ciliates. They move in rythmic
order like standing grain in a wind or the feet of a
thousand-leg, creating currents to propel the organ-
ism or to sweep food materials into reach of the in-
gesting surface.

The different external appendages of protozoa,

OF THE ALIMENTARY TRACT 9

then, serve the purpose of locomotion or of food
gathering or both.

Protozoa are voracious feeders. They live to eat
to multiply.

Some have no apparent mouthpiece but may en-
gulf solid particles through a seemingly unbroken
ectoplasm. Pseudopodia or ectoplasmic processes
from any part of the body may wrap themselves
around a food body and enclose it much as flowing
water will surround a stone.

Some absorb foods in solution.

Some hav6 stomata (mouth) which to most ob-
servers may appear more imaginary than real. They
may be merely specialized surfaces through which
food particles are taken when they are brushed against
them by food gathering organelles. These mouth-
pieces are usually depressed at least.

Others have more definite stomata w^hich may be
readily seen and recognized as pores or orifices. Food
materials are thrown into them by flagella or cilia.

Foods of various kinds, bacteria, yeasts, molds,
other protozoa, starch granules, crystals, materials
from the tissues of the host, liquids, etc., are thus
ingested through the ectoplasm and are swallowed,
so to speak, into the interior of the body, the endo-
plasm (inner substance).

Here they are brought into contact with the se-
cretions, the digestive juices. Usually there is formed
about on-e or more of these swallowed substances a
cavity into which is poured the digestive fluid.

10 PROTOZOAN PARASITISM

These cavities are commonly called vacuoles. They
are essentially stomachs.

The gastro-intestinal system of the protozoa is
therefore a remarkably adjustable one.

In these vacuoles the usable nutriment is prepared
for absorption and metabolism. It is used or stored,
as the need may be, the storing of reserve materials
being apparently mainly a preparation for hiberna-
tion in the encysted phase, where sometimes multi-
plication takes place.

The waste from digestion, and probably from the
completed metabolism, is expelled to the exterior.
Excretion thus takes place, commonly by rupture
of a vacuole containing waste material through some
part of the ectoplasm, sometimes through a special
or pore-like excretory aperture.

The smallness of the bodies of these animals and
the accessibility of the protoplasm to the diffusion
of gases enables them to do without special respira-
tory tracts and systems, necessary to larger animals.
There are no recognizable structures directly con-
cerned with respiration. Parasitic protozoa, living
in the dark of the bodies of their hosts, possess no
chromotophores (color bearer) by which oxygen may
be separated from carbon dioxide of their mediums,
such as some free living forms exposed to light have.

Internal metabolism by protozoa is carried on by
more or less constant movement of the cytoplasm in
currents.

The structure of the inner substance (endoplasm)

OF THE ALIMENTARY TRACT 11

is generally alveolated, that is there exists a reticu-
lated network frame structure, corresponding to the
connective and framework tissues of higher animals.
This network holds the fluid substances in order and
allows the development of currents of interchange of
substances of secretion, nutrition, and excretion, in
other words a circulation adequate for the needs of the
animal.

The center of life and its activities in protozoa is
the nucleus. This body is located in the endoplasm,
and corresponds in a general way to the nucleus of
the cells of higher animals in its construction, essen-
tial character, and manner of participation in division
of the organism. It has a limiting membrane enclos-
ing a network of (linin) fibrils, within the meshes of
which lies the fluid of the nucleus, and arranged on
this network or clinging to the rim is the chromatin,
the particularly essential nuclear substance. This
chromatin is variously distributed in different forms
and its arrangement is so typical in some that it is
used as one basis of differentiating and identifying
them. The common nuclear appearance of those
with which w^e are here concerned is that with a
definite rim, rounded in outline, with granules of
chromatin of varying sizes clinging to the inner
surface of the rim and also accumulated in or near
the center in a mass called the karyosome. The linin
network is more or less distinct and on its threads may
appear chromatin granules.

The nucleus is necessary to the continued exist-

12 PROTOZOAN PARASITISM

ence of a protozoon, it is the directing factor of its
activities, it carries the hereditary characteristics of
the species, and it naturally plays the essential role
in division and the production of offspring. It is
the directing force of somatic life and, at the same
time, the germ of the offspring.

CHARACTERISTICS OF THE CYSTS

Each encysting species has its own peculiar cyst,
the importance of which in identification of the para-
site is not as widely recognized and attended to as
it should be. Particularly is this the case in the two
intestinal amoebae of man between which it is of so
much importance in medicine to distinguish.

The shape and size of protozoan cysts are char-
acteristic of the species, the contour being more nearly
rounded than in the vegetative phase and the size
usually reduced. The cyst wall or shell is of con-
siderable thickness in some and of less definiteness
in others. The body of the organism is condensed
and usually motionless after the stage is fully de-
veloped. The cytoplasmic division into ectoplasm
and endoplasm is not definite. The various organ-
elles of the vegetative phase are indistinct or not
seen. Undigested food bodies are absent but some
contain stored materials, such as glycogen. Some
contain ''chromidial" bodies, in the shape of slivers,
bars, or blobs, which take the nuclear stain. The
nuclei of the cysts are characteristic of the species, in

OF THE ALIMENTARY TRACT 13

form and number. In those which multiply within
the cysts, the nucleus divides, by mitosis, and each
daughter nucleus continues the division until the
full number for the species is produced.

When the process of intracystic reproduction is in-
complete the nuclei are usually large and hyperchro-
matic, when complete they are characteristic in size,
shape and appearance.

Cysts in their natural state appear as glassy or
hyaline bodies.

LIFE HISTORY

Protozoa either spend their lives as free-living
animals in suitable environment, usually in water,
or they live in connection with other animals. Ac-
cording to the nature of this association they may be
commensals, which are dependent upon their asso-
ciation with their hosts but cause them no damage.
Others live in symbiosis, where both of the parties
to the association derive some benefit from it. Still
others are parasitic upon their hosts, that is they
cause some injury by utilization of materials needed
by the host or by producing substances harmful to
the host tissues. In this strict sense the protozoa
here under consideration are either commensals or
parasites and the debate has been as to which class
the several kinds belong.

It has come to be the popular conception that "a
living organism which, for the purpose of procuring
food, takes up its abode temporarily or permanently,

14 PROTOZOAN PARASITISM

on or within another living organism" is a parasite.
There is something to be gained by adhering to this
conception and, following Craig's example, I have
taken this definition from Fantham, Stephens and
Theobald (1916). In this sense all the organisms
here considered are parasites of man and are so
classed. Some of these parasites are pathogenic and
some are apparently not.

As has been frequently called to attention the
natural host of a parasite is one which has usually
become adapted to it and which is ordinarily done
comparatively little harm by it. Otherwise the para-
site would have but little chance of survival, since
it is dependent upon the opportunity of transmission
to other hosts before its own death occurs with the
death of its carrier. Consequently when severe dam-
age is done the host by the parasite it is to be suspected
that this is an unnatural association.

SPECIFICITY OF PARASITE FOR HOST

Further, it has come to general recognition that
there is more or less rigid relationship between para-
site and host, even to the point that most of them are
able to survive only in their own particular hosts and
in only one particular place in that host. These are
very important points in considering the relation of
protozoan parasitism in general to human medicine.
Were this not the case, were the very great number of
protozoa parasitic in other animals transmissible to

OF THE ALIMENTARY TRACT 15

man, and were those of the several divisions of man's
alimentary tract readily disseminated to other parts,
the case would be tremendously complicated and
much more important than it is. The popular con-
ception that we receive our protozoan parasites from
the animals with which we have surrounded our-
selves is generally not true. Consequently, the
matter of prevention comes to mean mainly the pro-
tection of man from contamination with the excreta
of his own kind.

When, theoretically at least, we find a protozoon
producing a definite disease as a constant or common
result of its parasitism, it may be suspected that it
is not a natural parasite of this host and search for
its natural host should be made, since control of it
would probably involve control in the natural host.

In naturally occurring infections there is ordi-
narily a state of balance between host and parasite.
Occasionally this balance does not occur or is broken
down.

RESISTANCE AND IMMUNITY OF HOSTS

Natural immunity, therefore, exists in most ani-
mals against the parasites of other species. This
may be broken down at times. There is also natural
immunity of some individuals to parasites of their
own species, acquired immunity. Definite knowl-
edge of the development of resistance to the parasites
under question here, following their invasion, does not
exist. It is indicated by Craig (1926), who reports

16 PROTOZOAN PARASITISM

obtaining complement fixation between antigen made
of cultures of Endamoeba histolytica and the blood of
hosts of this parasite, by Wagener (1924), who found
positive precipitation of extracts of scraped mucosa of
amoebic colitis by blood serum of cats experimentally
infected over a week with Endamoeba histolytica and
negative controls in other cats, and by Wagener and
Thomson (1924), w^ho found that kittens previously
infected with Endamoeba histolytica from chronic
human amoebiasis w^ere more difficult to infect with
amoebae of more virulent strains than were normal
animals of the same age and size. It is, perhaps, in-
dicated by the experimental production by the author
of encystment of Trichomonas caviae in the blood
serum of its own individual host.

This occurred during the course of culture of
Trichomonas caviae at 37.5°C. incubation in medium
composed of one part of the animal's own fresh
blood serum in nine parts of 0.9% sodium chloride
solution, but did not occur in similar medium of
other serum.

It is common knowledge that the number of para-
sitic protozoa to be found varies widely from time
to time and that they may die out completely. This,
however, may be due to alteration of the state or
content of the medium in which they live and not to
the development of ^'antibodies" by the host. The
work of Hegner (1923), in attempting to control the
number of flagellates in the intestine of the rat by
a protein diet, indicates that the diet may be an im-

OF THE ALIMENTARY TRACT 17

portant factor in determining the growth of such
parasites after their introduction.

In this connection an observation of the writer in
the production of experimental intestinal amoebia-
sis in the rat is, perhaps, worthy of note. Rats fed
on stale w^hite baker's bread exclusively w^ere more
readily infected than those on a more varied diet and
the colitis found was more extensive and active.

The relation of the diet to the development of para-
sitism of these organisms and, further, to the effects
produced upon the host by the parasite is a promis-
ing problem for investigation.

ENCYSTMENT

Most of the protozoa of the alimentary tract, as
is the case in general with protozoa, are able to form
about their bodies a resistant capsule, when condi-
tions are not favorable for continued vegetative
existence in their environment. In some this en-
cystment is consonant with preparation for multipli-
cation, so that w^hen again ready for activity the
animal emerges from the cyst in the form of its
offspring.

Immediately prior to encystment there is a slowing
up of the movement of the body and usually con-
traction to smaller size, extrusion of food materials
from the body, and, in some, a slow revolvement of
the body while the cyst is forming. This contracted
stage is the ''precystic" form.

18 PROTOZOAN PARASITISM

Just what is responsible for the phenomenon of
encystment is not known. In certain free living
forms it occurs when the liquid medium of the or-
ganism is drying. In certain forms which inhabit
the intestine it occurs in the lower parts, as the bowel
content becomes more solid. In certain cultures of
these organisms it has appeared to take place, in no
regular fashion, as the medium became inspissated
and concentrated. It has been recited above that
the writer had the occasion to observe encystment of
numbers of Trichovionas caviae in a medium of the
serum from its own guinea pig host, whereas the
change did not occur in similar medium from other
guinea pigs.

Some of the cysts produced by the protozoa are
purely for protective purposes, and only the one
organism emerges from the cyst when conditions
again are favorable. In others, while the cyst is
protective, it is at the same time reproductive, and
the organism may divide into two or more offspring,
as the case may be, which may later emerge from the
cyst.

In some protozoa encystment is a definite and regu-
lar part of the life cycle, essential to its continued
life.

With most parasitic protozoa it is essential to the
continuation of the species, in that it is the particular
form in which they are able to survive exposure to
the external world and the vicissitudes of transfer-
ence to a new host.

OF THE ALIMENTARY TRACT 19

In general the process of encystment has been
evolved by the individual species as best suited to
their needs, some for reproduction, some for protec-
tion in unfavorable environment and reproduction,
some purely for protection, while some are not de-
pendent upon such a change for either protective
or reproduction purposes and do not encyst.

Neither is it definitely known what leads the en-
closed organism to escape from its cyst when it
reaches a favorable environment for its further ac-
tivity. It has long been assumed that the digestive
juices of the alimentary tract cause dissolution of the
cyst and allow the imprisoned parasite to escape.
It is possible, however, for these same organisms to
escape and continue their activities without such
digestive action on the exterior, as witness the cul-
tures which may now be grown from cysts of some of
these organisms. It seems, therefore, that their es-
cape is due to their own ''digestive" influences upon
the shell which they have formed, some forms leaving
a pore of more easily dissolved material through which
they may escape.

In the writer's laboratory notes of 1922, before
the recent reports of cultivation of various amoebae
of man, occurs the record of attempts to grow man's
intestinal amoebae in a serum salt solution mixture
similar to some which have since been reported as
suitable for such culture work. It was observed that
after 24 hours incubation at 37 °C. cysts were empty.
Free amoebae were found but transplantation was

20 PROTOZOAN PARASITISM

unsuccessful. In the light of the report of Yorke and
Adams (1926), and that of Allen (1926), it is be-
lieved that observation of excystation of these am-
oebae was truly observed and that primary cultivation
was successful. The illustration of the ruptured
cysts by Yorke and Adams conforms essentially to
those seen and drawn at that time. These writers
believe, from their investigations, that excystation
of Endamoeba histolytica requires only moisture and
suitable temperature (37°C.), while Allen reports
that in order for Councihnania lafleuri to excyst in
culture the cysts must reach the proper phase and
the medium must have necessary chemical and physi-
cal conditions, it occurring in their experiments in
Ringer's solution with 0.01% dextrine but not in
other media.

At any rate escape from the cysts takes place under
conditions suitable for the free activity of the organ-
ism and it emerges as one or more, in the different
forms.

REPRODUCTION

Although reproduction of protozoa may be sexu-
ally or asexually, the latter is the usual means in the
species parasitic in the alimentary tract of man.
Division occurs by binary fission as the means of
multiplication in the vegetative phase, two identical
bodies, but commonly smaller, resulting.

The nucleus first divides bv mitosis and then the

OF THE ALIMENTARY TRACT 21

cytoplasm is separated evenly for the two individ-
uals.

In the case of multiplication within cysts, which
occurs in some of these species, the mitotic division
of nucleus and nuclei proceeds to the production of
the number characteristically formed, although some-
times multiples of the usual number are seen, before
division of cytoplasm takes place. In some the com-
pletion of the process does not occur until excysta-
tion, when the smaller offspring, corresponding to
the number of nuclei, are liberated.

CHAPTER II

Dissemination and the Prevention
OF Infection

The protozoa of man's alimentary tract are com-
monly transmitted from the human carrier to a new
host by contamination of materials taken into the
mouth by secretions or excretions of the infected in-
dividual, in fact the commonness of these organisms
in man is a concrete illustration of the real uncleanli-
ness with which the human is still in contact, in spite
of vaunted sanitary procedures. This has been
particularly stressed by Boeck and Stiles (1923), and
by Dobell and O'Connor (1921). The incidence of
intestinal protozoa is a direct index of the swallowing
of fecal matter.

Those which inhabit the mouth are probably trans-
mitted by kissing and by the placing of things in the
mouth which are contaminated with saliva from the
infected person. Ready passage of the mouth pro-
tozoa from one person to another is indicated by their
failure to encyst.

Of those of the intestine, the encysting species find
this resistant phase necessary to survival of an in-
terval between passage, with excreta, from their

22

OF THE ALIMENTARY TRACT 23

hosts and the opportunity to be swallowed by an-
other person. The failure of an intestinal species
to encyst indicates that it is able to survive this period
of external exposure in the vegetative form, and, also,
to pass down the alimentary tract to its natural
habitat unharmed by secretions above. This pas-
sage of the stomach by Trichomonas in active form
we know takes place.

The non-encysting must necessarily be transferred
in liquid or moist medium, consequently we may sus-
pect the commonly ingested liquids or moist foods
which are not heated in preparation. The observa-
tion (Lynch, 1926) that Trichomo7ias is a common
parasite of warm regions and rural populations and
uncommon in colder climates and urban and institu-
tional inhabitants is in support of this belief.

It seems readily appreciable that the prevention
of contamination of water and other liquids and fresh
moist foods, or sufficient refrigeration, or, on the con-
trary, the heating of them to a degree sufficient to
kill vegetative forms w^ould bring about the elimina-
tion of unencysting intestinal protozoa as human
parasites. Modern measures of sanitation, sewerage
disposal, control of drinking water and milk, seem to
be sufficient for the purpose and to be responsible for
the low incidence of Trichomonas in people of such
hygienic environment.

The species which are transmitted in the encysted
state offer a different problem. Certain institutional
surveys, notably by Thomas and Baumgartner

24 PROTOZOAN PARASITISM

(1925), indicate that such hygienic measures are
without avail in preventing the spread of these para-
sites and that close personal contact leads to a steady
increase in incidence. Hand to mouth transmission
and the food handler carrier are undoubtedly promi-
nent means of spread of these parasites in places
where there is proper disposal of human excreta and
protection of water and food from fecal contamina-
tion. That being the case, protection against the
carrier must be the means of prevention of such trans-
mission.

In places where there is exposure and improper dis-
posal of fecal matter, the transfer of cysts by flies
and the contamination of food and drink by them are
probably means of spreading these parasites, and
prevention of such dissemination must mean the con-
trol of such conditions.

Flies may carry live protozoan cysts in their in-
testinal tracts, after ingesting them from human
excreta, for probably several days, during which time
they may contaminate food with them in their own
excreta. They may also carry cysts upon their legs,
although parasitic protozoa do not survive drying for
any considerable period, even in cysts.

As for those which may be obtained from other
animals there is one of importance which is appar-
ently so spread, and there is another, the most im-
portant intestinal protozoon of man, which may pos-
sibly be spread in such a manner.

The former is Balantidiuni coli, a natural para-

OF THE ALIAIENTARY TRACT 25

site of swine, which is occasionally transmitted to
man by swallowing materials contaminated with
fecal matter from this animal. The means of pre-
vention of such infection by those who may be
exposed to it in handling hogs is evident.

The latter is Endamoeha histolytica, which has
been shown by the writer and others to be capable
of transmission to and parasitism in the common wild
rat. If such should be the case in nature this is
potentially a source of spread of the parasite, and the
control of the rat, prevention of contamination of
food by the excreta of it, and protection of human
excreta from this animal, would be necessary to pre-
vent such a manner of spread. It seems possible at
the present wTiting that in regions where human
excreta are exposed to rats which also have access
to food of man, this natural means of transmission
of this important parasite may occur. It is of suf-
ficient importance to demand attention until proven
or disproven, at any rate. More recently Kessel
(1928) has found an amoeba, identified as Endam-
oeba histolytica, in naturally infected pigs in Peking,
China, and has, also, brought about experimental
infection of this animal by Endavioeha histolytica for
a period of about six weeks. The pig is thus, also,
accused of serving as a natural carrier of this amoeba
and, if so, needs be guarded against in places where
such an opportunity may be given it.

The transmission of these parasites, then, depends
upon their natural habits of life, in relation to those

26 PROTOZOAN PARASITISM

of man, and the prevention of it involves breaking
the chain of sequence at some convenient or avail-
able point.

Thorough application of commonly recognized hy-
gienic and sanitary procedures, personal and public,
would probably suffice to control most if not all of
these human infestations. Such a thorough applica-
tion as to bring about their eradication is not to be
anticipated, however, at the present or in the immedi-
ate future, particularly as regards personal hygiene
and the control of the hand to mouth transmission,
which is believed to be probably the most important
means of spread of these parasites in modern com-
munity life.

It should be emphasized that the carrier furnishes
the real problem in this division of preventive medi-
cine. He it is who furnishes the transferable stage
of the organism, not the person acutely ill of an in-
fection which is being excreted in a non- transmissible
stage of the organism. A patient with acute am-
oebic dysentery is of no danger to anyone else, the
amoebae he passes are harmless. It is in the absence
of diarrhoea that he becomes of danger to his fellow.

When it is called to mind that apparently about
10% of the population of any country harbors a
pathogenic amoeba in transferable form and that
probably from 30% to 50% of all people carry
some intestinal protozoon, to say nothing of the or-
ganisms of the mouth, it is to realize how hopeless
it is to contemplate any considerable reduction of

OF THE ALIMENTARY TRACT 27

this class of human parasites in any given period
of time.

Fortunately it seems unnecessary to even enter
into such a consideration and it appears that the oc-
casional cry of an alarmist is unwarranted. There is
no indication of the post-war spread of intestinal
amoebiasis which some professed to fear.

Particular conditions which must be considered
and special measures which may be instituted in the
prevention of the spread of these protozoa wdll be
taken up under the consideration of the separate
species.

TRANSMISSION OF ALIMENTARY TRACT PROTOZOA

1. By autoinfection. Transfer from one habitat to
another in the same individual, in trophozoite
stage.

A. Trichomonas vaginalis — to the mouth (?).

B. Trichoiyionas hominis — to the vagina (?).

C. Trichomo7ias buccalis — to the vagina (?).

2. By direct personal contact, in trophozoite stage.

A. Endamoeha gingivalis.

B. Trichomonas buccalis.

C. Trichomonas vaginalis (?).

3. By indirect means, in trophozoite stage.

A. Trichomonas hominis.
(Contamination of food and drink by fecal
matter).

B. Chilomastix mesnili ( ?) .
(Contamination of food and drink by fecal
matter).

C Endamoeha gingivalis.
(Salivary contamination.)

28 PROTOZOAN PARASITISM

D. Tricho7no7ias vaginalis.
(Douche contamination ?).

E. Trichomonas buccalis.
(Salivary contamination.)

4. By indirect means, in encysted stage. Direct
fecal contamination of food and drink and eating
utensils or by means of flies.

A. Endamoeha histolytica.

B. Endamoeha coli.

C. Endolimax nana.

D. lodamoeba biltschlii.

E. Chilomastix mesfiili.

F. Giardia intestinalis.

G. Eiyibadomonas intestinalis.

H. Tricercomonas intestinalis. ♦

I. Enteromonas hominis.

J. Balantidium coli.

K. Isospora belli.

L. Eimeria gubleri ( ?) .

5. Indirectly from man through the medium of an-
other animal host, in encysted stage (?).

A. Endamoeha histolytica. (Monkey. Rat.
Domestic pig.)

B. Balantidium coli. (Domestic pig.)

6. From other animals, themselves natural hosts of
the parasite, in encysted stage. Direct fecal con-
tamination of food and drink or of hands, or by
mean of flies.

A. Balantidium coli. (Domestic pig.)

B. Endamoeba histolytica. (Rat?).

7. From other animals, themselves natural hosts of
the parasite, in trophozoite stage. Salivary con-
tamination of hands or objects or substances taken
into the mouth.

A. Endamoeba gingivalis (?). (Dog. Monkey.)

B. Trichomonas buccalis (?). (Dog.)

OF THE ALIMENTARY TRACT

29

CLASSIFICATION OF THE PROTOZOA OF
THE ALIMENTARY TRACT OF MAN

PHYLUM

CLASS

ORDER

GENUS

SPECIES

Protozoa

■1
1

<

Endamoeba

histolytica

coU

gingivalis

Endolimax

nana

lodamoeba

butschUi

Dientamoeba

fragiUs

o

X,

a
1

Monadida

Trichomonas

hominis

buccalis

Chilomastix

mesnili

Giardia

intestinaUs

Embadomonas

intestinalis

Enteromonas

hominis

Tricercomonas

intestinalis

1

2

1
6

Eimeria

gubleri

Isospora

belli

hominis

Ciliata

c3

1

Balantidium

coli

minutum

Nyctotherus

baba

CHAPTER III

The Amoebae

Classification. General Considerations and Morphol-
ogy. Methods of Examination for Amoebae.

class: rhizopoda.
order: amoebida.
genus: endamoeba.

species: E. histolytica.
E. coli.
E. gingivalis.
genus: endolimax.

species: E.nana.
genus: iodamoeba.

species: /. biitschlii.
genus: dientamoeba.

species: D.fragilis.

THE AMOEBAE (AMOEBIDAE).

Of the order of Protozoa known as the Amoebidae,
there are four well recognized genera parasitic in the
alimentary tract of man, Endamoeba, Endolimax,
Iodamoeba, Dientamoeba, and there are others not
yet, I believe, sufficiently accepted, such as Council-
mania and Caudamoeba. The amoebae are those

30

OF THE ALIMENTARY TRACT 31

organisms which typically move and feed by the
means of pseudopodia, that is by currents in their
cytoplasm which may stream to a local part of the
surface producing a finger-like projection, or may
flow as a whole in one direction, leading to progres-
sive locomotion.

The cytoplasm of the body shows division into a
peripheral ectoplasm of apparently uniform consis-
tency, and an inner endoplasm of more or less alveo-
lated, vacuolated, or granular appearance. The ecto-
plasm is particularly specialized for the formation of
pseudopodia, in other words conforms to and fulfills
the purpose of the peripheral apparatus of all animals,
i.e. locomotion, feeding, excretion, and maintaining
contact with the external environment. In the endo-
plasm occur the nucleus, the digestive cavities, etc.,
in other w^ords the interior apparatus of the animal
body, the "vital organs" and systems.

This division into ectoplasm and endoplasm varies
among the genera, between species, and with in-
dividuals.

The nucleus is usually single and varies among the
species to give characteristics commonly depended
upon for differentiation.

All but one of the species found in man are known
to undergo encystment. The amoeba of the mouth,
Endainoeha giyigivalis, apparently does not encyst.
It has no need of a phase for protection against ex-
ternal exposure since it naturally would be trans-
mitted directly from person to person by contact.

32 PROTOZOAN PARASITISM

e.g. in kissing, or through the intermediation of the
common use by mouth of the same materials, such as
in drinking, etc. On the other hand the amoebae
which inhabit the intestine must live through the
vicissitudes of passing out of the host, of external ex-
posure for varying periods of time and in contact
with various substances, and then through the di-
gestive juices of the upper alimentary tract, par-
ticularly the stomach, before reaching their natural
habitat again. Consequently encystment has been
necessary for their survival. In the important ones,
if not all of these amoebae, there is multiplication of
nuclei to a definite number during encystment, pre-
paratory to the liberation of its offspring.

Reproduction in the vegetative phase is by binary
fission, with the production ordinarily of two indi-
viduals, this being the method of multiplication dur-
ing their natural life in the intestine. It is doubted
that the cysts hatch naturally until a new host is
invaded since the cysts are formed as the organisms
pass down the lower intestine to be excreted.

METHODS OF EXAMINATION FOR AMOEBAE

For study of the fresh active forms a portion of
the fluid content of the natural habitat of the organ-
isms is necessary. Depending on the consistency of
this medium it may be necessary to mix it with physi-
ological saline solution. The material should be
placed on a microscopic slide in thin enough state to

OF THE ALIMENTARY TRACT 33

be clear to microscopic vision under a cover glass.
The temperature of the medium should be near that
of the body. In ordinary summer weather they will
usually live and remain active for several hours. In
the winter the material may be kept in the ordinary
bacteriological incubator, or otherwise at about body
temperature, in which case the amoebae will usually
be active enough during the time of the examination,
unless the room is cold. Tough mucus and thick or
heavy particles of solid matter should be avoided.
Ordinarily it is sufficient to take a bit of the material
to be examined on the end of a match stick or wooden
applicator stick and mix it uniformly with a drop of
saline solution on the slide, after warming it to about
body temperature. In case of a thin watery stool
or of a mucinous stool it may not be necessary to use
saline solution.

The active amoebae will be found after a short
time to emerge from the heavier particles of the
preparation and to cross the streams of liquid. Af-
ter they have been located by the use of the ordinary
low dry lens, they may be studied with the high dry
objective, the oil-immersion being of little service
beyond this. Dark field examination is striking but
reveals nothing in addition. The points which may
be determined from this examination are the size,
the visibility of the nucleus, the character of the
pseudopodia, the nature and activity of locomotion,
the contrast of ectoplasm and endoplasm, the kind of
food particles in the vacuoles of the endoplasm.

34 PROTOZOAN PARASITISM

It is well to have such fresh liquid material for
the determination of the presence of amoebae. It
is not by any means always possible to identify them
under these conditions. Frequent errors are made
in diagnosis by depending upon this preliminary part
of the examination. When amoebae are found it may
be possible to form a good idea as to their identity,
frequently it is impossible, always it is advisable to
simply recognize the presence of an amoeba and, if
no cysts are to be found, to wait until they may be
before making a positive identification. This does
not mean that it is necessary to wait for the cysts of
Eridmnoeba histolytica before a diagnosis of intes-
tinal amoebiasis is made. The character of the am-
oeba, its common red blood corpuscle inclusion, and
the clinical nature of the case, particularly the nature
of the stool, practically always allows a diagnosis of
amoebic dysentery at once and with positiveness.

In chronic intestinal amoebiasis without dysentery
discovery of the cysts is practical and should be done
for a positive diagnosis.

For better study of the nucleus and composition
of the body, food particles, etc., stained specimens
are necessary. The best stained preparations are to
be secured by the iron-haematoxylon methods about
as follows:

1. Make thin spreads on slides (cover glass prep-
arations are less easily handled) and before they can
dry fix them in warm "Schaudinn's solution" (2 parts
saturated solution of bichloride of mercury to 1 part

OF THE ALIMENTARY TRACT 35

of absolute alcohol, to each 100 cc. of which mix-
ture is added 5 cc. of glacial acetic acid) for 10-30
minutes.

2. Rinse in 50^/c alcohol.

3. Remove the remainder of the corrosive sub-
limate by placing in a weak alcoholic solution of
iodine for about 15 minutes.

4. Pass through alcohols, 70%, 80%, and 90%,
and wash in distilled water.

5. Mordant in 4% iron-ammonia-alum over-
night.

6. Rinse in distilled water and from weak to strong
grades of alcohol.

7. Stain in 1% alcoholic haematoxylon until the
films are well blackened.

8. Rinse the excess of stain in water and differ-
entiate in 2% iron-ammonia-alum. This is the step
requiring most skill and attention. It can be mas-
tered only by experience.

9. When decolorized to the correct point, usually
just beyond the point w^hen the color comes from the
film into the differentiating fluid as the slide is dipped
up and down, rinse in tap water, pass through
graded alcohols and into carbol-xylol (or similar
clearing agent), xylol, and mount in balsam.

Do not allow the film to dry at any stage.

This staining procedure is not easy and many poor
specimens to each good one will be obtained, par-
ticularly until the technique is mastered and is being
fairly constantly practiced.

36 PROTOZOAN PARASITISM

Shorter methods of stainmg may be used, such as
Mayer's ''Haemalum," but the details are not as
well presented as in the iron-haematoxylon.

Mayer's Haemalum may be made by dissolving 1
gram of haematoxylon crystals in 1000 cc. of dis-
tilled water and adding 50 grams of potash alum and
0.2 gram of sodium iodate.

The fixed and washed slide preparations from the
fourth step in the technique given above for the
iron-haematoxylon method should be placed in this
stain for 15-20 minutes. The slides are then washed
in tap water until blue in color, with the water run-
ning or being frequently changed. The preparations
are dehydrated, cleared and mounted as above.

The iron-haematoxylon staining is best for care-
ful study of nuclear and other structural detail.
Mayer's Haemalum is much shorter and less difficult
and is sufficient for identifying the organisms.

Study of fresh unstained materials for the active
amoebae is only a preliminary step in the identifica-
tion of the organisms. In the hands of an experi-
enced protozoologist it may be conclusive in the
majority of instances but it is reasonably certain that
even the expert will err at times. Study of prepara-
tions stained by the iron-haematoxylon method will
usually lead to accurate identification in the vegeta-
tive phase by the expert protozoologist. These
measures, however, are not to be depended upon in
less expert hands. The amoebae are frequently in
such active form as to render unreliable an opinion as

OF THE ALHIENTARY TRACT 37

to the species by any except the most experienced
and at times by them, while this painstaking method
of staining is usually not attended by striking success
except by one constantly practiced in it.

It is considered a good practice in medical diagnosis
to have some routine procedure like the following:

Unless there is diarrhoea, administer a saline
cathartic to produce a liquid stool. Oil renders a
specimen unfit for examination, both fresh and
stained. Examine immediately, i.e. while fresh and
without allowing the stool to cool, portions from dif-
ferent parts of the stool, as described above. Use a
mechanical stage so as to be certain of covering the
whole preparation. There has been much said about
the frequency with which amoebae are not to be
found in the stool of an infected person and it is well
know^n that the fifth or sixth examination of a stool
may show an amoeba for the first time. How^ever,
a fresh liquid stool, produced and examined under the
above conditions, will seldom fail to reveal any ex-
isting infection. If two or three repetitions of the
procedure fail to show any protozoon it may be or-
dinarily accepted that there is no infection.

So much emphasis has been placed upon the neces-
sity for a number of stool examinations before a
negative may be declared that it is often considered
by practicing physicians that stool examination for
protozoa is an impractical procedure.

For routine practice one or two repetitions of a
negative finding, after two or three days, under strict

38 PROTOZOAN PARASITISM

conditions as above may reasonably exclude pro-
tozoal infection.

The finding of an active amoeba by such examina-
tion is merely the first step. It must be now identi-
fied. If the case is one of clinical active intestinal
amoebiasis, especially with blood stained mucous
stool, and an amoeba is found, of active progressive
motility, without bacteria and other solid bodies,
such as yeasts or crystals, but perhaps containing
red blood corpuscles, the presumption is that it is
Endarnoeha histolytica. This is allowable because
it is advisable to get the individual on proper treat-
ment and the diarrhoea may prevent the appearance
of cysts for an indefinite period. In such a case
the cysts may be hunted when the stool begins to
form.

In other cases search must now be instituted for
the cyst, which may or may not be found in a
purged stool. If it is not, a formed stool must be
obtained.

Study of amoebic cysts for diagnostic purposes in
medical practice amounts to looking for that of End-
amoeha histolytica to the exclusion of all others.
Amoeba cysts in the stool are rounded, glassy or
hyaline bodies, easily overlooked, sometimes very
numerous, sometimes not.

Search for them is facilitated by mixing the particle
of stool on a slide with an iodine solution, such as
Gram's iodine (iodine 1 part, KI 2 parts, water 100
parts). This stains them various shades of brown

OF THE ALIMENTARY TRACT 39

and makes them more conspicuous. It also allows
the nuclei to become visible as colorless rings against
the yellow-brown background.

When a suspicious body is located with the low-
power lens, the higher dry magnification will usually
reveal its structure.

If the cysts found show four round nuclei with tiny
central karyosome it is Endamoeha histolytica. The
main confusion is with the cyst of Endamoeha coli;
it has eight nuclei. This simple mathematical propo-
sition, so difficult to get across to medical labora-
torians, is the most important thing in the diagnosis
of amoebiasis, it is the sole conclusive point in the
chronic case, practically considered.

Of course, there may be a mixed infection and one
should not cease search for this cyst until satisfied of
its absence, regardless of what else may be found.

In addition to Endamoeha coli much confusion
arises from that ubiquitous stool inhabitant, Blasto-
cystis. A little experience, however, will lead one to
pass this by as he would foreign particles. Because
of this common confusion consideration of Blasto-
cystis in an appropriate place is given in this book,
although it is not a protozoon. Suffice it to say here
that it is commonly very numerous in a liquid stool,
is very common in any, is of widely variable size,
rounded, ovoid, or elongate. It usually has a trans-
parent rim sharply defined from the main body,
which is hyaline, stains brown with the iodine and
contains no nuclei like those of the amoebae. Study

40 PROTOZOAN PARASITISM

of illustrations of this body should lead immediately
to its recognition.

For certainty in eliminating the possibility of End-
amoeha in the stool, more than these fresh immedi-
ately examined preparations is necessary. Perma-
nent stained specimens, by the haematoxylon
methods previously described, are recommended by
James (1927) and other experienced workers, on the
contention that amoebae may frequently be found
in these preparations when not in others and that
they may be more accurately identified.

Consequently, the writer desires to recommend
such a measure when Endamoeba histolytica has not
been found in a suspicious case or when it has been
identified by any measure except actual counting
of characteristic nuclei in the cysts. It is freely
confessed, however, that his ideas do not follow this
far, in consideration of what is simple and therefore
practical and likely to be done in medical practice
outside of centers where the ultimate may be con-
sistently followed.

It is emphasized that only a few are considered
competent to identify anything but the cyst, and
that familiarity with this stage should be stimulated
with medical laboratorians.

Neither are cultures to be relied upon in any but
expert hands, although some have recommended
them for diagnosis in amoebic and other protozoon
intestinal infections. With the experienced and ex-
pert cultures may pick up an infection otherwise

OF THE ALIMENTARY TRACT 41

missed With others they are unreliable and will un-
doubtedly lead to errors.

Methods of concentration of the cysts in the stool
so that they may be more readily found are strongly
recommended by some. For this purpose the pro-
cedure of Yorke and Adams (1926) is recommended.

About 10 grams of the feces, thoroughly mixed with
200 cc. of distilled water, is allowed to stand for 20-
30 minutes. The supernatent fluid is poured off and
distilled water to 500 cc. added. After standing
overnight in the ice box the supernatent fluid of this
is decanted and the sediment saved. This is washed
once with distilled water and centrifugalized at about
2000 revolutions per minute for two minutes. The
sediment is suspended in a solution of sucrose of about
1.080 specific gravity in about the proportion of 2
cc. of sediment to 14 cc. of sucrose solution. This
mixture is next centrifugalized at 3000 revolutions
per minute for 3 minutes. The supernatent solution,
which contains the cysts, is concentrated by dilution
with three volumes of distilled water and centrifugal-
izing at 2000 revolutions per minute for 2 minutes.
A small portion of the sediment is examined for the
cysts in microscopic preparation with iodine solution.

Without the intention of detracting from the ab-
solute value of permanent staining, concentration
methods and cultures, and recognizing their full
value where they may be used in a competent way,
particularly for uncovering amoebic infections when
the parasites are sparse, it is the desire of the writer

42 PROTOZOAN PARASITISM

at this time to encourage the performance of a simple
procedure which will suffice in a practical way in the
practice of medicine and will at least vastly improve
upon present practices and conditions.

For this purpose it is desired to summarize the
following procedure for a routine :

1. When a formed stool is up for examination, as
it commonly is, make slide preparations with salt
solution from various portions and look for motile
and encysted forms. If motile forms are found
search for the cysts. Search for cysts with slide
preparations in the iodine solution. When found
count the nuclei by fine adjustment manipulation of
the high dry lens. If there are four characteristic
nuclei report it Endamoeba histolytica. If only ac-
tive forms are present, so report them and ask for
continued stool examination until the cysts are found.

2. When a diarrhoeal stool is up for examination,
look also for the cysts. Usually they will not be
found. If there is an actively traveling amoeba
which does not contain large vacuoles with bacteria
and other foreign objects, but some contain red blood
corpuscles, with clear ectoplasm and pseudopodia,
and granular endoplasm, report it as a motile amoeba,
possibly Endavioeha histolytica, and ask for con-
tinued stool examination for cysts.

As a routine practice, except in case of diarrhoea,
ask for stools produced by saline purgative, not oil,
and search for motile forms and cysts. If only motile

OF THE ALIMENTARY TRACT 43

forms are seen, report it so and ask for continued
examination for cysts.

3. When not positive of the identification of an
amoeba, either motile or cyst, or when none is found
where it is judged it should be, make slide prepara-
tions, at least twelve, according to the instructions
of steps one, two, three, and up to the 90-95% alco-
hol of step four in the iron-haematoxylon staining
technique previously given. Then seal in a con-
tainer of alcohol and send to a recognized protozoolo-
gist for completion of the stain and search for and
identification of the amoeba.

Where facilities and personnel of medical labora-
tories is sufficient the more elaborate procedures
should be appropriately carried through.

CHAPTER IV

The Amoebae (Continued)

Endamoeba histolytica. Prevalence, Distribution and
Transmission. Experimental Information. Cultivation.
Habitat and Effects. Chronic Intestinal Amoebiasis.
Acute Amoebic Colitis (Amoebic Dysentery). The Stools
of Dysentery. Treatment.

ENDAMOEBA HISTOLYTICA.

This true parasite, of known pathogenic activity,
is the most important of the protozoa of the alimen-
tary tract. Discovered by Losch (1875), it has been
extensively studied by numerous observers and our
information about it is probably more definite than
with any of the other alimentary tract protozoa.

In active stage it is usually of rather characteristic
appearance. Rounded up it measures 20 to 30 mi-
crons in diameter. When motile it travels rather
actively and steadily, the ectoplasm in pseudopodia,
at the forefront, the endoplasm with food bodies, if
present, following, the flow of the whole organism
being somewhat like that of a drop of liquid on an
incline to which it adheres somewhat. The ecto-
plasm is comparatively clear, in pseudopodia when

44

OF THE ALIMENTARY TRACT

45

motile, as a rim when rounded. The endoplasm is
granular but not coarsely so as in some of the other
amoebae. In this part of the body may be seen red
blood corpuscles from the host, in amoebic dysentery.
It does not contain bacteria and other solid food bod-

FiG. 1. — Endamoeha histolytica.

A, trophozoite with ingested red blood corpuscles. B, precystic
C, D and E, cysts with one, two and four nuclei. Draw-
ings of specimens stained with iron-haematoxylon. x 2000.

ies in this natural state, although it may in culture,
since these objects do not ordinarily form part of the
food of this amoeba. The nucleus is invisible in the
unstained specimen.

Stained by the iron-haematoxylon method, with
light eosin counterstain, the ectoplasm is very light

46 PROTOZOAN PARASITISM

pink or practically unstained, the outlines of the
organism being somewhat indistinct at times. The
endoplasm is a deeper pink, granular, and if red blood
corpuscles are present they are rounded bodies re-
taining the black stain in proportion to the differentia-
tion. The nucleus is here seen in characteristic form,
from 4 to 7 microns in diameter, depending on the size
of the amoeba. It is round, has a delicate but defi-
nite rim and a linin network, more imaginary than
distinct as a common thing. Small chromatin gran-
ules are evenly distributed on the inner aspect of
the rim and the karyosome is a minute chromatin
body, centrally placed and surrounded by a ''halo,"
which is more or less distinct. Such a stained am-
oeba may be readily identified.

The cysts vary in size according to the race, the
different races averaging 6.6, 8.3, 11.6, 13.3, and 15
microns, as measured by Dobell and Jepps (1917-
1918). They are round glassy or hyaline bodies in
the fresh unstained state. With careful adjustment
of the lighting the nuclei may be brought out as deli-
cate refractive rings, four in number in the developed
cyst. The chromidial bodies, characteristic of the
species, may also be made out in such specimens by
careful adjustment of the light. The main differen-
tial measure, upon which cysts of this amoeba may be
identified immediately, without staining, is that of
counting the characteristic nuclei.

In the iron-haematoxylon preparation these cysts
are well stained, the cytoplasm light, the nuclei of

OF THE ALIMENTARY TRACT

47

the typical form described in the trophozoite, the
chromidial bodies black or dark brown bars or rods
with blunt or tapering ends.

Fl(i.2. — Kiuldinoi h(i Itlslolj/lica.

A, precystic stage. B, cyst with two nuclei and chromatoidal bar.
C, cyst with four nuclei and chromatoidal bar. D, trophozoite with
ingested blood corpuscles. Photomicrographs of specimens from
man. A, B and C from chronic intestinal amoebiasis, D from
amoebic dysentery, stained by iron-haematoxylon. x 1500.

PREVALENCE, DISTRIBUTION AND TRANSMISSION

Endamoeha histolytica, once thought to be of im-
portance only in the tropics, is of world-wide distribu-

48 PROTOZOAN PARASITISM

tion. In temperate or colder regions its incidence is
usually less, but it has been found wherever search has
been made for it. The reported incidence in different
surveys varies widely, from around 1% to 20% and
more, the variation in reliable studies apparently de-
pending largely on the nature of the examined people,
as to the sanitation of their environment and whether
they are well or subjects of intestinal disease. The
greater incidence is naturally where the protection of
man from the excreta of his kind is poorest^ this
usually being the case in tropical and subtropical
regions. In institutional life, with its close personal
contact, it is likely to be comparatively high. In
rural districts without modern facilities for sewage
disposal it is also apt to be high. In modern com-
munities with regulated sewage disposal, care of milk
and other food, and water, it is low. Through a
country like the United States it will probably aver-
age less than 10%. In the experience of the writer
the incidence in the population of the modern city
and town is nearer 3%. The food handler carrier
and close personal contact with infected persons are
undoubtedly the main means of spread of the parasite
among the inhabitants of districts of good sanitary
facilities. Prolific spread and the production of epi-
demics of disease by it are not at all likely, although
Craig (1026) shows that epidemics in special groups,
such as troops, exposed to massive infection under
certain conditions may occur. The concern of some
about the danger to the people of this country from

OF THE ALniENTARY TRACT 49

returning soldiers after the last war did not seem
justifiable and has apparently not proven warranted.
Since the cyst is the only infective stage of the
parasite, prevention of spread of it depends upon
preventing this body from reaching the mouth of
man. The control of flies and the protection of ex-
creta and food from them is important. In regions
where human excreta are used as fertilizer uncooked
vegetables are dangerous. Public food handlers of all
sorts may act as carriers and well regulated protection
should involve examination of them for this organ-
ism. It is the apparently healthy carrier, not the
person with amoebic dysentery, who is the dangerous
factor in transmitting Endamoeba histolytica. Pro-
tection against this amoeba involves such sanitary
practices as are used against typhoid infection, in-
cluding consideration of the carrier. Walker (1911)
names those who have recovered from amebic dysen-
tery but still harbor the organism ^'convalescent car-
riers" and the person who has the parasite without
having suffered from the acute disease the '^contact

carrier."

As previously referred to, the writer (1915) dis-
covered a focus of natural infection of wild rats with
an amoeba indistinguishable from Endamoeba histo-
lytica in a house occupied by negroes, where a cellar
was used as a ''privy." From this habitation at least
two cases of amoebic dysentery were traced. Brug
(1918) found natural infection of two wild rats in
Java. Chiang (1925) also discovered in laboratory

50 PROTOZOAN PARASITISM

rats a natural intestinal infection with an amoeba
agreeing very closely in its morphology with End-
amoeba histolytica of human origin. These three,
as well as Kessel (1923), also infected rats by feeding
human feces containing the cysts. The rat is an
omniverous animal and will eat human feces even
when other food is available. In many places this
animal has access to human excreta and opportunity
to contaminate human food and eating utensils with
its own excreta. These opportunities are uncommon
under modern housing and sanitary conditions, but
there are many places where they are not uncommon
and these are the places where intestinal amoebiasis
is usually most common and important. Until
studies are made in such regions and it is shown that
the rat does not transmit the infection in nature, this
animal must be under suspicion as a possible carrier.

Under similar suspicion is the domestic pig, since
Kessel (1928) has reported that this animal may
naturally and experimentally harbor this amoeba for
about six weeks. In some quarters the pig is in close
contact with human beings and is allowed access
to human excrement.

Using the culture method to prove the viability of
cysts, Yorke and Adams (1926) found that Endam-
oeba histolytica cysts commence to die fairly rapidly
in feces at laboratory temperature (16-20°C.) for
three or four days and that all died within ten days.
This was also the case at 0°C. They found, also,
that the cysts survive a temperature of 45 °C. for

OF THE ALIMENTARY TRACT 51

thirty minutes but are killed within five minutes at
50°C. Ordinary chlorination of water, such as is
commonly used in public water purification was with-
out effect upon them but they were fairly sensitive
to bichloride of mercury (1 to 2500), formaldehyde
(0.5%), carbolic acid (1.0%) and lysol (1.0%).
Boeck (1921), using eosin absorption as a test of the
viability of cysts, indicated that this phase of End-
amoeba histolytica survives for months in plain
water.

Whether either of these methods, and which the
better, suffices to determine when protozoan cysts
are no longer able to hatch living organisms in the
intestine remains to be conclusively shown.

Stools, water, and other liquids and moist materials
containing Endamoeba histolytica cysts may be con-
sidered infectious for some time at least. Contam-
inated water is not freed of its infectiousness during
this time by ordinary chlorination. The heating of
foods which may have been exposed to contamination
to 55°-60°C., the pasteurization of milk, similar
heating or boiling of drinking water, should control
the dissemination of the infection, where proper sew-
age disposal is not done, except the hand-to-mouth
carrier transmission. When proper sewage disposal
is not available, fecal matter should be disinfected
by an agent of known amoebicidal properties (Craig
[1926] recommends mixing the stool in cresol 1 to 200
for 15 n>inutes) and fly control and screening should
be carefully exercised. Where human excreta is used

52 PROTOZOAN PARASITISM

for fertilizing garden stuff, fresh uncooked vegetables,
especially those kept moist, should not be eaten.
Possibly refrigeration of such articles for a period of
time, yet to be positively determined, sufficient for
the cysts to die, may render them safe for consump-
tion.

EXPERIMENTAL INFORMATION

Experimental infection of other animals with End-
amoeha histolytica from man has been done on nu-
merous occasions and has proven of great value in
determining the manner of occurrence of the infec-
tion and the nature of the disease produced by it.

The most commonly used animal is the cat, kittens
being susceptible to the infection on injection of
material containing the amoeba by rectum, less so on
feeding the cysts. The lesions produced in such
a manner are similar to those of amoebic dysentery
in man, including the occasional occurrence of am-
oebic abscess of the liver. Since Hlava (1887) first
produced this experimental infection it has been
frequently done, the early experimenters being Kar-
tulis (1891), Kovacs (1892), Quincke and Roos
(1893), and Kruse and Pasquale (1894).

Several workers, including Losch (1875), Hlava
(1887), Kruse and Pasquale (1894), and others, have
infected dogs.

Guinea pigs have been experimentally infected by
Baetjer and Sellards (1914) and Chatton (1917).

OF THE ALIIMENTARY TRACT 53

Thompson (1926) produced experimental infection
of rabbits.

Lynch (1915 and 1928), Brug (1919), Kessel
(1923), and Chiang (1925), have brought about ex-
perimental infection of rats by feeding the cysts.

Fig. 3. — Experimental Amoebic Ulcer of the Colon of a Rat.

While the disease produced in kittens is similar
to amebic dysentery in man, it is commonly very
acute and it is practically always fatal. There is
not the non-dysenteric phase as in man, consequently
there is no encystment of the amoeba and this animal

54 PROTOZOAN PARASITISM

cannot be a transmitter of the infection either natu-
rally or experimentally. The amoebae can be trans-
ferred from cat to cat only by rectal injection of the
living trophozoites.

The experimental disease in the guinea pig has
been the formation of tumor-like growth of the in-
fected wall of the caecum.

In rats there is the acute colitis corresponding to
amoebic dysentery, as well as the development of the
non-dysenteric carrier, with minute ulcers of the
mucosa of the colon or without any discovered lesion.

CULTIVATION

There have been a great many unsuccessful at-
tempts to obtain growth of Endamoeba histolytica
outside of the animal intestine. Until very recently
a good deal of confusion existed as to whether or
not it had been done. Certainly a number of reports
of its cultivation are erroneous, the amoebae grown
being free-living forms accidentally encountered in
the material used.

In the light of subsequent successes it appears that
the first cultivation of Endamoeba histolytica, or
any true parasitic amoeba, was done by Cutler
(1918). Several workers failed to repeat Cutler's
success, notably Dobell (1919), and Wenyon, and,
consequently, it was taken as other reports had been.

Following the artificial cultivation of Endamoeba
barreti by Barret and Smith (1923), comes the re-

OF THE ALIMENTARY TRACT 55

peatedly confirmed and elaborated work of Boeck and
Drbohlav (1925), and Endainoeba histolytica is now
subject to laboratory growth and study in artificial
media, although not in pure culture free from bac-
teria.

The medium used by Boeck and Drbohlav, as im-
proved by Drbohlav, is prepared as follows:

Take four eggs, wash and brush with alcohol, break
into a sterile flask containing glass beads, add 50 cc.
of Locke's physiological solution and shake until the
mixture is well broken up. Slant in test tubes to
the length of 1 to 1% inches and coagulate by heat
in an inspissator at 70° C. Transfer to the auto-
clave and sterilize for 20 minutes at 15 pounds pres-
sure. Cover the solidified egg to a depth of about
1 cm. above the slant with a mixture of 1 part of
sterile inactivated human blood serum in 8 parts of
sterile Locke's solution. Instead of the blood serum
mixture 1% solution of crystallized egg albumin in
Locke's solution may be used. Either of these mix-
tures may be sterilized by passing through the Berke-
feld filter. Their sterility should be tested by inocu-
lation and incubation of bouillon tubes or agar plates.

The Locke solution is made as follows:

Distilled water, 1000 cc; NaCl, 9.0 gms.; CaCls,
0.2 gms.; KCl, 0.4 gms.; NaHCOs, 0.2 gms.; Glu-
cose, 2.5 gms. Sterilized either in the Arnold or
autoclave.

The amoebae do not penetrate the solid medium
but occur in the sediment of the lower part of the

56 PROTOZOAN PARASITISM

surface fluid. The cultures should be incubated at
37° C. and transplanted on the second day, when the
amoebae are most numerous.

Kofoid and Wagener (1926) substituted for the
human blood serum in this medium rabbit, rat, cat,
and guinea pig blood. Their most satisfactory sub-
stitution was defibrinated rabbit blood, used 0.5%
in Locke's solution.

Craig (1926) succeeded in growing Endainoeha
histolytica in seven parts of 0.85% sodium chloride
solution and one part of inactivated human blood
serum.

As Smith and Barret (1928) call to attention,
Craig's medium is a variation of a mixture of blood
serum which they, or one of them (Barret, 1921;
Barret and Yarbrough, 1921 ; Barret and Smith, 1924;
Barret and Smith 1926) have used to cultivate Blasto-
cystis hominis, Balantidium coli, Endamoeha bar-
reti, and Endamoeha ranarum. They suggest that
variations of the strength of this simple medium may
prove satisfactory for cultivation of a large range of
parasitic protozoa.

The author has used it for more than ten years,
along with similar mixtures of pleural and abdominal
cavity fluids for cultivating several flagellates, as well
as Blastocystis. Some of this work has been pub-
lished previously and will be referred to under appro-
priate subjects; the first was not reported.

There appear to be unsolved difficulties in all of
these methods of cultivation. In the writer's labora-

OF THE ALniENTARY TRACT 57

tory notes of 1922 occur observations of apparent
multiplication of Endamoeba histolytica and Etid-
amoeha coli in 1 to 5 serum mixture with 0.9% so-
dium chloride solution, incubated, at 37°C. This
cultivation was ungovernable, however. It was a
hit or miss procedure. Subculture was, also, un-
governable. The organisms multiplied for two or
three days and then gradually disappeared by the
fourth or fifth. The undeterminable and ungov-
ernable factors were thought to be the bacterial con-
tent of the cultures and the changing reaction of
the media.

It has appeared to the writer in working with the
various described media for cultivation of alimentary
tract protozoa that their reliability is by no means
comparable to that of bacterial cultures. The con-
tent and reaction of the media is controllable only
primarily.

The subsequent changes in the media must be
variable and uncontrollable, as are the contaminating
bacteria in them. Apparently identical media will
grow them at times and will fail at others. Until
the bacterial growth can be eliminated or controlled,
cultivation of these protozoa will not be satisfactory
and the benefits from such procedures will not be
fully realized, although in the hands of some (Craig,
1928, and Craig and St. John, 1927) cultivation of
Endamoeba histolytica has been reliable enough for
recommendation as a measure of diagnosis of the
infection.

58 PROTOZOAN PARASITISM

HABITAT AND EFFECTS

When the cysts of Endamoeba histolytica are swal-
lowed by man they pass unharmed to the intestine,
where the cyst is dissolved or ruptured and the tropho-
zoite liberated. The organism is probably liber-
ated as a four nucleated amoeba and then completes
the division. The daughter amoebae pass down
to the large intestine, the natural habitat. Growing
to mature size they become seated largely in the por-
tions of this tract in which the content accumulates
and remains longest, notably the caecum and the
descending colon, although the whole of the colon
may be involved in the infection, especially in am-
oebic dysentery, and there may be ulcers on and
above the ileo-caecal valve.

Depending upon unknown factors, involving the
capabilities of the parasite for invasion of the tissue
as balanced against the resistance of the host to it,
the results of the infection may be chronic intestinal
amoebiasis or clinical amoebic dysentery, the for-
mer more commonly.

The manner of penetration and invasion of the
wall of the intestine is subject to some debate, as to
whether the amoebae pass through an intact mucosa
between living epithelial cells or produce destruction
of epithelium and a gateway for their admission.
For many years it was believed by some that they
gained entrance through lesions of other primary
production. This is evidently not essential and they

OF THE ALIAIENTARY TRACT

59

Fig. 4. — Acute Amoebic Colitis.

Small unVlermined ulcers. (U. S. Army Medical Museum No.
39,113. Also from Haughwout and Callender.)

60 PROTOZOAN PARASITISM

are undoubtedly primary pathogenic organisms, ca-
pable within themselves of invading the wall, al-
though the host is commonly able to limit the extent
of penetration. Whether they may be purely lumen
dwellers is yet unsettled. Previous opinions on this
question, even by those who may speak most authori-
tatively, are subject to error in the unknown. In
considering the possibility it should not be forgotten
that the amoeba may be grown apparently indefi-
nitely as a "lumen dweller" in a culture tube. It
should also be borne in mind that pathological find-
ings in the intestine at autopsy in the hands of care-
ful and experienced pathologists and in large services
are not in proportion to the common relatively high
incidence of the infection as reported from stool
examination. Is it possible that even minute lesions
which must be so commonly present unless this am-
oeba is frequently a pure lumen dweller should have
been so completely overlooked?

The writer hesitates to acknowledge that in a con-
siderable autopsy experience a condition in which
there existed a special interest was not found. And
yet such must be the case if Endainoeha histolytica
always invades the intestine wall. Naturally the
intestine has not been minutely examined always,
nor have a great number of microscopic sections been
done as a practice, but recently, at any rate, extra
care has been exercised and if a common intestinal
lesion, even small, has been overlooked it will take
virtual serial section to reveal it. In this connection

OF THE ALIAIENTARY TRACT

61

Fig. 5. — Amoebic Colitis.

Nest oi Endamoeha histolytica in the bottom of a gland crypt of
the mucosa. Photomicrograph x 180.

it must be recorded that the writer's autopsy service is
largely af negroes and that the incidence of the infec-
tion among them in this locality is unknown.

62 PROTOZOAN PARASITISM

The contention of anything in the region of a con-
stant intestinal invasion in the very large number of
infected persons, if this itself is correct, remains to be
proven.

The finding of an amoeba indistinguishable from
Endamoeha histolytica as, apparently, a lumen
dweller in the rat, must also be considered in an ar-
gument at the present.

The amoeba does not encyst within the tissues but
this process occurs in the lumen as the organisms are
carried down with the intestinal content to the lower
bowel, where inspissation takes place. As they pro-
ceed to encystment they become smaller and less
active. As cysts they pass out with defecation to
become the form transmissible to a new host.

It is not known whether they multiply in the colon
from their own cysts, that is, whether excystment
takes place here. Ordinarily at least it appears that
division of the trophozoites is the manner of increase
and that this occurs mainly in the lumen and in the
glands.

The properties of the amoeba which enable it to
invade the tissue are its physical ability to squeeze
between adjoining cells and, particularly, its cytoly-
tic action upon cells with which it comes in contact
(Craig, 1928). James (1927) (Scientific exhibits,
Amer. Med. Ass'n) has shown that Endamoeha histo-
lytica is capable of pushing its way between the
epithelial cells of an intact mucosa. How common or
important this is it is impossible to say. In the

OF THE ATJMENTARY TRACT

63

I

y^m. -.-

I

% k .. '• J 1.

Fig. 6. — Amoebic Colitis.

Endamoeba Jiistolytica within a venule and in tissue spaces of
the submucosa of the colon. Photomicrograph x 470.

writer's specimens from human amoebic colitis pene-
tration of the surface epithelium has not been ob-
served (Lynch, 1920). The amoebae do not occur
in the superficial tissues of the mucosa. They invade
the mucosal glands and single organisms may be seen

64 PROTOZOAN PARASITISM

at different locations here. At the bottom of the
crypts the amoebae appear to multiply, nests of
them may be seen, and here the epithelium undergoes
necrosis and dissolution, although in the upper part
of the gland it may be intact and apparently healthy.
Through the denuded base of the gland the amoebae
penetrate and move to the deeper tissues, traveling
through the lower tissues of the mucosa, the muscu-
laris, the submucosa, and possibly through the entire
wall. They spread laterally in the submucosa par-
ticularly, thus producing the characteristic lesion of
amoebic dysentery with undermined mucosa, which
may itself be more or less intact on the surface.

The resistance to their advance offered by the host
is inflammatory locally. That there may be a hu-
moral antagonism is indicated by Craig's (1928)
complement fixation and Wagener's (1924) precipi-
tin experiments.

The local inflammation includes congestion, ex-
udation of plasma, infiltration of mononuclear leuco-
cytes and proliferation of fibrous tissue. After ex-
posure of ulcerated tissue to the intestinal bacteria
the picture becomes confused by reaction against
such infection.

The cytolytic activity of the amoebae is not con-
spicuous as a rule. As the parasites advance through
the tissues, they may be seen rather far afield, where
there is little evidence of tissue destruction or reac-
tion. The necrosis and ulceration occurs behind
them. Thrombosis of small blood vessels, which

OF THE ALOIENTARY TRACT

65

Fig. 7. — Amoebic Colitis.

Undermining submucosal ulcer with sinus to the surface.
Photomicrograph.

occurs as they are invaded, may be an important fac-
tor in the ulcer development.

Although the organisms invade the lymph spaces

66

PROTOZOAN PARASITISIM

and vessels, there is little tendency to infect the
lymph follicles of the intestine or the lymph nodes
of the mesentery. James (1928) found them in a

I I I IP MM| l IM ill I

Fig. 8. — Amoebic Colitis.

Endamocha histohjtica within small blood vessels of the siib-
miicosa, two in upper, one in lower, with thrombosis. Photomicro-
graph X 475.

lymph follicle of the human intestine, and Thomp-
son (1926) has shown some invasion of lymplioid tis-

OF THE ALIAIENTARY TRACT

67

Fig. 9. — Amoebic Colitis.

Large group of Endamocha histolytica in a lymphatic vessel of
the siibmiicosa of the colon, with a few in the surrounding tissues.
Photomicrograph x 195.

68 PROTOZOAN PARASITISM

sue of the intestinal wall in experimental infection
of the rabbit.

Their invasion of the blood vessels of the involved
intestine explains the most common extension which
occurs, that to the liver. Here some think they pro-
duce a not uncommon hepatitis. The well-known
amoebic lesion in this organ is the abscess, single or

Fig. 10. — Amoebic Abscess of Liver.
(U. S. Army Medical Museum Specimen.)

multiple. The characteristic pathology of amoebia-
sis is in evidence in the abscess of the liver. The cen-
ter of the focus of implantation undergoes necrosis
and destruction, there is a mild type of reaction, in-
volving hyperemia, plasma exudation, fibrin deposit,
some mononuclear infiltration, with a few polymor-
phonuclear leucocytes, there being no gross or micro-
scopic pus as seen is abscesses of bacterial production,

OF THE ALIMENTARY TRACT 69

unless there occurs a secondary infection, no active
abscess wall formation with conspicuous congestion,
leucocytosis or fibrous tissue proliferation. The
more chronic, the longer standing, the abscess, the
more fibrosis occurs about it.

The amoebae spread peripherally between the
cords of liver cells and as they advance the zone of
liver cell degeneration and necrosis progresses until
a large abscess reaching the surface may be produced.
The extension of the process may lead to rupture
into the abdominal cavity or even through the dia-
phragm into the chest and lung. Councilman and
Lafleur (1891) in a masterly study of the pathol-
ogy of amoebic dysentery, which placed intestinal
amoebiasis on a definite pathological basis, de-
scribe a diffuse degeneration and necrosis of
liver cells, especially around the central lobular
veins, unrelated to the presence of the amoeba.
This they believe to be the consequence of absorp-
tion of products of the amoebae in the intestine
ulcers. This may be the hepatitis spoken of by
clinicians during amoebic dysentery without liver
abscess.

Abscess of the lung by direct extension is the next
most common foreign extension, although blood born
organisms may be transferred to these organs and to
other parts, notably the brain. Wherever the amoe-
bae go the characteristic lesion seems to occur; as
the organisms spread the tissues become necrotic
behind them, liquifying and producing the abscess

70

PROTOZOAN PARASITISM

without leucocytes. The reaction to them is mild
congestion, plasma exudation, fibrin deposit, mono-

FiG. 11. — Amoebic Abscess of Liver.
(U. S. Army Medical Museum No. 44,739. Photomicrograph.)

nuclear cell infiltration, connective tissue prolifera-
tion.

Warthin (1922) has reported this amoeba in the

OF THE ALIMENTARY TRACT 71

testis and its tract and Warsley and Bateman (1924),
Craig (1911), Macfie (1916) and others have ob-
served it in the urine. Kofoid (1925) and others
have reported finding Endamocba histolytica in duo-
denal drainage from cases of intestinal amoebiasis
without liver abscess.

While it may escape the bounds of the intestine and
the portal circulation, such accidents are unusual.

The finding by Kofoid and his co-workers of bodies
which they took to be Endamoeba histolytica in the
joints of arthritis deformans and the lymph nodes of
Hodgkin's disease has not been generally accepted
as correct. The writer has had no opportunity to
attempt confirmation of their observations except in
fresh lymph nodes of Hodgkin's disease. There no
amoeba was found. Kofoid identified the cells which
he found in these tissues by the number of chromo-
somes in the nucleus and by the mitosis of the divid-
ing cell. One hesitates to question the correctness of
observation by a protozoologist of Kofoid's calibre
but there are so many pitfalls in such work that both
biologists and pathologists will await further evidence
and confirmation before passing judgment. The na-
ture of the lesions in both cases, especially the char-
acter of the reaction in Hodgkin's disease, and the
dissimilarity to the characteristic amoebic lesion,
makes pathologists immediately skeptical that these
diseases could be of amoebic origin.

It seems clear that the disease produced by this
organism is virtually limited to the large intestine,

72 PROTOZOAN PARASITISM

with direct extension to adjacent tissues, occasional
excursion to the liver, and rarely accidental metas-
tasis to other tissues.

Fig. 12. — Amoebic Colitis.

Group of Endamocha histolytica within the tissues between the
muscle coats of the colon. Photomicrograph x 475.

Local extension deep into the wall of the intes-
tines is common in generalized colonic infection, usu-
ally with dysentery. Sometimes involvement of the
peritoneum allows bacterial invasion to this tissue
with local or general peritonitis but peritonitis is

OF THE ALIAIENTARY TRACT

73

more commonly the result of rupture of the ulcer
through the intestme wall with escape of the content
of the bowel.

Direct extension of the ulcers into the retroperi-

FiG. 13. — Amoebic Colitis.

Three amoebae within a tissue space in the subperitoneal coat of
the colon. Photomicrograph x 475.

toneal tissues, instead of through the peritoneal cov-
erings, is not uncommon, with the progression of
tunnelling suppurative sinuses extensively through
the retroabdominal tissues, involving adjacent or-

74 PROTOZOAN PARASITISM

gans. With this there is developed bacterial infec-
tion, a septic state, and death. This sort of extension
has been more common in the writer's experience than
others, even to the liver.

The disease of the intestine may be divided into
an acute and a chronic stage, the latter by far the
more common, the former the typical condition of
amoebic dysentery.

It is convenient and permissible, both from the
pathologic state and the clinical aspects, to divide
intestinal amoebiasis into two phases, chronic in-
testinal amoebiasis and amoebic dysentery or acute
amoebic colitis.

CHRONIC INTESTINAL AMOEBIASIS

This is the most common phase of the disease and
covers, in our present knowledge, the carrier states.
During its course or as its termination may occur a
flare into the acute state of amoebic dysentery. Dur-
ing its course may also occur liver abscess, or rare
accidental metastases elsewhere.

The clinical state is confused and not subject to
a positive diagnosis without finding the amoeba.

Those of wide experience with the disease, notably
James (1928) and Craig (1928), are convinced that
it is of very important proportions in the class of
those who suffer from long continued ill health with
confusing symptoms of many kinds but particularly
relating to the intestinal tract, ''indigestion" as the

OF THE ALIMENTARY TRACT 75

Although attacks of diarrhoea or even dysentery,
alternating with periods of constipation, may be dis-
covered in the personal history, they may not be
more conspicuous than in other people of similar ail-
ments. Constipation appears to be the rule of the
intestinal dysfunctions. \^ague abdominal pains,
heaviness, minor tenderness over the colon, especially
the caecum, flatulence, gaseous eructation, are the
common abdominal complaints. Generally there is a
condition of under weight, a ''tired feeling", a lack
of energy. There are headaches and possibly joint
aches. The state of ''neurasthenia" is the type, with
subnormal temperature, low tension, cardiac irregu-
larity, etc.

All of which furnishes a picture which is very com-
mon to the practicing physician.

The state is thought to be one of "toxemia" and
Craig's complement fixation is an evidence of hu-
moral absorption and antibody production.

Diagnosis is to be made by finding the amoeba in
the stool, possibly only by repeated examination.

The pathologic state in this condition is supposed
to be that of the small mucosal ulcer previously de-
scribed. It appears that these ulcers may be only
of microscopic proportions or, at least, barely visible
on careful search. Presumably they develop slowly,
heal, and develop elsewhere. These flask shaped
ulcers may have the neck occluded by debris or mucus
and may appear as yellowish nodules in the mucosa.

James thinks there is also a shallow surface ulcera-

76 PROTOZOAN PARASITISM

tion, with only minor tissue penetration by the
amoeba, but produced by their cytolytic substance.
Here there is superficial necrosis and sloughing, the
shallowness of the ulcer obscuring it from the casual
examiner.

Interestingly, Councilman and Lafleur (1891) de-
scribe a superficial mucosal necrosis and softening of
epithelium, along with the typical undermined ulcer
in amoebic dysentery, which they believed to be
produced by the cytolytic activity of amoebae on
the surface.

While such a state of the surface epithelium in the
acute form, amoebic dysentery, is consistent with
the state of the intestine, it is difficult to relate it
with a chronic condition. Further investigation will
be required to show that such surface lesions are
of amoebic origin and that they are a characteristic
state of the chronic phase of the disease.

It is somewhat difficult at the present to evaluate
the various findings and beliefs. It is, perhaps, sig-
nificant that some of the most experienced workers
who once believed that Endamoeba histolytica is an
obligatory tissue invader, that its presence in the
intestine always signified tissue destruction, have
changed their minds and are now convinced that the
organism may dwell only in the lumen at times.

All of which comes to the possibility that the
symptomless "carrier" state of intestinal amoebiasis,
possibly the condition of chronic intestinal amoebia-
sis, covers the large group of infections by Endamoeba

OF THE ALIMENTARY TRACT 77

histolytica, where the amoeba is mainly or solely,
as a common thing, a lumen dweller, occasionally be-
coming seated at the bottoms of gland crypts, where
it may produce necrosis and enter the tissues, possibly
destroying surface epithelium, as James observes,
without penetrating below that. Certainly for the
most part it must live and multiply in the lumen of
the bowel if its numbers and prevalence are what they
appear to be.

As a lumen dweller does it disturb the host? That
remains to be answered.

The whole question of the state of the host in
chronic intestinal amoebiasis and in the symptom-
less carrier of Endamoeha histolytica has yet to be
settled; whether the vague disturbances of intestinal
tract and of general health now attributed to this
low grade infection are related to it. James believes
that this state is exceedingly common, that it is of
more importance to the human race than any other
protozoal disease, even than malaria, that intestinal
amoebiasis presents a disease state as protean in its
manifestations as syphilis itself.

We have come, then, from the recent start of
knowing amoebic dysentery as the disease produced
by Endamoeha histolytica, to the point where this
is recognized as the uncommon acute or relatively
acute phase of the disease, w^hile there exists in the
population at large an incidence of latent infection
conservatively estimated at from 5 to 10%, in many,
if not all, of which it is the belief of careful and com-

78 PROTOZOAN PARASITISM

petent experienced men that there is a chronic low-
grade disease, of devitalizing quality but diagnosable
only on finding the amoeba.

There is much yet to be learned about intestinal
amoebiasis.

ACUTE AMOEBIC COLITIS (aMOEBIC DYSENTERY)

The acute phase of the disease has long been known
as tropical dysentery. Although much more common
in hot countries it is occasionally seen in other cli-
mates, in which it is more apt to occur in the summer.
That the climate is directly related has not been de-
termined. Certain tropical and subtropical countries
are more prolific of intestinal amoebiasis because of
hygienic conditions. Other conditions in hot coun-
tries are probably related to the production of these
acute attacks, the devitalizing heat and humidity,
possibly the food. Certain it is that intestinal amoe-
biasis in temperate or colder regions does not show
this phase as commonly, even relatively.

There seems to be no proof that there are strains
of the amoeba of different degrees of virulence, al-
though some experimentation may have so indicated.
In fact the work of Walker and Sellards (1913) is defi-
nite evidence against variations in virulence among
different strains.

The resistance of the host to the infection appears
to be of more concern, although as to just what is in-
volved in that resistance we have little knowledge.

OF THE ALIMENTARY TRACT

79

Fig. 14. — Acute Amoebic Colitis.

Large undermined ulcers with slougliing. (U. S. Army Medical
Museum No. 39,112. Also from Haughwout and Callender.)

80 PROTOZOAN PARASITISM

The characteristic pathology of the condition is
as described by Councihiian and Lafleur (1891), with
the undermining and tunnelling ulcer of the sub-
mucosa, distributed mainly in the caecum and as-
cending colon but not uncommonly involving the
whole large intestine and extending over the ileocae-
cal valve. Penetration of the wall with perforation,
peritonitis, extension into the meso-colon and re-
troperitoneal tissues, liver abscess, and rarely more
distant amoebic abscesses may occur during its
course.

As the condition becomes prolonged, healing of
ulcers and the formation of fibrous adhesions between
the intestinal coils and surrounding viscera may pro-
duce extensive matting of the abdominal viscera and
deformity of the intestine.

The "moth-eaten" appearance of the colon at
autopsy is typical and not to be confused with ulcera-
tive colitis of other origin.

Among the symptoms of the disease, dysentery,
with numerous blood-stained mucous stools, '' bloody
flux," is outstanding. It is reported that acute amoe-
bic colitis may occur without dysentery and the
characteristic stool, and I have done autopsies on
cases dead of the condition, in whom there was no in-
formation of diarrhoea or dysentery. It is not im-
probable that dysentery has existed in some persons,
the condition of whom at the time of observation
precluded the possibility of obtaining correct informa-
tion. Involvement of the rectum produces pam.

OF THE ALIMENTARY TRACT 81

tenesmus, frequent small stools of glairy mucus with
fresh blood, and straining at stool.

Disturbed digestion, tenderness over the intestine
on pressure and colicky abdominal pains are promi-
nent disturbances.

Systemic debilitation, loss of weight, weakness, vary
with the severity of the attack. As it is prolonged
they become prominent, and anemia, exhaustion and
emaciation may be pronounced in the severe or fatal
case.

Enlargement of the liver with or without sensitive-
ness varies in the experience of different observers.
Early amoebic hepatitis may give an enlarged sen-
sitive liver and a trace of jaundice.

Later amoebic liver abscess may produce a more
pronounced state of a similar kind, probably with
evening fever, chilly sensations or actual chills, and
blood leucocytosis.

Proctoscopic or sigmoidoscopic examination m.ay
or may not reveal ulcers of the examined intestine.
Negative findings here by no means exclude amoebic
colitis, since there may be extensive involvement of
the higher colon. Fever may or may not occur and
when there is a blood leucocytosis it is probably due to
a secondary bacterial infection.

An attack of amoebic dysentery may occur as the
first evidence of intestinal amoebiasis or it may occur
as an acute flare during the course of the chronic
disease ot as its end result.

In recovery from the acute attack there is gradual

82 PROTOZOAN PARASITISIM

convalescence, with decreasing symptoms, to the
point of a few mucous stools a day, with tenesmus,
disturbed digestion, anemia and emaciation, or merely
the state of ''neurasthenia" with indigestion, previ-
ously recited, in which constipation is prominent, or
to a state of symptomless and seeming good health.

A concise conception of the pathology of the dis-
ease suffices to explain the clinical state fairly com-
pletely. It also is of great importance to a clear
understanding of the reasonable expectations in the
practical treatment of the phases of intestinal amoe-
biasis.

THE STOOLS OF DYSENTERY

While the stool of amoebic dysentery is character-
istically of blood stained mucus there is a certain
amount of possible error in depending on this gross
appearance as a diagnostic feature. This has been
emphasized by Haughwout (1924), by Haughwout
and Callender (1925), and by Callender (1927), who
have called attention to the practical value in diag-
nostic procedure of a microscopic study of the stool
for other cells as well as for the organisms.

The writer (1917) called attention to the confusion
which might occur between large phagocytic cells
in acute non-amoebic dysentery (probably bacillary
dysentery) and amoebae.

In bacillary dysentery there will be in the stool,
which may be more or less blood stained and mucin-

OF THE ALIAIENTARY TRACT 83

ous, variable numbers of leucocytes, largely polynu-
clears, red blood corpuscles, and, particularly, large
phagocytic endothelioid cells. These macrophages
are practically non-motile as seen in the stool and
contain ingested cells or cell particles. Whole
leucocytes and red blood corpuscles or remnants of
these ingested cells may appear in these phagocytes.

Fig. 15. — Stool of Bacillary Dysentery.

Mononuclear phagocytes and leucocytes. (U. S. Army Medical
Museum No. 41,158. Also from Haughwout and Callender.)

All phases of degeneration and disintegration of these
cells as well as of leucocytes may be seen. The cel-
lular content of the stool of bacillary dysentery is con-
spicuous.

On the contrary the stool of uncomplicated amoebic
dysentery has few cells, possibly a few mononuclears
and an occasional polynuclear. The body of tissue

84 PROTOZOAN PARASITISM

origin which is conspicuous is the red blood corpus-
cle.

Uncomplicated amoebic dysentery does not pro-

FiG. 16. — Stool of Amoebic Dysentery.

Red blood corpuscles and an amoeba with partially digested
corpuscles. Photomicrograph x 1000.

duce the macrophage in the stool, while it is rather
characteristic of bacillary dysentery.

In cases of the latter naturally there may be an
amoebic infection. If there is an exudate as of bacil-
lary dysentery in a stool containing Endamoeha histo-

OF THE ALIMENTARY TRACT 85

lytica the indications of the bacillary dysentery are,
of course, of the more immediate importance. The
amoebic infection may be attended to when the bac-
terial infection is overcome or shown to not exist.

It is in such a stool that the active form of End-
amoeba coli is most apt to be mistakenly identified
as Endamoeba histolytica and the whole case mis-
judged.

When pus and these large phagocytic cells are
features of the stool examination, utmost care should
be exercised to avoid overlooking the occurrence of
bacillary dysentery, particularly when an amoeba is
present to confuse, and more especially when it is
thought to be Endamoeba histolytica.

These are recommended as important practical
considerations.

TREATMENT

In the opinions of practitioners of wide experience
wdth the disease those w^ho expect cure of intestinal
amoebiasis or eradication of the amoeba from the
intestine by any brief course of medication will come
to disillusionment if they follow the course of their
bona fide cases carefully and truthfully.

The first requisite to proper handling of a case
of the disease is a correct diagnosis.

Since the dysfunctions of amoebic dysentery and
chronic intestinal amoebiasis not uncommonly dis-
appear spontaneously or without specific treatment

86 PROTOZOAN PARASITISM

one must be guarded in speaking of bringing about a
cure by any measure merely on the evidence of a
return of the patient to apparently normal health.
One may assist in relieving the disturbance of the
disease but to cure intestinal amoebiasis necessitates
the eradication of the amoeba from the host. With-
out ascertaining conclusively that this is the case one
should not speak of a cure. This can be determined
only by examining for the amoeba over a fairly
lengthy period, bearing in mind that its numbers
naturally vary and that after any ordinary thera-
peutic attack, especially if there has been recovery
from the clinical state of amoebic dysentery, it may
be very sparse for some time.

Absence of the amoeba from the stool by repeated
careful examination, such as has been previously
detailed, for a month or longer may be taken as rea-
sonable proof of the eradication of the parasite.

The drug of longest specific use in the treatment
of intestinal amoebiasis is ipecac. While ipecac
itself is still used by some it has been largely replaced
by its alkaloid emetine. This drug, although lethal
to Endamoeba histolytica only when as strong as 1
to 10,000, according to Kofoid and Wagener (1925),
exerts a powerful specific effect on the amoeba in the
tissues of its host, it being particularly valuable in
the active phases of the disease, usually controlling
amoebic dysentery promptly. It is less effective
against the ''carrier" or the host who does not exhibit
signs of tissue invasion. In that case a more power-

OF THE ALIMENTARY TRACT 87

ful amoebicicle is necessary, referring probably to the
difference in location of the amoebae. The action of
emetine appears to be rather indirect than direct on
the amoeba.

The manner of administering the drug varies and
this undoubtedly effects the success attending it.
Emetine may be given hypodermically or orally or
by both avenues simultaneously.

Dobell's (1921) method of giving emetine bis-
muthous iodide (double iodide of emetine and bis-
muth) is as follows:

Emetine bismuthous iodide is an insoluble brick
red powder. It should be obtained from a trust-
worthy source and be guaranteed to contain not less
than 26% of the alkaloid. The dose should be three
grains daily, by mouth, for twelve consecutive days,
not less. This may be attended by some nausea, but
this can usually be controlled by a small dose of tinc-
ture of opium previously and by giving the drug af-
ter going to bed at night and not on an empty stomach.
Dobell believes that this course will usually remove
an infection with Endamoeha histolytica perma-
nently, without giving symptoms of emetine poison-
ing. When it does not rid of the amoeba a further
course should be given, three grains daily for twenty-
four consecutive days or an ordinary twelve day
course supplemented by emetine hydrochloride (%
to 1 gr. daily) hypodermically at the same time.

Wenyon and O'Connor (1917) advocate the com-
bined oral and hypodermic administrations of eme-

88 PROTOZOAN PARASITISM

tine hydrochloride. One grain of the alkaloid is
given hypodermically in the morning and one-half
grain in a keratin coated tablet at night by mouth,
both every day for twelve consecutive days. James
and Decks (1924) recommend the use of emetine hy-
podermically with concurrent administration of bis-
muth by mouth. A routine in active amoebic colitis
is as follows :

Give a preliminary dose of castor oil. Put the
patient to bed and limit the diet to liquids, prefera-
bly milk. If tenesmus and griping pains are severe
give a hypodermic of morphine and atrophine as in-
dicated. Emetine hydrochloride hypodermically in
1/2 grain doses twice daily or 1 grain doses daily for
9 to 10 days. Bismuth subnitrate, a heaping tea-
spoonful (180-200 grs.) is mechanically mixed in a
glass of water and taken every 3 to 4 hours. When
the stools begin to form the bismuth is decreased to
three times daily and a generous diet is gradually in-
stituted.

Rectal irrigations of quinine, silver salts, iodine
and other agents are unnecessary, according to Decks,
as are surgical measures for irrigating purposes.

These courses of treatment for active cases of
amoebiasis take into account the stubborn nature of
the infection and, particularly that of James and
Decks, the pathologic state of the intestine. It is not
to be expected that the intestinal ulcers are to be
healed in the periods of time covered by these thera-
peutic courses. One has only to picture the condition

OF THE ALIMENTARY TRACT 89

to appreciate that. Consequently general measures
aimed at allowing the best conditions for recovery of
the intestine should be well borne in mind. For this
purpose, apparently, is the use of bismuth. Such a
diseased person should be governed by much the same
rules as in any comparable ulcerative state of the
bow^el. Confinement to bed during the active phase
of the disease and consistent with the physical state
during convalescence is of importance.

The diet is probably of more consequence than one
may now conclusively state, in fact there are indica-
tions that the diet may be an important factor in the
aggressiveness of the amoeba. A bland liquid diet
during an acute attack (Deeks specifies milk) and well
balanced, nutritious, but not heavy feeding of non-
irritating foods during the treatment of any form of
the condition should be attended to. A reduction of
the carbohydrates of the diet, sufficient protein, par-
ticular attention to green vegetables and fresh fruits,
are to be recommended.

At the risk of being burdensome the writer w^ould
re-emphasize to practitioners that treatment is of
both specific and non-specific kinds. The specific
drugs must be given in sufficient dosage or long
enough to kill out the amoeba. The non-specific
is such as one would use for any similar pathologic
state, remembering the nature, extent and loca-
tion and the time required for the healing of such
lesions.^

Of the newer measures of treatment, that out-

90 PROTOZOAN PARASITISM

lined by Cort (1928) emphasizes the present day
idea that emetine is not to be depended upon to elim-
inate the amoebic infection but is most valuable in
controlling the active phase of the disease. He rec-
ommends emetine in 1 grain dosage intra-muscularly
daily for 7 days. After an interval of 1 week another
series of 5 injections are given; then 2 series of 2 to 3
injections at intervals of 1 month. With frequent
stools or loss of sphincter control, use chiniofon
(yatren) enemas, one a day, with bismuth or opium,
as indicated.

When the stools are less frequent give acetarsone
(stovarsol) by mouth, (as well as emetine) one 4
grain tablet twice a day for not more than 6 or 7 days.
Then continue with chiniofon (yatren) pills, first
two 4 grain tablets twice daily, increasing to four pills
three times a day. Repeat this course at the end
of one month.

Cort considers emetine a specific for amoebic hepa-
titis but not for intestinal amoebiasis, which inter-
preted appears to mean that the effect of the amoebic
products, from the ulcers of the intestine, upon the
liver is counteracted in some way by the drug, that
again the influence of emetine is more on the host
than the parasite.

In Cort's experience abscesses of the liver should
be aspirated and then treated with emetine, while in
case of poor surgical risk on account of the amoebia-
sis, emetine may convert into a state favorable to
operation.

OF THE ALIMENTARY TRACT 91

In active phases of the disease when the patient
is in bed or may be so confined, chiniofon (yatren)
may be an effective drug, given in cachets of 3 grams
per day for 10 consecutive days, accompanied by a
liquid diet. It may also be used by rectum. It may
produce diarrhoea itself.

In the experience of Jones and Turner (1929)
yatren is a valuable drug in intestinal amoebiasis,
particularly in dysentery, given in pills of 0.25 gms.
each, coated, with phenyl saUcylate, 1 gram by mouth
three times daily during the first and third week,
none in the second. No restriction of diet or con-
finement to bed is necessary. Children may be given
a proportionate dose. There were no toxic manifes-
tations but the drug may cause diarrhoea. The
eft'ect is claimed to be directly upon the amoeba in
the intestine, and ulcers of the rectum healed in from
seven to fourteen days.

Decks (1928) reaffirms the excellence of his treat-
ment with bismuth and emetine in amoebic dysen-
tery, and says that the newer measures of treatment
by bismuth-emetine-iodide, yatren, and stovarsol
have not given equally good results.

Another valuable drug of comparatively recent
introduction in the therapeutic armamentarium
against amoebiasis is acetarsone (stovarsol), an ar-
senical preparation. Several arsenical drugs appear
to be amoebicidal in much higher dilution than other
so-called specifics for amoebiasis. According to Kof-
oid and Wagener (1925) the lethal dilution of stovar-

92 PROTOZOAN PARASITISM

sol is 1 to 95,142, of neo-arsphenamine 1 to 142,000,
of arsphenamine 1 to 100,000.

Stovarsol has the miportant advantage of being
effective by mouth administration and without the
necessity of putting the subject of treatment to bed.
While it is of value in the acute case, it is of particu-
lar application to the ambulatory chronic case and
the healthy carrier, according to Craig (1928).
Symptoms of arsenic intoxication were obtained by
giving one tablet (0.25 gm.) three times daily for a
week, these consisting of gaseous abdominal disten-
tion, colickly pains, mild diarrhoea, and erythema.
One-half tablet given three times a day for one week,
with a cessation of treatment for one week, and a
repetition of the course for the third week gave no
untoward effects, and eliminated the amoeba in the
majority of cases treated. Those not completely re-
lieved by this course were so benefited by a second
similar treatment. The subjects may be allowed to
continue their occupations with dietary restrictions
of rich foods and excessive carbohydrates.

In the consideration of all of which, the presen-
tation of the several so-called "specifics" and the
different measures of administration, lies the
acknowledgment that the treatment of intestinal
amoebiasis has yet to be proven as satisfactory as
some have claimed.

Sometimes one measure and then another gives
brilliant results, sometimes apparently none.

It must not be forgotten that the drugs are not

OF THE ALIMENTARY TRACT 93

harmless themselves and that the course of treatment
must be watched.

Finally, for re-emphasizing, the nature of the or-
ganism, its two phases, its habitat, in the lumen, in
ulcers, in tissues, the local destruction of tissue and
the necessity for producing healing, the possible ex-
tra-intestinal involvement, all must be considered in
any rational medical attack upon the obviously dis-
eased host or the apparently healthy carrier. Time
and care are no small parts of the treatment.

CHAPTER V

The Amoebae (Continued)

Endamoeha coli. Morphology. Prevalence and Im-
portance. Habitat and Effects. Court cihnania lafleuri.

ENDAMOEBA COLI

The most common amoeba of the intestine of man,
Endamoeba coli, was, according to Dobell and O'Con-
nor (1921), first studied by Lewis (1870) and Cmi-
ningham (1871) in India. It is in prevalence, num-
bers, and size, the most prominent of this class of
parasites.

MORPHOLOGY

The active form may vary from ten to forty microns
in diameter but is usually between twenty and thirty.
In the actively motile condition, taken fresh and
warm from the contents of the higher large intestine,
it is usually much less energetic than Endamoeba
histolytica, moving about more slowly, not in such a
'^streaming" manner, and its pseudopodia are less
prominent, less clear and not so ''explosive." The
ectoplasm and endoplasm are not so well divided and
there may be but little difference except in the pseudo-

94

OF THE ALIMENTARY TRACT 95

podia. However, it is not uncommonly seen, in favor-
able specimens of stool or in culture material, when
these differences from Endarnoeba histolytica are in-
conspicuous and when it defies positive identification
by experienced observers. It is this fact which fre-

.!.'S .

'r6r_: ■©,-

K4 ?

^^^^^•- ^

•:^^*-v^

«

Fig. 17. — Endamoeba coli.

Drawings of trophozoite and cysts with one, two, four and eight
nuclei, from specimens stained by iron-haematoxylon. x 1000.

quently produces an erroneous diagnosis of intestinal
amoebiasis in the practice of medicine.

The nucleus of this amoeba, as distinguished from
Endamoeba histolytica, is usually visible in the fresh
unstained living and moving organism. It is seen
as a round ring, not a vacuole, in the more granular
and vacuolated endoplasm. It flows about during

96 PROTOZOAN PARASITISM

the progressive motility of the amoeba in a passive
way, along with the other inner contents. It is best
seen as the amoeba changes its position, when there
is protruded a long pseudopod into which flows the
endoplasm. As the nucleus moves into the forward
pseudopod it may be plainly seen.

The endoplasm in this phase is usually grossly
vacuolated and contains numerous food bodies of a
variety, bacteria, yeasts, Blastocystis, crystals, and
even the cysts of other protozoa. These objects give
evidence of its natural food supplies. In contrast,
Endamoeba histolytica seldom contains bacteria and
probably never consumes these other objects com-
monly seen in E. colL As a rule Endamoeba coli
does not eat red blood corpuscles ; in fact it seldom has
the opportunity, but it may apparently do so under
certain conditions. The writer (1924) incubated at
37.5°C. portions of fresh stool containing large num-
bers of sluggish amoebae in test tubes containing
0.9% sodium chloride solution to which was added a
small amount of fresh human blood. Within two
hours the amoebae became very active in motility and
had ingested many red blood corpuscles. Subse-
quent repeated examination of the stools of this per-
son never revealed any but an eight nucleated
amoeba cyst, identified as E. coli. The only question
arising about the identification of the amoeba of this
experiment is raised by Kofoid and Swezy's (1921)
description of a new genus, Councilviania, the species
of the human intestine named Councilviania lafleuri,

OF THE ALIMENTARY TRACT 97

which as yet has not been well accepted by protozoolo-
gists and which must be held sub judice. These in-
vestigators use the phenomenon of phagocyting red
blood corpuscles as one of the main features of differ-
entiating the active forms of Endamoeha coli and
their Councihnania lafleuri. The particular features
of difference between the two as specified by them are
the "dispersed" karyosome of Councihnania as con-
trasted to the compact form of that of E. coli, and the
reproduction by budding from the cyst of the former.
The dispersed karyosome was present in some of the
cysts of the amoeba encountered in this experiment
but the process of budding was not seen at any time.
Should Kofoid's contention be accepted this experi-
ment will no doubt be considered to affect Council-
mania lafleuri and not Endamoeha coli.

Dobell and O'Connor (1921) say of Endamoeha
coli, that the food "vacuoles never contain red blood
corpuscles," while Wenyon and O'Connor (1919)
state, "If amoebae containing red blood corpuscles are
present in the stool — they are Eiidamoeha histo-
lytica." This long accepted feature of difference be-
tween E. coli and E. histolytica must be held subject
to question as a positive means of differentiation for
the present.

When the amoeba is obtained from the lower colon
or in the ordinary stool it is proceeding to encystment
or is already encysted. The "precystic" form is
smaller, it has stopped feeding, it is sluggish or mo-
tionless. If it shows pseudopodia they are small, its

98 PROTOZOAN PARASITISM

eiidoplasm is granular, and there is no sharp delinea-
tion of ectoplasm. In this small sluggish precystic
form it is not safe to attempt differentiation from E.
histolytica in unstained specimens, nor probably in
stained preparations except in expert hands.

The cyst is the form to be positively identified by
any who can find these bodies and can count the nu-
clei in unstained or stained preparations. The
cysts usually show in characteristic appearance in
formed stools, measuring from ten to thirty or more
microns in diameter but usually between fifteen and
twenty. They are larger than cysts of E. histolytica
as a rule. They are rounded, have a rather thick
wall, the body is finely granular or hyaline in the liv-
ing cyst and they have typically eight nuclei. Chro-
matoid bodies are not conspicuous in the mature cyst.
They appear as splinters or slivers or filamentous
lines. Sixteen nuclei, or even thirty-two, may be
seen. In the immature cysts glycogen is prominent,
especially in the iodine preparation, the nuclei are
larger and the chromatin more prominent, the chro-
matoid bodies are more common and more numerous,
and the nuclei are one, two, or four in number. The
writer (1924) has observed Endamoeha coll (unless
it be Councilniania) which showed constantly a chro-
matoid body of round form about the size of the ma-
ture nucleus, in the cyst.

The nucleus hi E. coli is characteristic and may
usually be seen in the living organism at any stage.
In the very active streamingly motile form it may be

OF THE ALIMENTARY TRACT 99

invisible. It is seen unstained as a refractive ring
of granules, and the number of nuclei may be com-
monly counted in the living cyst. This, however, is
facilitated by the iodine preparation previously de-
scribed. The particularly important and practically
useful point about the cyst is that any amoeba in the
stool developing a cyst with more than four nuclei
is not Endamoeha histolytica. Let medical labora-
torians adhere to this point as an anchor.

Stained by the iron-haematoxylon procedure the
nucleus of both active and encysted forms is round,
has a definite rim, to which rather large chromatin
particles cling in irregular distribution. The karyo-
some is large and not in the center, although it may
appear so when the cyst is viewed in a certain expo-
sure. It is eccentrically situated. This body is com-
pact, although, unless Councilmania is valid, it may
appear as a group of small granules, and it is sur-
rounded by a ''halo." The nuclear network shows a
few granules of chromatin to the expert examiner.

It may, therefore, be readily seen that to the ex-
perienced there are morphological differences between
the nuclei of Endamoeha coli and Endamoeha histo-
lytica upon w^hich positive differentiation may be
made. To the inexperienced observer these features
are not so clear and unless they are they furnish no
help in diagnosis.

In iron-haematoxylon stained specimens the tro-
phozoite is seen beautifully prepared for observation
of it parts and ingested food.

100 PROTOZOAN PARASITISM

PREVALENCE AND IMPORTANCE

Endamoeha coli is by far the most common intes-
tinal protozoon. A large per cent of the population
of any place, if not the majority, will show it on thor-
ough search. It is an indication of the commonness
with which the food of man is contaminated with the
excreta of his fellow^s. Some believe that virtually
everyone harbors this amoeba at some time.

Whether it may spontaneously disappear from the
intestine is unknown. The writer know^s of one per-
son who has show^n it on numerous examinations over
a period of fifteen years.

Its particular importance lies in the common con-
fusion of it in medical practice with Endamoeha histo-
lytica. The writer knows of a number of instances
in which physicians have treated and ^^cured" cases
of intestinal amoebiasis or amoebic dysentery, so
diagnosed, in whom Endamoeha coli was the only
amoeba present and in whom it remained after the

HABITAT AND EFFECT

Endamoeha coli inhabits the lumen of the first
part of the colon in its actively feeding stage. As it
passes down the colon it encysts and passes out in
the feces, from which it is transferred to a new host
by ways previously discussed in the case of Endam-
oeha histolytica. In the intestine of its new host
it is liberated from the cyst and completes its division

OF THE ALIMENTARY TRACT 101

into eight offspring, from which point the life habits
and cycle are repeated.

It has never been known to invade the tissues or
to do anything harmful to its host. Other animals
may harbor amoebae of similar characteristics but,
so far as is known, they are distinct.

EXPERIMENTAL INFORMATION

Growth of Endamoeba coli in culture has been re-
ported by Kofoid and Allen (1926) and by St. John
(1926).

COUNCILMANIA LAFLEURI

To Kofoid and Swezy (1921) are due the credit for
either discovering a new genus of amoebae, parasitic
in the intestine of man and other animals, or of in-
troducing another element of confusion into an al-
ready complicated situation. In the status of this
question at the present time it is largely Kofoid and
his co-workers against the field of other protozoolo-
gists. The time is not yet when the controversy may
be settled or when one who has not been a material
worker on this particular question should bear any
but an open mind. Neither is this the place to an-
alyze the data in detail. The question is an im-
portant one in medical protozoology because of the
suspicion that Councilmania lafleuri may be harm-
ful to its host. It is considered sufficient to state
the problem at this time and to refer those who may

102

PROTOZOAN PARASITISM

be interested in the details to the reports of the
California investigators and of those who deny the
correctness of their observation.*

Councilmania lafleuri, the species of the intestine
of man, is described as being of an activity in mo-

FiG. l^.—Councilmania lafleuri.

As shown by Kofoid and Swez3^ A, trophozoite. B, budding
cyst. C, cyst. (Univ. of California Press.)

tion comparable to Endavioeha histolytica and as
readily ingesting red blood corpuscles. The wall of
the cyst is very thick and the shape of this body is

* See: Kofoid, C. A., and Swezy, O., Univ. of Cal. Publ. ZooL,
20, 169, 1921. Kofoid, C. A., Swezy, O., and Kessel, J. F., Ibid., 20,
431, 1923. Kofoid, C. A., Swezy, 6., and Kessel, J. F., Ibid.. 26, 21,
1924. Kofoid. C. A., and Swezy, O., Journ. Parasit. 10. 153, 1924.
Kofoid. C. A., Proc. Soc. Exp. 'Biol, and Med., 23, 299, 1926. Al-
len, E. A., Univ. of Cal. Publ. ZooL, 29, 175, 1926. Wenyon, C.
M., On Three Supposed New Entamocbae of Man. Trop. Dis.
Bull., 19, 19, 1922. Gunn, H., Councilmania lafleuri not a new
amoeba. Journ. Parasit., 9., 24, 1922. Wight, T., Notes on Coun-
cilmania lafleuri, Proc. Soc. Exp. Biol, and Med., 22. 517, 1925.
Wight, T. and Prince. L. H., Artifacts in Endamoebae which have
led to the Naming of a New Genus and Species. Am. Journ.
Trop. Med., 7, 287, 1927. Wenyon, C. M., Protozoology. Vol. I.
New York, 1926.

OF THE ALIMENTARY TRACT 103

not as definitely rounded but of the same general
appearance as E. coli. The nucleus has a thin layer
of peripheral chromatin and the karyosome is ''dis-
persed" instead of compact. The particular char-
acteristics upon which it seems that the validity of
the genus must rest are : ( 1 ) the reproduction by bud-
ding from the cyst of eight offspring through a pore
on a chromaphile ridge, and (2) the number of chro-
mosomes, said to be eight as contrasted to six in E.
coli.

Gunn (1922), Wenyon (1922), Wight and Prince
(1926), and others have denied the existence of the
process of budding, they having observed similar
processes occurring from cysts of E. coli as artifacts,
from pressure or other physical deformations, and at
least Wenyon (1926) questions the possibility of con-
sistent reliable counting of chromosomes in the divid-
ing nucleus of amoebae.

Kofoid and his co-workers continue to adhere to
the specific points which they have reported. They
have also reported cultivation of C. lafleuri, in which
it remained distinct from E. coli, encystment in cul-
ture (Allen, 1926), the occurrence of species of
Councihnania in rodents (1923), the observation of
cysts of C. lafleuri in duodenal drainage, the occur-
rence of two additional species in the human intes-
tine ( 1928), and an incidence of 7.8% in 4763 persons
on 20,264 examinations (1924).

The writer (1924), as previously recited, reported
upon an intestinal amoeba which had the character-

104 PROTOZOAN PARASITISM

istics of Councihnania, except that no budding was
seen, nor were chromosomes counted, which ingested
red blood corpuscles in culture tube.

Artifacts of the cysts of amoebae are certainly very
common, although nothing resembling budding of
amoebulae is often seen. The general characteristics
of the species are common in amoebae identified as
Endamoeha coll at the present. As far as the num-
ber of chromosomes is concerned, Wenyon's difficulty
is no exception. The burden of proof still rests with
Kofoid and his adherents but if the budding process
was correctly observed it will undoubtedly be only
a matter of time until the controversy is cleared.
Further, if the number of chromosomes in the divid-
ing nucleus may be accurately counted, and, of course,
they will be, this will be a point of mathematical
calculation not subject to personal equation. That
time is not yet, however, certainly not for the average
experienced observer. The number of chromosomes
in the nucleus of amoebae, identified as such by Kof-
oid, in the lymph nodes of Hodgkin's disease and in
the bones of arthritis deformans, has been used as
the main point of identification of Endamoeha histo-
lytica in these instances. It is a very important
point of cytological distinction and further work will
be of great interest.

CHAPTER VI

The Amoebae (Continued)

Endamoeha gingivalis. History and Relation to Pyor-
rhoea Alveolaris. ^Morphology. Habitat and Effects.
Experimental Information. Prevention and Treatment.

ENDAMOEBA GINGIVALIS

The common amoeba of the human mouth is E^id-
amoeha gingivalis, discovered by Gros (1849) as the
first known parasitic amoeba of man. Since that
time is has been rediscovered several times ; by Stein-
berg (1862), by Grassi (1879), by Prowazek (1904),
and by others. It has naturally been given several
names by its discoverers, among which Amoeba
dentalis and Entamoeba buccalis are still used, al-
though erroneously, at times.

At least as early as 1913 Professor Allen J. Smith of
the University of Pennsylvania w^as mterested in the
relation of this amoeba to pyorrhoea alveolaris and
was working on the problem. Associated with him
was Dr. M. T. Barrett, a dental practitioner. He
later had associated with him in the study of E.
gingivalis in the tonsils Dr. W. S. Middleton. In
1914 Barrett published a preliminary account of this

105

106 PROTOZOAN PARASITISM

work, in which the positive occurrence of E. gingivaUs
in forty-two cases of pyorrhoea and the absence of it
in normal mouths was reported. This report of
Smith and Barrett states a belief in the pathogenicity
of the amoeba on account of its constant association
with the disease, its absence from normal gums, its
tissue cell inclusions, and the elimination of the
amoeba and improvement of the disease by treatment
with emetine.

Chiavaro (1914) published a report immediately
following this, in which he ascribed no etiological role
to the amoeba which he observed in twenty-two cases
of pyorrhoea and a few out of a number of cases of
dental caries.

Also in 1914, Bass and Johns recorded the presence
of E. gingivaUs in pyorrhoea in eighty-two cases.
These investigators (1915A and 191oB) later pub-
lished a report of three hundred cases of pyorrhoea
harboring the amoeba and also a book presenting their
observations and ideas on the subject. They were
convinced of the etiological relation of the amoeba
to pyorrhoea alveolaris and of the relief to the infec-
tion and the progress of the disease attending treat-
ment with emetine.

Further investigation by Smith, Middleton and
Barrett (1914), by Smith and Barrett (1915) and by
Evans and Middleton (1915) enlarged the field to in-
clude consideration of the presence of E. gingivaUs
in the tonsils, and the suggested relationship of
systemic complications such as arthritis and anaemia.

OF THE ALIMENTARY TRACT 107

Spectacularly hopeful as was the rise of oral amoe-
biasis, especially in relation to common pyorrhoea
alveolaris, its downfall was equally but disappoint-
ingly rapid and spectacular. Following the reports
of the Philadelphia and New Orleans investigators the
dental and medical professions, in common parlance,
took ''hook, line and sinker." Emetine and alcresta
ipecac w^re to eradicate pyorrhoea, hitherto and now
either most difficult or unmanageable, and the specu-
lated effects upon systemic states of disease w^ere
many. At the present time, the theory of oral amoe-
biasis and its cure by specific treatment is prac-
tically totally discounted.

The writer (1915), while not doubting that E. gin-
givalis was related etiologically to pyorrhoea, reported
its presence where it was obliged to be a harmless
dweller, and also in ulcers of the mouth and tongue
where it was probably only a contaminant. It was
also recorded that the ipecac treatments so enthusi-
astically recommended at the time had failed to
eliminate the amoebae from some pus pockets and
to bring about a cure of cases of pyorrhoea. A warn-
ing was sounded as to the constant pathogenic
relationship of the amoeba, the necessity of consider-
ing other factors, and the unsoundness of expectancy
of ^'cure" in certain cases of Rigg's disease.

Under the conditions of the occasion a bona fide
specific cause and treatment would have suffered a
reaction; perhaps similar to that which occurred.
There was so much "chaff" in general dental and

108 PROTOZOAN PARASITISM

medical practice that if there was any good at all it
became hopelessly lost. Soon began to appear ad-
verse reports as to the relation of the amoeba to
pyorrhoea and the failure of the suggested treatment
and it was not long before the whole idea was gener-
ally abandoned.

It would seem remarkable indeed that those who
were instrumental in the rise of oral "endamoebiasis"
should have been so completely in error in their ob-
servations. It is difficult for the writer to believe
that some of what he saw in this work was unreal.
It is suggested — with timidity — that the canons of
oral amoebiasis have not been closed, that somewhere
in this work was something real which will yet be
uncovered from the avalanche of reactionary report.

THE AMOEBA

The amoeba of the mouth, which may be found
in fresh preparations in the living and moving state^
and whose structure may be studied in detail by the
iron-haematoxylon staining method previously out-
lined, is most easily found in thin smears stained
as an ordinary blood film, by Wright's or Leishman's
stains. In the fresh warm motile state it reminds one
of Etidamoeba histolytica, having a similar progres-
sive motility. Ordinarily it ranges from ten to
twenty-five microns in diameter. In fresh prepara-
tions it may be seen to emerge from the particles of
debris with which it is in intimate association and

OF THE ALIMENTARY TRACT

109

to move across a clear field in rapid progression. Its
ectoplasm is clear and hyaline, its pseudopodia hya-
line, broad, and frequently thrust out in a sudden
manner. The endoplasm is granular and food par-
ticles may usually be seen in it. The nucleus is
usually not to be seen in such specimens.

Stained with the blood film stains the amoeba is

Fig. 19. — ■Endamoeba gingivalis.
Drawings of specimens stained by iron-haematoxylon. x 1200.

conspicuous. The ectoplasm and pseudopodia are
deep blue, the endoplasm is lighter blue and contains
purplish nuclear particles of ingested body cells and
possibly pink erythrocytes or remnants. While the
nuclear detail is not brought out in such preparations
it may be seen as a red body. Variously stained
bacteria occur in vacuoles in the endoplasm.

The nucleus is best studied in iron-haematoxylon
preparations, which also reveal the parts and ingested
objects of the parasite. The nucleus is rounded, there

110 PROTOZOAN PARASITISM

are irregularly distributed chromatin granules on
the rim and a central or near-central karyosome.

For the finer details of morphology the reader is
referred to Kofoid and Swezy (1924).

The existence of cysts has not been conclusively
shown. It is not unlikely that the conditions of its
environment, in which there is no comparable regular
change and inspissation of its medium, such as is
associated with intestinal amoebae and related to
their encystment, and, also, the literally direct ready
transmission from one host to another, have made it
unnecessary that this protozoon should have such a
resistant protection. If it ever encysts it must be
under rare and unknown conditions.

HABITAT AND EFFECT

Endamoeha gingivaUs is practically a universal
inhabitant of the mouth of man at some time during
an average lifetime. All people who have any degree
of pyorrhoea alveolaris harbor it, and most people past
early adult life have some grade of this condition.

It ma}^ be found in the crypts of the tonsils, in
ulcers of buccal mucosa or the tongue. Generally
speaking it does not occur in the normal mouth but
it may and commonly does occur whenever there is
a recess or pocket in which it may grow and accumu-
late. The writer (1915) recorded findhig it on the
false teeth and between them and the gum of two
persons who were completely toothless, with healed

OF THE ALIMENTARY TRACT 111

gums and alveolar processes. In ulcers of buccal
mucosa and tongue, where it was observed (Lynch,
1915), its appearance and disappearance seemed to
bear no relation to the development or progress of the
pathological state. It was evidently a secondary
invader there.

The amoebae may be found in any grade of in-
flammation of the gums, from that grossly incon-
spicuous but showing a tendency of the gingiva to
bleed unduly and microscopic pus behind the margins,
to the chronic suppurative inflammation wath pus
pocket formation and receding of the gum margins,
known as pyorrhoea alveolaris, in all of its stages of
advancement. It occurs where there is exudation
from inflamed tissue and a harbor for its lodgment.

In the depths of the pus pockets it flourishes,
as was shown by the writer ( 1915) , by Bass and Johns
(1915), and more recently by Kofoid and Hinshaw
(1929), who, according to Kofoid (1929), studied the
amoeba in relation to its w^hole environment by sec-
tion of the pus pocket and surrounding structures in
toto. According to these investigators the amoebae
occur about the filamentous border of leptothrix and
other similar bacteria which have undergone calcifica-
tion to form the tartar. Here they feed on the nuclei
of the disintegrating pus cells. They are very nu-
merous and form a heavy layer in the outer free fila-
mentous covering of the solid serumal tartar, being
most abundant about the point in the deeper part of
the pocket where the tartar is thickest, and extending

112 PROTOZOAN PARASITISM

some distance below the tartar adjacent to the
cementum. They do not invade the gingival or bony
tissues but the latter between the teeth and below
the level of tartar formation is extensively absorbed.
This report expresses the observation of the present
writer in failing to find invasion of the tissues by
the amoeba.

Kofoid (1929) develops a very pretty chain of
argument from his studies, leading to the inference
of a part in the events of pyorrhoea alveolaris played
by Endmnoeha gingivalis. In the first place is the in-
fection by leptothrix and other filamentous bacteria,
as a basis for the tartar formation by their calcifica-
tion. Next comes the amoebic infection which is
able to maintain itself on the fringes of the tartar
calculus. There the amoebae consume leucocytic
nuclei and excrete from these nucleo-proteins, phos-
phorous, available for deposit in the tartar as calcium
phosphate. The bone of the adjacent teeth is re-
sorbed near the site of the deposit of the calcium
carbonate and phosphate by some unknown process.
Thus one is led to suspect the triad, bacteria,
amoebae, calculus, against which the more successful
dental measures of instrumentation and surgery in
the treatment of pyorrhoea may be directed, although
unconsciously.

The amoeba not only ingests nuclear remnants of
pus cells but it may consume red blood corpuscles
(Smith and Barrett, 1915, and Howitt, 1925) and may
even haemolyze these elements without ingesting

OF THE ALIMENTARY TRACT 113

them. When erythrocytes are ingested they are
rapidly destroyed, thus apparently accounting for
the fact that they are rarely recognized in the
amoebae.

Ohira and Noguchi (1917) probably first cultivated
Endainoeha gingivalis, in a medium of ascitic fluid
and Ringer's solution in equal parts. If so, this was
the first successful cultivation of a parasitic amoeba.
It has been extensively cultivated by Drbohlav
(1925), by Howitt (1925), and by Dobell (1926), a
favorable medium for its growth being the L. E. A.
preparation of Boeck and Drbohlav (1924) as modi-
fied by Drbohlav, described in the cultivation of Eiid-
amoeba histolytica. Howitt recommends the use of
0.25 grams of glucose instead of 2.5 grams, as origi-
nally given, in making up Locke's solution.

In culture Howitt (1926) found that emetine in
dilution of 1 to 25,000 diminished but did not elim-
inate the amoebae and a few were alive in dilution of
1 to 1660. Stovarsol was the most effective amoebi-
cidal agent used.

Koch (1926) found acriflavine in dilution of 1 to
200,000, acridine yellow R 1 to 90,000, and aurimine,
diluted 1 to 60,000, lethal to the amoebae. These
dyes were not injurious to the gums of rabbits and
it was suggested that they might be used in the hu-
man mouth. Koch (1927) also found the amoeba to
be resistant to lower temperatures than that of the
body, while it could be killed by a temperature of
55 °C. in two minutes, by 52 °C. in ten minutes, and

114 PROTOZOAN PARASITISM

by 45 °C. in twenty minutes. The organism could
withstand apparent drying for about three minutes,
showing the possibility of droplet transmission.

Kofoid (1929) reports that in his laboratory dogs
have been successfully infected experimentally with
Endamoeha gingivalis. Of these animals only those
with gingival inflammation, pocket formation or
loose gingivae at the time of inoculation, were sus-
ceptible. He found all of the monkeys which he ex-
amined to harbor an amoeba indistinguishable from
E. gingivalis, those having the heaviest infections
showing a condition closely resembling pyorrhoea in
man. It should be noted that Goodrich and Moseley
(1916) found an organism indistinguishable from E.
gingivalis in the mouths of dogs having a similar
condition to pyorrhoea in man. The writer has been
unsuccessful in attempts to plant the amoeba from
the human mouth directly to the gums of guinea
pigs, rabbits, and dogs, all animals used having ap-
parently normal gums and teeth.

PREVENTION AND TREATMENT

At the present time the treatment of oral amoebia-
sis cannot be very intelligently discussed. Man is
universally subject to the infection very commonly.
It is undoubtedly transmitted from person to per-
son by direct or almost direct mouth passage, proba-
bly in large part by the act of kissing. Were it de-
sirable to prevent this infection avoidance of such
direct contact might be very effective. Indirect pas-
sage by means of the cup, spoon, fork, or other like

OF THE ALIMENTARY TRACT 115

used object, contaminated by an infected person
and on which the amoebae had not been killed by
complete drying, may be a factor in its spread. The
immersion of such objects in water at o5-60°C. or
above for a few minutes would render them amoeba
free.

Of mouth washes, that of emetine would seem
necessarily ineffective. Those desiring such a solu-
tion of apparently amoebicidal properties should try
stovarsol or such of the dyes used by Koch as may be
conveniently used in such a manner. Anyone who
expects to eliminate an established infection by means
of mouth washes will be disappointed.

As to any further specific treatment of pyorrhoea,
the writer hesitates to make such a recommendation
except as an experimental measure. In the heyday
of treatment with emetine, suppurative disease of
the gums with small pocket formation was seen to
improve to the point where there was no pus to be
found, without the use of any dental instrumentation
or other adjuvant except careful cleaning of the
gums and pockets. In the early stages of such a
condition one half grain of emetin hydrochloride was
given daily by hypodermic injection until after the
pus and amoebae had disappeared. In w^hat was
called the early stages of chronic pyorrhoea, with
chronic catarrah of the gum margins, with contrac-
tion, soreness and tendency to bleed, and the forma-
tion of pus pockets beneath, it was recommended
that the emetine treatment be combined with careful
regular dental instrumentation until not only the

116 PROTOZOAN PARASITISM

amoebae and pus had disappeared but the tissues had
healed and become healthy. Otherwise recovery
could not be expected and recurrence of amoebae took
place.

In late pyorrhoea, particularly with deep pus pock-
ets and extension sinuses, extensive tissue destruction,
particularly of the supporting and adhering tooth
attachments, it was recognized that it was most diffi-
cult or impossible to eliminate the amoebae and that
lost tissues could not be fully restored. The extrac-
tion of loose teeth, surgical opening and drainage of
deep sinuses or pockets, the syringing of pockets with
water or saline solution followed by flushing with
0.5% emetine solution, thorough and regular dental
cleaning, in addition to emetine hypodermatically,
were recommended as measures directed at halting
the progress of the disease, but not expected to be
curative measures.

As a research procedure it is needed now to revive
an interest in the treatment of oral amoebiasis in the
light of some of the information which has been
gained since the abandonment of the whole idea.
Stovarsol both locally and taken by mouth as in in-
testinal amoebiasis should be tried. Chiniofon and
the dyes of Koch and the application of heat, these
and other measures, associated with dentistry and
dental surgery, are available for experimentation.
But let all be most carefully controlled and calculated.
Let us not have another spectacle such as occurred
about 1915-1916.

CHAPTER VII

The Amoebae (Continued)

Endolimax nana. lodamoeha butschlii. Dienta-
moeba fragilis. Other Amoebae

ENDOLIMAX (ENDAMOEBA) NANA

This small amoeba was long confused with other
parasitic and free living forms. Although it is a
very common amoeba of man and had been observed
by several protozoologists before that time, it was
first described by Wenyon and O'Connor in 1917.
Its main interest lies in the fact of its commonness
and the liability of confusion with Endamoeba histo-
lytica.

As it occurs in the stool it is inconspicuous in any
but very careful study. It is usually sluggish or
practically non-motile and its small size, 6 to 12 mi-
crons, allows it to be passed by under the eye of a
casual observer. When fresh and kept at body
temperature it is more active. The ectoplasm and
endoplasm are not sharply differentiated, the for-
mer sometimes showing as a clear hyaline rim in the
rounded resting stage. Pseudopodia are ordinarily

117

118

PROTOZOAN PARASITISM

small and sluggish. The encloplasm is granular, the
nucleus within it usually not visible.

The cysts, measuring about 8 to 10 microns in
length, are usually elongated or ovoid and one side of
the rim may be less convex than the other. Seen
fresh they are hyaline bodies without very definite

Fig. 20. — Endolimax nana.

Drawings of specimens stained by iron-haematoxylon. A, tro-
phozoite. X 3500. B, C and D, cysts with one, two and four nuclei.
X 1500.

wall, and the nuclei are invisible. Iodine prepara-
tions of fresh cysts may show the nuclei but not as
clearly as in some other cysts.

For satisfactory study and identification of E.
nana, it is virtually necessary to have well differ-
entiated iron-haematoxylon preparations. In such

OF THE ALIMENTARY TRACT 119

specimens both in active and encysted stages the
nucleus may be correctly observed and upon this de-
pends the identification of the organism.

The nucleus has an inconspicuous rim on which
are no chromatin granules. This material is collected
into the karyosome, which is a comparatively large
irregular chromatin body or collection of granules,
usually well to one side of the nucleus. This body may
show a larger granule on one side and a smaller one
on the other, connected by a thread. The cyst has
four of these characteristic nuclei, commonly in one
end of the cyst.

It may be readily appreciated that the vegetative
form may be confused with small sluggish Enda-
nioeba histolytica and that the cyst may also be falsely
identified as the cyst of that important parasite.
One should be warned, however, by the small size, the
sluggishness of movement, the shape of the cysts, and
the difficulty or impossibility of showing the nuclei
even in iodine preparations. Positive identification
rests upon stained preparations in which the nucleus
can be accurately studied.

Endolimax nana inhabits the large intestine of man
and its visible food bodies are bacteria. Wenyon
(1920) saw it in the lumen of mucous glands in sec-
tions. The writer (1923) failed to find that it in-
vaded ulcers of the rectum in a person who harbored
it in the intestine. There is no indication that it
ever causes harm to its host.

Thomson and Robertson (1925) maintained

120

PROTOZOAN PARASITISM

growth on L. E. A. medium of Boeck and Drbohlav
for nineteen days.

lODAMOEBA BUTSCHLII

There is some confusion about an amoeba of the
human intestine which is fairly commonly seen, the
cysts of which were discovered before the active form

Fig. 21. — lodamoeba butschlii.

A, trophozoite, B, cyst stained by iron-haematoxylon, C, cyst
with dark iodine stained globule. Drawings x 2000.

and called "iodine cysts" by Wenyon ( 1916) . In the
active stage this amoeba resembles somewhat End-
amoeba coli. It usually measures 9 to 13 microns, is
without distinct differentiation of ectoplasm from
endoplasm, and is of sluggish movement. The nu-
cleus is invisible in unstained preparations, as con-
trasted to E. coli.

The cysts, more commonly found than the vegeta-
tive form in stools, are of irregular shape, contain only

OF THE ALIMENTARY TRACT 121

one nucleus, have a definite cyst wall, and character-
istically show a more or less prominent refractive
body staining dark brown in iodine, thus causing the
designation of iodine cysts or 'T cysts."

As in the case of Endolimax nana, carefully dif-
ferentiated stained specimens of this amoeba are
necessary for its identification.

The nucleus is single in all stages, except the rare
occurrence of a bi-nucleated cyst. In the free stage
this body show^s a large central karyosome sur-
rounded by globules between it and the rim. In the
cyst the karyosome is on one side, the other being
occupied by the globular bodies. The glycogen body
is dissolved in the usual staining technique, leaving
a vacuole.

Presumptive identification in practical stool diag-
nosis may be made on the following points:

An amoeba resembling Endamoeha coli, usually
smaller, with no nucleus visible in the active form,
with cysts commonly misshapen, showing in iodine
preparation a large brown globule, and on careful
examination a single nucleus in the cytoplasm not
occupied by the glycogen.

This amoeba is also knowm as lodamoeha wil-
liamsi and Entamoeba nana. It is a fairly conmion
inhabitant of the intestine, w^here it is a harmless lu-
men dweller, its visible food objects being bacteria.

Thomson and Robertson (1925) report its cul-
tivation on the L. E. A. medium of Boeck and Drboh-
lav for fifty-six days.

122 PROTOZOAN PARASITISM

DIENTAMOEBA FRAGILIS

This is an uncommon amoeba of the human in-
testine, first described by Jepps and Dobell (1918).
It is small, 3I/2 to 12 microns, actively motile when
fresh and warm, with distinct ectoplasm and endo-
plasm, the pseudopodia being clear and "leaf-like."

Fig. 22. — Dientamoeba fragilis.

Drawings of trophozoites and cyst from specimens stained by
iron-haematoxylon. x 3000.

The endoplasm contains bacteria upon which the
amoeba feeds.

Characteristic of it are its two nuclei, although these
are usually invisible in unstained specimens. In
properly stained preparations the nuclei show a rim
with a scattering of small granules upon it, a central
karyosome of a group of chromatin granules, con-
nected with the granules on the rim by delicate
threads.

Dientamoeba fragilis is an exceedingly delicate
organism, undergoing early degeneration and disin-

OF THE ALi:\lENTARY TRACT 123

tegration in stools. Its cysts are relatively unknown.
Consequently it is to the ordinary examiner a rare
or unknown amoeba. It is apparently harmless to
its host.

Thomson and Robertson (1925) report its cultiva-
tion on Boeck and Drbohlav's L. E. A. medium.

OTHER AMOEBAE OF MAN

Karyavioehina falcata. Kofoid and Swezy (1924
and 1925) describe a new genus and species of amoeba
from the intestine of man, occurring in six instances
out of 13,894 stool examinations of 3000 persons.
"This amoeba is characterized by one, rarely two or
more, blunt hyaline pseudopodia." Ectoplasm and
endoplasm are sharply separated. The endoplasm
is coarsely vacuolated; food bodies are rare in these
vacuoles.

"The nucleus contains one or two, rarely more,
large crescentic, siderophile masses applied to the
nuclear membrane and little chromatin otherwise
applied to the membrane." There is a "neatly
spherical, eccentric karyosome." Cysts were not
found. The organism resisted treatment for intes-
tinal amoebiasis.

Caudamoeba siijesis. Faust (1923) has described
from cases of amoebic dysentery an amoeba, ingesting
both red'blood corpuscles and bacteria, and moving in
a slug-like manner, having definite polarity, with the

124 PROTOZOAN PARASITISM

nucleus in the forward encloplasm, and the posterior
end dragging behind a mass of attached debris. No
cysts were observed. Confirmatory evidence will be
necessary to show the nature of this amoeba. It
is not clear that it could not be Endamoeba histo-
lytica.

CHAPTER VIII

The Flagellates

Classification. General Considerations. Prevalence
and Relations. Examination for Flagellates.

class : mastigophora.
order : monadida.
genus: trichomonas.

species: T. hominis.
T. buccalis.
genus: chilo^^iastix.

species: Ch. inesnili.
genus: giardia.

species: G. intestinalis.
genus: embadomonas.

species: E. intestinalis.
genus: enteromonas.

species: E. hominis,
genus: tricercomonas.

species: T. intestinalis.

THE FLAGELLATES (FLAGELLATA)

Of the class of Protozoa known commonly as the
Flagellata there are five well established genera oc-
curring in the alimentary tract of man, there is a

125

126 PROTOZOAN PARASITISM

sixth of probable validity and there may be others
of very small size not yet sufficiently identified. The
class has the common characteristic of possessing
flagella, comparatively long lash-like organelles con-
cerned with locomotion and food gathering. Their
bodies are variable in a common "pear" shape.

Probably the majority of protozoologists most fa-
miliar with these organisms now believe the class
to be harmless to their hosts, although some hold the
question open. Among medical people there exists
the greatest confusion as to the different genera and
species and as to their effect on their hosts, a great
many practitioners believing that at least some of
them are disease producers. To these such terms as
''flagellosis," flagellate infection, flagellate diarrhoea,
and flagellate dysentery, relate to clinical states of
more or less definiteness in their minds.

In many medical laboratories the only names
known are "flagellate," Trichomonas, or ''Cercomo-
nas/' and the finding of such an organism in the stool
is sufficient evidence for the institution of treatment
of the conditions supposed to be due to it. The con-
fusion is so great that it is necessary to discount or
ignore the bulk of medical report on the subject.

There exists no reason why any examiner may
not easily identify the common flagellates of the ali-
mentary tract of man. Trichomonas, Chilomastix, and
Giardia, although the very small ones, Emhadomonas,
Tricercomonas, and Enter oinonas, require consider-
able acuteness.

OF THE ALIAIENTARY TRACT 127

The problem of the effects of these parasites upon
man has reached a stage of impasse. None of the
class has been shown to be an actual tissue invader
or destroyer, none has been shown to produce any
substance or bring about any state deleterious to the
host. There is no positive direct evidence on the
question, it is all clinical circumstantial evidence
based upon the occurrence of indefinite symptoms of
abnormal states associated with the presence of the
parasites. Such evidence, if it were definite and
characteristic, would weigh more than it does. There
is no typical or characteristic clinical complex to
be related to the presence of any of them.

Until better identification of the organisms and
more careful relation of them to definite clinical
states is done in medical practice the question will
remain as it is, unless experimentation develops more
bearing than it has.

It was thought that cultivation, Avhich may now be
done with all except Giardia, would initiate some di-
rect avenue of approach, perhaps through isolation of
the organisms and experimental infection. Thus far
this has not occurred, cultures have not been devel-
oped which are usable in such work. Neither is
animal experimentation satisfactory. It is most
difficult to judge or control the absence of like para-
sites in experimental animals.

The species of flagellates found in the alimentary
tract of man are apparently specific for him. We
probably do not obtain these organisms from other

128 PROTOZOAN PARASITISM

animals but from each other. They are transmitted
from person to person more or less directly. Close
personal contact, faulty personal toilet hygiene, un-
sanitary disposal of human excrement, contamination
of water, milk, and food, exposure of excreta and food
to flies, all are factors in the spread of these parasites.

Some of the species are very common, although
varying in incidence in different quarters. All are
of world-wide distribution. With the commonness
of Trichomonas, Chilomastix, and Giardia in the gen-
eral population of the world, it is readily appreciated
that a certain percentage of the sick who come under
the care of the medical profession will show one or
more of them. It may be conservatively estimated
that from twenty-five to fifty per cent of people in
any region will be found to harbor an intestinal fla-
gellate and that practically all people give tenantry
to one or more at some time.

The fundamental fault, it seems, in most clinical
studies of "flagellosis" is the lack of control study.
It is recognized that proper scientific control of such
studies, which do not lend themselves to experimen-
tal confirmation, is most difficult. Having in mind
to compare a considerable group of flagellate hosts
to a similar group of non-parasitized, the writer
(1926) made an analysis of 1040 consecutive clinical
cases in whom gastro-intestinal studies had a prom-
inent place on account of the symptoms displayed,
the study being spread over a period of about four
years.

OF THE ALIMENTARY TRACT 129

From only one stool examination, as a rule, of
each, 23% of this number harbored flagellates as
follows: Trichojnonas hominis 12.5%, Chilomastix
mesnili 7.5%, Giardia intestinalis 2.3%, Tricer-
comonas 1.5%, unidentified flagellates 1.7%.

In this series the incidence in the warm months
was above the average (27% ) and in the cold months
below (15% ), showing that, as a class, warm weather
gives better opportunity for their spread and, also,
that spontaneous elimination must take place.

City dwellers and those living in rural districts
were similarly infected, 71% of the flagellate hosts
and 70% of the free living in the city. From this
observation it seems apparent that modern sanitary
facilities, which existed in the places called cities
here, do not prevent the spread of the flagellates.
This has been observed by others, particularly in in-
stitutional surveys. Close personal touch, person to
person transmission, seems to play a large part in
their dissemination.

Males were slightly more commonly parasitized
than females, 47% of the flagellate hosts and 40%
of the free being males. Smithies (1926) has made a
similar observation. Of his 265 patients harboring
intestinal protozoa 172 were males. Perhaps men,
by coming in contact with more people, come more
into contact with the flagellates.

Forty-three per cent, of the flagellate infested
patients were below forty years of age and 68% w^ere
below fifty, while in the flagellate-free group 53%

130 PROTOZOAN PARASITISM

were below forty and 83% were below fifty. The
later years of life increase the liability, perhaps from
cumulative contact and infection, perhaps in relation
to certain other states which are more concerned with
later life.

One of these possibly related states is that of rela-
tive or actual gastric anacidity. Thirty-two per cent,
of the parasitized patients showed no free hydro-
chloric acid, w^iile this condition was present in but
19% of the flagellate-free. On the other hand, 25%
of the flagellate-free showed hyperchlorhydria, while
this was the case in but 10% of the flagellate hosts.
The remainder, 57% of the parasitized and 56% of
the free, in round numbers, were in the normal region,
counting broadly any acid up to fifty degrees as "nor-
mal." Does this more frequent finding of hyper-
chlorhydria in the flagellate-free and of achlorhydria
in the parasitized mean that flagellates are instrumen-
tal in pathologic states which lead to decrease in acid
secretion, or does lowering of the acid barrier in the
stomach explain the higher incidence of the flagel-
lates? Experimentally Trichomonas homiins had a
few survivors in 0.1% hydrochloric acid in 0.9%
sodium chloride solution at the end of two hours in-
cubation. It w^as entirely destroyed within this time
by stronger acid solution. Chilomastix viesnili sur-
vived acid exposure even better than did T. ho minis,
being still active at one and one-half hours in 0.1%
and 0.2% HCl in 0.9% NaCl solution, but 0.3% acid
killed within one half hour. Giardia intestinalis

OF THE ALIMENTARY TRACT 131

trophozoites failed to survive a similar exposure to
0.1% acid for even a few minutes, although the writer
has seen it active in gastric content in a state of achlor-
hydria. Of course, Chilomastix mesnili and Giardia
intestinalis have encysted phases in which they must
be more resistant, but it is not unlikely that C. mes-
nili in active stage may pass the stomach as well as
does Trichomonas hominis, although the former is
killed rapidly by water alone.

Gastric and duodenal ulcers are conditions in which
hyperchlorhydria is common. They are also re-
lated to early life as contrasted to chronic chole-
cystitis, for instance. There w^as a clinical diag-
nosis of peptic ulcer in 10% of the flagellate-free but
none in the others.

On the other hand, there was recorded a clinical
opinion of chronic cholecystitis, some proven, the
majority not, in 38% of the parasitized and 22% of
the free. Chronic cholecystitis is a state of disease of
later life and is commonly accompanied by lowered
gastric acidity, both of w^hich states were shown in
definite relation to high flagellate incidence. Chronic
cholecystitis is one of the conditions in which a ten-
dency has been noted to incriminate intestinal pro-
tozoa and, considered separately, these observations
could be taken as evidence in favor of such a view.
As against such reasoning, however, one has to ac-
count for 22% of the flagellate-free who had the same
diagndsis. In a debate one could say that it would
be equally reasonable to so explain the higher in-

132 PROTOZOAN PARASITISM

cidence of arterial disease occurring in the flagellate
hosts.

A condition of chronic appendicitis — thought by
some physicians to be sometimes produced by intes-
tinal protozoa — was diagnosed in 22% of the fla-
gellate infested and in 25% of the free.

Diarrhoea, the condition longest and most com-
monly ascribed to the flagellates, was present at the
time of examination or conspicuous in the past his-
tory of 9% of the parasitized and 8% of the free.
When diarrhoea was present there was no gross or
microscopic characteristic feature. It was impos-
sible to say that a watery stool or a frothy gassy stool
was distinctive of the presence of flagellates. Con-
stipation was much more prominent but of practically
the same proportion in both groups, 57% of the
parasitized and 55% of the free.

The benzidine test for chemical blood in the stool
was positive in 67% of the flagellate hosts and 71%
of the others, this observation being considered only
of comparative significance. Similarly to be used
is a clinical opinion of colitis in 6% of the parasitized
and 119^ of the free.

Blood counts and haemoglobin estimations re-
vealed no apparent differences between the two
groups, and nothing could be made of any attempt to
relate various nervous system disturbances, which
may be indicated by the term ''neurasthenia," to the
parasitized group more than the other.

Arthritis deformans, which Barrow (1924) found

OF THE ALIMENTARY TRACT 133

in 11% of his protozoa infested cases and in which
disease he found 100% intestinal protozoa infection,
was conspicuous by its absence, there being no re-
corded case in the parasitized group. The search
for this disease in the records of the flagellate hosts
was done as an afterthought, the records of the others
were not examined with this in view.

It will be seen that in such a study there is little
or nothing to produce as evidence in favor of harm-
ful effect of flagellates upon their hosts, but rather
to the contrary.

EXAMINATION FOR FLAGELLATES

In examining for flagellates in feces it is well to
have a procedure which fits with that of search for
amoebae. It is the practice of the writer to ask
for a fresh stool produced by a saline purgative, un-
less there is diarrhoea. As contrasted to the amoe-
bae it is the active form, the trophozoite, which is
most practically discoverable with the flagellates.
Unless the stool is really fresh and liquid, tropho-
zoites which are present may not be seen or at least
not so readily. Numerous surveys giving a low inci-
dence to Trichomonas were made on stools which
were not fresh.

Mixed on a microscopic slide with 0.9% sodium
chloride solution to a thinness so that, when cov-
ered, vision is clear, and examined with a low dry
objective, feces will ordinarily reveal the active or-

134 PROTOZOAN PARASITISM

ganisms immediately when considerable numbers are
present. Prolonged examination of several prepara-
tions will usually reveal sparse infection. When
picked up by low magnification they may be then
studied under higher power objectives.

Mixing a portion of the specimen wdth 0.9% sodium
chloride solution and placing in the incubator for a
short time, until well warmed, will activate organisms
which have become sluggish and will reveal parasites
otherwise overlooked.

It is seldom that the trophozoite of a flagellate
does not appear in a liquid stool examined properly
immediately after passage or after being kept warm
for a short time, when it is present in the intestine.
For that reason the cysts are relatively unimportant
from the standpoint of such an examination. They
are more important in survey work, when large num-
bers of specimens are to be examined, or when ex-
amination cannot be done immediately. Such ex-
aminations are likely to miss Trichomonas and other
flagellates when they are present only in the active
stage.

The active forms of the flagellates are readily
identifiable and there is little or no excuse for con-
fusion of them, except some of the more minute un-
common species. Even in the most actively motile
state, one learns to recognize Trichomoiias, Chilo-
mastix and Giardia by their manner of movement.
Giardia has an easily recognized shape. Seen antero-
posteriorly it is of pear shape with broad anterior

OF THE ALIMENTARY TRACT 135

and tapering posterior extremities. A lateral view
shows the broad concave indentation anteriorly and
ventrally. It swims with a peculiar vibratory mo-
tion of the body and frequently flexes the tail to the
anterior end. Chilomastix has a stiff inflexible body
of the shape of a carrot. It swims in a character-
istic ^'corkscrew" forward. Trichomonas has a typi-
cal darting motion, moving very rapidly when most
active, frequently stopping and anchoring by its pos-
terior end to a clump of debris, while it whips the
solid particles about with its flagella in violent man-
ner. It has a very flexible plastic body, twisting
and turning, crawling among masses of solid parti-
cles. The undulation of its surface '^ruffle" is most
characteristic. When specimens have been exposed
for a time and become sluggish. Trichomonas de-
velops an undulating movement of the surface of the
body, probably a slow movement of a relaxed un-
dulating membrane, and the flagella may move so
slowly that they can be readily seen or even counted.
In such a state Giardia and Chilomastix remain rigid,
their form and shape does not change, their flagella
gradually cease motion, hanging as idle threads, while
the undulating flagellum within the ventral groove
may continue a sinuous motion.

Most painstaking study and carefully stained
specimens are necessary for identification of the un-
common more minute species, Einbadomoiias intes-
tinalis, Tricercomonas intestinalis and Enter omonas
hominis.

136 PROTOZOAN PARASITISM

The cysts of Giardia intestinalis and Chilomastix
mesnili may show m diarrhoeal or purged stool or
they may occur only in a natural formed stool.
Giardia cysts are commonly numerous; they are
ovoid, of ground glass appearance, reveal their inner
structure in iodine preparation, and are readily dis-
coverable. A small ovoid or slightly elongated
^'ground glass" body which shows ^^eyes" (the nu-
clei) in one end on careful observation, is likely to
be a G /arc? ia cyst.

Cysts of Chilomastix mesiiili are not nearly so
readily found. In diarrhoeal stool or purged speci-
men the trophozoite may be the only form. When
present in a natural stool their number is variable
and prolonged search may be necessary to find them.
They are smaller than Giardia cysts, are typically
pear or lemon shaped, are of uniform size, "ground
glass" appearance, and show in iodine preparation a
dot on one side anteriorly (the nucleus). They are
apt to be confused with yeasts by the inexperienced.

Specimens stained by the iron-haematoxylon
method are necessary in case stools are not to be ex-
amined in a reasonable period of time. Stained speci-
mens are essential for study of the finer details of the
organisms, the flagella, the undulating membrane,
nucleus, food bodies, etc. For the inexperienced
such preparations are necessary for the identification
of the cysts. In carefully prepared specimens stain-
ing by the ordinary blood film methods, such as
Wright's or Leishman's, may give beautiful demon-

OF THE ALIMENTARY TRACT 137

stration of the flagella, undulating membrane, the
cytoplasm and its food bodies, but these stains do not
give nuclear detail and are generally of little or no
service in differentiating protozoa.

A little careful study and practice will enable the
laboratorian to dispense with time consuming and
difficult staining methods in routine examination for
flagellates in feces. Similar fresh unstained prepara-
tions from the gums and vaginal vault are satisfac-
tory for discovery of Trichomonas in these locations.
In urine the ordinary microscopic examination
of ^-centrifugalized specimens will reveal Trichom-
onas when present. One must, however, be contin-
ually on guard against free living forms which may
come from water in specimen bottles or from solutions
used in the examinations or may grow in specimens
allowed to stand. Fresh specimens taken in dry
clean containers are essential to avoid confusion and
even then one will occasionally encounter a free liv-
ing flagellate. Check of the water and solutions
used about the laboratory will commonly reveal the
source of a perplexing flagellate.

Hegner and Becker (1922) and Hill (1926) have
recommended the culture method as a practical meas-
ure for routine diagnosis or field surveys. The need
for such methods in medical practice is not impres-
sive; the greater need is for careful routine practices
in stool examination and careful identification of the
discovered organism. Culture methods, even yet,
are crude at best, and they are not easy of application.

138 PROTOZOAN PARASITISM

Giardia has not been cultivated and would not be
revealed in such studies. Few, if any, intestinal
protozoa will be found by the average labor at or ian by
culture when not by measures here outlined, if prop-
erly carried out. Later, perhaps, but now we are
interested in avoiding further confusion and of clear-
ing some which exists.

CHAPTER IX

The Flagellates (Continued)

Trichomonas Species. Cultivation. Trichomonas hom-
inis. Prevalence and Relations. Habitat and Effects.
Treatment. Other Intestinal Trichomonads.

TRICHOMONAS

When considered by genera Trichomonas is the
most common flagellate of man's alimentary tract, in
the writer's experience. Trichomonas homiyiis is the
inhabitant of the intestine while Trichomonas buc-
calis occurs in the mouth.

It is not yet clear that these two are distinct
species, or what their relation is to Trichomonas
vaginalis, the habitat of which is the vagina. In
their own natural locations these three trichomonads
of man may have somewhat different appearances.
Trichomonas vaginalis may be larger, and it and Tri-
chomonas buccalis usually swdm about less actively
than does Trichomonas hominis, as it is seen in liquid
feces. When seen in culture, however, it is thus far
commonly impossible to say from w^hich source the
organism came.

In fact, Hegner (1928), by experimentally estab-

139

140 PROTOZOAN PARASITISM

lishing infection of fowls with trichomonads from
seven different species of animals, raises the question
whether these may not be a single species and not
separate as now generally regarded.

The same investigator (1928) by producing infec-
tion of the vagina of monkeys with monkey trichom-
onads of intestinal and vaginal origin, brings this ex-
perimental evidence in support of the morphological
resemblance between the parasites of these two loca-
tions, to which he and Ratcliffe ( 1927) had previously
referred.

The present writer (1915) reported upon Trichom-
onas from the vagina and mouth of the same individ-
ual, which was morphologically and culturally the
same organism and was, therefore, designated as Tri-
chomofias vaginalis, that being the acceptable name
in that case. Later Ohira and Noguchi (1917) cul-
tivated the mouth trichomonad and, considering it
distinct from Trichomonas vaginalis, called it Tetra-
trichomonas hominis, a name not available since the
organism is identified as belonging to the genus Tri-
chomonas, which, with Trichomonas vaginalis as the
type species, has four flagella, not three as assumed
by these writers, and since the specific name hominis
was already applied to the species in the intestine.

Goodey (1917), a bit later, named the mouth tri-
chomonad Tetratrichomonas buccalis, but since Tet-
ratrichomonas is a synonym to Trichomonas their
corrected name is Trichomonas buccalis.

The writer (1922) called attention to Steinberg's

OF THE ALIMENTARY TRACT 141

(1862) three names, Trichomonas elongata, Trichom-
onas caudata, and Trichomonas flagellata, for Tri-
. chomonas of the mouth, the first of which, by priority,
should be the valid name, although Kofoid's (1920)
acceptance of Trichomonas buccalis was taken as ex-
pedient. Wenyon (1926) adopts Trichomonas
elongata as the correct name for Trichomonas of the
human mouth.

Lynch (1922) cites the morphological resemblance
of the trichomonads of Ohira and Noguchi and of
Goodey with Trichomonas from the vagina and
mouth in his studies and is of the opinion that they
are the same organism. It is further called to atten-
tion (Lynch, 1922) that trichomonads may vary in
activity and in size in different environments and
that differentiation in the same medium would seem
necessary to prove the validity of different species
from different sources unless there may be some dis-
tinct feature of difference not now known.

It seems, therefore, not impossible that Trichom-
onas of man is all one organism instead of three.
Further, it seems that the habit of differentiating
and naming protozoa by location is unsound and that
distinction among them should rest upon features
of difference between the organisms themselves.
However, it is conventional at the present to consider
Trichomonas hominis, Trichomonas elongata (buc-
calis) , and Trichomonas vaginalis as distinct species
and this -will be adhered to in this writing.

Trichomonas has been the subject of much investi-

142 PROTOZOAN PARASITISM

gation and experimentation of recent years. The
author (Lynch, 1915A and 1915B), Ohira and Nogu-
chi (1917), Boyd (1918), Pringault (1921), Hogue
(1921) and, more recently, numerous others have cul-
tivated it from various sources. Excellent results
have been obtained with the organism from the
mouth, vagina, intestine, and from urine (Trichom-
onas vaginalis), in liquid human blood serum diluted
with from four to ten parts of 0.5% to 0.9% sodium
chloride solution, Ringer's solution, and Locke's so-
lution, incubated at 37.5° C. The higher dilution
has been attended with more success in the case of
the intestinal trichomonad, the stronger solution
with that from the mouth. Those who are interested
in research in culture methods should consult the
original articles of those who have reported upon
it.

AbiUty to produce prolifically varies in differ-
ent cases, and probably the associated bacterial
growth has much to do with this. All of these media
are slightly alkaline and usually become more so
with the age of the culture. The column of medium
should be rather deep, and the organisms may be
taken from the bottom of the tube with a capillary
pipette. The numbers are usually greatest at about
the third or fourth day but some may live for twelve
days or longer. Subculture should be planted on the
second or third day.

Hinshaw (1927) gives the simplest medium he has
used as composed of 100 cc. of Locke's solution with

OF THE ALIMENTARY TRACT 143

10 cc. of 10% casein, tryptic digest, while the medium
of most proHfic cultures was composed of the solidi-
fied egg slant of Boeck and Drbohlav, given in the cul-
tivation of Endamoeha histolytica, covered by a
liquid composed of Locke's solution 1000 cc, with
the white of one egg and rabbit blood serum, one drop
to each 2 cc. The blood serum was added asep-
tically to each tube, introduced at the base of the
slant just before inoculation of the culture. This
investigator believes that the split products of pro-
tein are essential in the cultures and that bacteria
are necessary for the purpose, he having failed to
grow Trichomonas in the absence of bacteria. On
the other hand, some bacteria were definitely harmful
to the growth of the protozoa.

Cultivation of Trichomonas, in the writer's ex-
perience, while subject to success in considerable
proportion and in a variety of media in which a pro-
tein in solution in a physiological salt solution are
the essentials, is in a measure uncontrollable. We
do not know, except in a very rough fashion, what
the essential elements are. When we do we shall be
able to cultivate it without bacteria. The culture
method does not seem available for general practical
use at the present. Most of the methods described as
successful will fail at times under exact imitation,
so far as is possible, of other occasions when they
succeed.

144 PROTOZOAN PARASITISM

TRICHOMONAS HOMINIS

The trichomonad of the human intestine, Tri-
chomo7ias hominis, is apparently variable in its prev-
alence in different localities, at least so in the experi-
ence and reports of reliable students of it.

Craig (1926), from an analysis of several studies
by Kofoid, Kornhauser and Plate in the United
States, Mathews and Smith and Jepps in England,
Faust in China, and from his own observations, is of
the opinion that this organism is the least common of
the better known intestinal flagellates. He believes
that it is present in only from 0.5% to 1% of the in-
habitants of temperate regions.

Compiling the results of a number of reports pub-
lished by English, American and French investiga-
tors from 1916 to 1919, Hegner and Payne (1921) ar-
rive at an average incidence, in 20,000 reported cases,
of 3% for Trichomonas hominis.

Boeck and Stiles (1923) give an incidence, in 8029
persons examined by them, of 0.007%. However,
the conditions of their examinations did not favor
trophozoites and probably this organism was largely
missed.

Jepps (1923), examining 674 Tamils and 350 Chi-
nese in the same hospital, found Trichomonas hom-
inis in 16.5% of the former and in 2.2% of the latter.

Barrow (1924) found less than 2% in 725 of his
patients harboring some type of intestinal proto-
zoon. He found an incidence of 8.3% in 79 cases of
arthritis deformans.

OF THE ALIMENTARY TRACT 145

Smithies (1926) found 2% of 3780 patients hav-
ing some gastro-intestinal disturbance to harbor Tri-
chomonas hominis.

Thomas and Baumgartner (1925) found only
0.26% infestation of 1122 inmates of a New York
state school for feeble-minded women.

Hegner (1925) found 20.6% of 286 patients in
hospitals of Central America to harbor the parasite,
this from only one examination.

Hill and Hill (1927) found it in 20.9% of children
of pre-school age in Porto Rico.

The writer (1926) found 12.5% of 1040 cases of
chronic disease having some reference to the gastro-
intestinal tract to show Trichomonas homiJiis on
about one examination per person. It is believed
that more than 10%, probably nearer 20%, of the
inhabitants of w^arm countries will show Trichom-
onas hominis on correct examination.

It seems probable (Lynch, 1928) that Trichom-
onas infestation of the intestine is more related to
rural life and to warmer climates. This opinion, de-
duced from comparative studies, is consistent with
the life of the organism. It is a naked, non-encyst-
ing flagellate of remarkable ability to survive ex-
posure.

On account of its non-encystment it is very sus-
ceptible to drought.

Hegner (1928) finds that a temperature of 41 °F.
(5°C.), does not effect the viability of the organism
beyond that of room temperature (70°F.), that feces
deposited in wet garden soil retained viable organ-

146 PROTOZOAN PARASITIS^NI

isms for as long as seven days, but that a sandy
soil bed led to disappearance by culture after twelve
hours. He found the viability of the organism in
water to vary with dilution, such dilution as would
occur when a stool is w^ashed into a pond or stream
giving little or no opportunity for survival and trans-
mission of the organisms. This is an interesting
observation, since it has a direct bearing on the
means of transmission, commonly believed to be im-
portant. Others have found Trichovionas resistant
to water. The writer's experiments on the point
are contradictory and indicate an uncontrolled fac-
tor. At one time neither tap water or distilled water
effected Trichomonas hominis in a test tube in the
incubator for about three hours. At another time
tap water killed wuthin two hours. At still other
times, controls for cultures, in tap water, incubated
overnight, failed to survive, but a similar failure has
occurred in physiological saline solutions. The
vomitus and feces of flies fed on feces containing
Trichomonas hominis produced viable organisms at
various intervals between twenty minutes and six
hours after ingestion. Cockroaches were not found
to pass viable organisms after ingesting them. Tri-
chomonas hominis in feces w^as destroyed by 2%
carbolic acid in 5 minutes, 1% creolin in 5 minutes,
and 0.5% lysol in 5 minutes.

Trichomonas hominis is a pearshaped flagellate
measuring from 5 to 15 microns in length. When
very active it darts about in quick motion, swimming

OF THE ALIMENTARY TRACT 147

freely in liquid, revolving as it goes, crawling, twist-
ing and pushing its way through clumps of debris.
Its body is flexible and it may elongate, contract and
turn at will. When sluggish it may have surface
pseudopodia. It has four flagella attached at the
anterior end to a group of granules, the blepharo-
plast. It possesses an undulating membrane, the
border of which (axoneme) originates at the same

Fig. 23. — Trichomonas hominis.

Drawings of specimen unstained (A) and stained (B) by iron-
haematoxylon. x 2000.

place as the flagella and may extend posteriorly as
a free flagellum. The base of the undulating mem-
brane is supported by a fibre of similar origin. The
flagella move in rythmic lashings, sweeping materials
against the ingesting surface, the undulating mem-
brane waving synchronously with the lashing of the
flagella. The undulating membrane extends di-
agonally posteriorly for the whole or greater part

148 PROTOZOAN PARASITISM .

of the length of the body. A skeletal or stiffening
structure, the axostyle, extends from the region of
the nucleus through the length of the body and pro-
jects as a sharp spine from the surface near the
posterior end. There is an indistinct slit or cyto-
stome at the anterior end near the origin of the flagella
opposite to the undulating membrane.

The nucleus is near the base of the flagella and
undulating membrane, is invisible in ordinary active
unstained specimens, and its detail is not easily stud-
ied even in stained specimens. It is ovoid and has
a definite membrane. The distribution of chromatin
is not well described, the karyosome is considered
to be central.

The division of the organism is by binary fission,
the nucleus undergoing mitosis, according to Kofoid
(1915).

In division the body increases in size, it becom-
ing increased laterally more than longitudinally.
The nucleus divides and probably the axostyle and the
undulating membrane split longitudinally from be-
fore backward. The flagella apparently do not split
but are evenly divided between the two new organ-
isms. The appearance of the dividing organism be-
comes shield shaped with an indentation between
the two new anterior poles, which may have two
flagella each. The undulating membrane may be
separated anteriorly and joined posteriorly. An-
terior schism proceeds until the organism is com-
pletely divided, the posterior extremities adhering

OF THE ALIMENTARY TRACT 149

for a time before the organisms swim separately.
By this time the complement of organelles of each
is usually complete. Such division may be watched
in cover glass preparations from cultures.

If Trichomonas hominis ever encysts it is un-
known. The writer (1915 and 1916) erroneously de-
scribed two cysts for the organism, the first was
Blastocystis, which had been so described by Ucke
(1908), by Bohne and Prowazek (1908), and Bensen
(1901). The second, an original error, was the cyst
of Chilomastix mesjiili, not well known at that time.

HABITAT AND EFFECTS

The natural habitat of the intestinal Trichomonas
is the colon, particularly the caecum.

After ingestion it passes through the stomach and
small intestine but probably does not become seated
until it reaches the caecum.

It is apparently solely a lumen dweller. Wenyon
(1926) found it once in the lumen of the glands of
the large intestine and passing from the glands into
the interstitial tissue. He states that the intestinal
Trichomonas of the guinea pig, Trichomonas caviae,
often invades the wall of the large intestine, which
shows ulceration, in that animal. Wenyon thinks
that tissue invasion may occur and cites the observa-
tions of Pentimalli (1923), who found the organ-
ism in, the blood, and Kessel (1925), who saw it in the
pus of an amoebic liver abscess, but does not know

150 PROTOZOAN PARASITISM

that this is an indication of pathogenicity. Hogue
(1928) has grown Trichomonas in tissue cultures of
epithelium, fibroblasts and sympathetic nerve fibers
without apparent injury to these cells.

The work of Hadley (1916), who thought the
tissue invading parasite of turkeys in the disease
Blackhead was a Trichomonas, has not been sup-
ported.

Experimental infection, such as recorded by the
writer (1915), has not shown the production of dis-
ease in a convincing way. Such experiments are
subject to a variety of error.

The occasional observation of a red blood corpus-
cle ingesting trichomonad cannot be held to indi-
cate any pathogenic role according to Hegner (1928),
who induced eight species of Trichomonas from as
many different animals to ingest red blood corpuscles
from seven different species of animals, in culture
tube.

An experiment of the writer in which Trichomonas
hominis, as well as Blastocystis, was cultivated in a
medium composed of one part of the host's own blood
serum to nine parts of 0.9% sodium chloride solution,
suggests that there are no inhibitory or destructive
antibodies produced by the host and, therefore, proba-
bly no toxic absorption.

The condition which most often calls attention to
its presence and in which it is most often suspected
of an etiologic role is diarrhoea, with frequent watery
stools of no peculiar gross or microscopic character.

OF THE ALIMENTARY TRACT 151

Here it must be kept in mind that, in case para-
sitism exists, diarrhoea would bring the organism
in activity and numbers not ever seen in the natural
stool. It must, also, be recalled that an intestinal
state in which there is inflammatory exudation, with
liquid content throughout its course, would furnish
most excellent opportunity for multiplication of the
organism and it would naturally tend to appear in the
liquid stool in unusual numbers. It would furnish
excellent conditions for cultivation. The adminis-
tration of a purgative may bring out tremendous
numbers when they may be scant or unobserved in
the natural stool.

The common vague clinical state, in which there is
nervous debihty, deficient appetite, "indigestion,"
with occasional attacks of diarrhoea in a chronic state
of constipation, flatulence and gaseous eructations,
abdominal discomfort of indefinite kind, and various
systemic dysfunctions, which is at times laid at the
door of Trichomonas hominis, is such a common state,
regardless of Trichomonas, that it cannot be said at
the present whether it may be ever due to this para-
site.

The writer (1928) found that it had no particular
relation to any age period, 53% of Trichomonas hosts
being below 40 years of age and 78% below 50, while
of the flagellate-free 53% were below 40 and 83%
below 50. Children and the aged were found in-
fected. ,

Nineteen per cent, of the flagellate-free group of

152 PROTOZOAN PARASITISM

this study, and 23% of those who harbored Trichom-
onas hominis showed a condition of gastric anacid-
ity. Twenty-five per cent, of the flagellate-free and
but 14% of the carriers of Trichomonas hominis
had gastric hyperacidity. Experimentally Trichom-
onas hominis is mainly destroyed in 0.1% HCl in
0.9% sodium chloride solution in two hours, and all
are killed by stronger acid mixture.

There was a history of diarrhoea in 8% of the free
and 6% of the parasitized, while 55% of the former
and 50% of the latter were habitually constipated.

There was no change of the blood or other ab-
normality which was not equally conspicuous in the
two groups, except that the records of the hosts of
Trichomonas hominis showed a clinical diagnosis of
chronic cholecystitis in 44% as against a like diag-
nosis in 22% of the controls.

Those who are convicted of the pathogenicity of
the parasite will consider this as distinct evidence
in favor of that belief, while those who are opposed
will ascribe it to the creation in this clinical state
of conditions more favorable to the seating and sur-
vival of the parasite in the intestine, particularly in
favor of it being able to pass the stomach. It must
be borne in mind that a clinical diagnosis of chronic
cholecystitis is itself an indefinite thing.

The writer has used the term "Trichomoniasis" as
relating to the activities of Trichomonas in man, at
that time believing it to be definitely a disease pro-
ducer. More mature observation, however, and

OF THE ALIMENTARY TRACT 153

analysis of the work of others, forces one to reason-
ably retain an open mind. There exists at the present
no definite evidence of the pathogenicity of this
organism; most positive evidence is opposed. On
the other hand, however, there exists no definite
proof that it may not cause harm to its host. Tri-
chomoniasis, then, means at the present only the state
of carrying Trichomonas. Dobell (1921) is horri-
fied by the term. Perhaps it was a premature desig-
nation of a state not sufficiently proven, but if it is
never proven as a disease state the term will never be
used or needed.

TREATMENT

To speak of treatment, either preventive or cura-
tive, of an infection, when obviously it is not known
whether it should be treated, is also premature.

Prevention of the spread of the parasite apparently
needs particularly the proper disposal of human ex-
creta, the prevention of its use as fertilizer for gar-
den stuff, sterilization by some such agent as 0.5 to
1% lysol in case of lack of proper sewage disposal,
the control of flies, the protection of excreta and food
from them, and more careful personal hygiene. The
fly and the human being of fly habits are the sources
of spread.

The writer knows of no specific treatment which
may be depended upon to eliminate Trichomonas
hominis'irom the intestine.

Various drugs have from time to time been claimed

154 PROTOZOAN PARASITISM

to destroy it. Critical examination disproves these
claims, largely or wholly.

Emetine, mercury, salvarsan and various arseni-
cals, methylene blue, and others have been recom-
mended.

The claims of those who recommend the various
intravenous arsenicals seem to need substantiation,
since a number of people who have had extensive
courses of antisyphilitic treatment by these drugs
harbor the organisms. Neoarsphenamine in dilution
of 0.45 gms. in 100,000 up to 0.45 gms. in 1000 in 0.9%
sodium chloride solution has no effect on the motility
of Trichomonas hominis in one hour and in the higher
dilution it survives and is active at twenty-four hours.
Neosalvarsan, as strong as 0.45 gms. in 1000 cc. of
0.9% sodium chloride solution, has no appreciable
effect at one and one-half hours. Sulpharsphena-
mine in similar mixture has no effect at one hour.
The latter apparently effects the organism by direct
application before the former does.

It must be recalled that the number of trichom-
onads in the intestine and in the stool varies widely
without therapeutic influence and that the finding
of a few organisms or none at an examination or on
repeated examination does not necessarily indicate
that any therapeutic agent was responsible.

While Trichomonas hominis is at times a per-
sistent parasite and may remain for long periods, it
undoubtedly spontaneously dies out. Otherwise the
increasing years would show higher incidence, and

OF THE ALIMENTARY TRACT 155

we would all probably come to be hosts before reach-
ing old age.

Diet and the intestinal flora may have much to do
not only with the number of the parasites in the in-
testine but with its gaining foothold and its survival.
Hegner (1923) found that a vegetable diet would in-
crease and a carniverous diet would decrease the fla-
gellates in rats. Ratcliffe (1928) found that this
effect of high protein diets is for the most part due
to the influence on the multiplication of proteolytic
anaerobes in the rat's intestine. The most effective
protein was casein, and beefsteak to a lesser degree.

An exclusive or largely milk diet, either whole
milk or bacillus acidophilus milk cultures, is with-
out effect and the latter may be contraindicated.

It would seem that intravenous medication is not
to be recommended except, possibly, as an experi-
mental measure.

It would be well to give trial to such drugs as
stovarsol, which may be administered by mouth,
accompanied by a diet largely or almost exclusively
of such meat as beef muscle or at least of high pro-
tein content, for a period calculated to develop a
high content of proteolytic flora in the intestine.

Escomel (1913 and 1917) claims to cure infection
of intestine or vagina with Trichomonas by the use of
turpentine, in the intestinal infection using the drug
by mouth and by enema. He gives a tablespoonful
of the following mixture every two hours for three
days: oil of turpentine, 2-4 gms., camphorated tine-

156 PROTOZOAN PARASITISM

ture of opium, 6-12 gms., acacia, 120 gms., syrup
acacia, 30 gms. During this time the diet is re-
stricted to carbohydrates and rice water. At the
same time he gives from one to three retention ene-
mas of 15-30 drops of oil of turpentine, with 10 drops
of tincture of opium, and a beaten egg yolk, in 4
tablespoonfuls of boiled water. This therapeutic
enema follows an evacuating injection.

OTHER INTESTINAL TRICHOMONADS.

Derrieu and Raynaud (1914), Chatterjee (1915),
Haughwout and deLeon (1919), and Kofoid and
Swezy (1924) have called particular attention to a
subgenus of Trichomonas carrying five anterior flag-
ella instead of four. From time to time trichomonads
of man have been described without the regulation
number of flagella. Kofoid and Swezy (1923) name
the five flagellated organism, Pentatrichomonas, the
specific name for that of man being P. ardin delteili,
and the three flagellated form Tritrichomonas.

Pentatrichomonas in man is given special signifi-
cance by some of these writers on account of finding
it in cases of dysentery and also its habit of ingest-
ing red blood corpuscles. Kofoid and Swezy have
cultivated the organism and determined its survi-
val in rain, tap and creek water for three days.

CHAPTER X

The Flagellates (Continued)

Trichomonas elongata. Relations. Morphology. Hab-
itat and Effects. Treatment. Trichomonas vaginalis.
Prevalence. Transmission, Habitat and Effects. Treat-
ment.

TRICHOMONAS ELONGATA (BUCCALIS)

As previously discussed, the Trichomonas of the
mouth of man was given three names by Steinberg
(1862), Trichomonas elongata, Trichomonas caudata,
Trichomonas flagcUata, he thinking he observed
three varieties. The writer (1922) called attention
to the priority of Steinberg's naming over that of
Goodey, Tetratrichomonas buccalis, although con-
forming to Kof old's acceptance of the corrected name,
Trichomoiias buccalis (Goodey). This was because
Trichomonas buccalis had come into common usage.
Following the example of Wenyon (1926), however,
it is concluded that the first name used by Steinberg,
Trichomonas elongata, is the correct one.

Tricho7nonas elongata has not been, with certainty,
differentiated from Trichomoiias vaginalis or Tri-
chomonas hominis and should it be shown to be

157

158 PROTOZOAN PARASITISM

identical with either or both, its name will be sup-
planted.

The writer (1915) studied trichomonads in the
vagina and mouth of the same woman and is of the
opinion that even if Trichomonas elongata (huc-
calis) is a valid species, Trichomonas vaginalis may
occur in the mouth. In direct preparation and in
culture the organisms from the two sources were in-
distinguishable.

Wenyon observed the organism in pus from the ton-
sil and it has been seen in sputum, supposed to have
come from the lung, and in gangrenous abscesses of
the lung at autopsy.

The writer (1915 and 1922), Ohira and Noguchi
(1917), Hogue (1926), Hinshaw (1926-1927), and
others have cultivated this organism in a variety of
media, particularly in blood serum diluted with phys-
iological saline solutions in deep columns of the
tubed medium or as supernatent fluid on the egg
slant of Boeck and Drbohlav, as given in the cultiva-
tion of Endamoeba histolytica.

Trichomonas elongata (huccalis) was found by
Hinshaw ( 1926) in 57 of 186 persons, all having pyor-
rhoea. He believes that it is very common in ad-
vanced pyorrhoea but not present in normal mouths,
and that culture methods are necessary to reveal its
presence in many instances. Hogue (1926) found it
in 9 of 50 persons selected at random, all by smear
preparation, and all hosts being the subjects of dis-
eased gums or teeth. Six of twenty-nine dogs bore

OF THE ALIMENTARY TRACT

159

the infection, according to Kofoid (1929). Heg-
ner and Ratcliffe (1927) found 22 of 23 dogs harbored
a similar organism.

The form of Trichomonas elongata is the character-
istic pear shape, being broader and more blunt
anteriorly and tapering posteriorly. It is usually
from 10 to 18 microns long by about 5 to 8 in width,

Fig. 24. — Trichomonas elongata.

Drawings of specimens from culture, stained by iron-haema-
toxvlon. X 1800.

but much larger forms may be seen, especially in
culture.

Its activity depends upon the material and en-
vironment of its growth. In heavy debris with little
fluid it may crawl about, twisting and turning,
elongating and shortening at will as it passes through
the avenues of its course. Its body is flexible and
plastic. In liquid medium as in fresh culture, or

160 PROTOZOAN PARASITISM

from an exudate of an active gingivitis, it is exceed-
ingly active, swimming dartingly about, with fla-
gella and undulating membrane at high speed, twist-
ing and turning, or becoming anchored caudally for
a moment, while its peripheral organelles lash and
undulate, threshing solid particles about in a violent
fashion, then pulling loose from an attenuated
anchoring appendage and swimming rapidly on its
way. Nothing more than its darting motion and its
possession of flagella and undulating membrane may
be made out of active specimens. As it slows down
from cooling or exposure the "whip-cracking" ryth-
mic lashing of flagella synchronous with the undulat-
ing membrane waves, the propulsion of bacteria
against the ingesting surface, the flexibility of the
body, the axostyle, and the revolving of the body in
forward motion may be seen.

It has four anterior flagella, which with the free
margin and the basal fiber of the undulating mem-
brane, and the stiff, posteriorly protruding axostyle,
originate from the blepharoplast, within a knobbed
anterior pole, which is the base of movement of the
motor organelles. The posterior and inner part of
the body may be seen to be vacuolated and to con-
tain granules, bacteria. The nucleus is not seen in
the unstained specimen.

Staining by Heidenhain's iron-haematoxylon
method brings out the nucleus and the structural
detail. Very pretty specimens may be made with
Wright's or Leishman's blood film stains, by care-

OF THE ALIMENTARY TRACT 161

fully developed technique, showing the several struc-
tures but no particular nuclear detail. The detail
of structure may be found recorded by Hinshaw
(1926).

As with other trichomonads of man, no cyst is
known.

To find the organism it is necessary to take mate-
rial from beneath the gums or between the teeth.
This may be mixed on a microscopic slide with 0.9%
sodium chloride solution to a dilution suitable for
good vision when examined under a cover glass. The
low dry microscopic lens reveals its presence and it
may be studied under higher powers.

Dark field examination makes a conspicuous ob-
ject of the organism, its flagella, undulating mem-
brane, blepharoplast, and food bodies standing out
as brilliant objects. When it slow^s dow^n the fla-
gella may be counted by this means, or by ordinary
high power examination when they have become very
slow or have ceased motion.

For the best stained specimens thin smears of the
exudate of its habitat are made and stained as de-
scribed under examination for amoebae.

Hinshaw (1928) produced experimental infection
of the mouths of dogs with pyorrhoea.

Hogue (1926) found the thermal death point to be
45°C.

Hinshaw (1927) found it survived suspended in
distilled water for 10 to 12 hours.

162 PROTOZOAN PARASITISM

HABITAT AND EFFECTS

Transmitted, no doubt, in the active stage by prac-
tically direct passage from person to person, such
as by kissing, possibly by the use of common drink-
ing cups, and the placing in the mouth of objects from
the mouth of another, the organism becomes seated
in the recesses of the gums and teeth. There, under
favorable conditions, it multiplies and accumulates.
The conditions for its establishment are apparently
pyorrhoea alveolaris, gingivitis, caries of the teeth,
and possibly other conditions where there is an ac-
cumulation of inflammatory exudate and debris.
Both Hogue and Hinshaw failed to find it in normal
mouths.

That is its most severe indictment. The general
conception, however, seems to be that it is a scaven-
ger, living on bacteria and possibly other foreign
materials of the accumulations in which it is found
and that it causes no harm to its host.

The fact of its presence in such a large percentage
of such conditions, and only then, makes it advisable
that it be held in mind until we know more about the
genesis of pyorrhoea and kindred diseases of the gums.

TREATMENT

Prevention of the infestation would undoubtedly
demand care to avoid taking into one's mouth any
substance contaminated with the saliva of another
and abstainence from mouth to mouth contact.

OF THE ALIMENTARY TRACT 163

Eliminative treatment would involve the clearing
up of the harbors of its life or the use of agents destruc-
tive to it.

Since both Hogue and Hinshaw found that a tem-
perature of 45 °C. was lethal to the organism it might
be practical to apply such heat for the necessary ten
minutes or so, as suggested by Rivas (1925) for treat-
ment of intestinal protozoa. Hogue notes that pro-
longed administration of neosalvarsan had no effect
upon it. The writer failed to eliminate it with eme-
tine but saw a condition of acute gingivitis rapidly
clear up and the trichomonads disappear during the
course of thorough cleansing and washing of the
gums and teeth with saturated solution of bicar-
bonate of soda.

It is probable that in deep pockets of pyorrhoea it
would be very difficult to eliminate.

No conclusions may be drawn as to any measure of
treatment at the present time, or whether it is worthy
of any treatment. Further evidence and experimen-
tation will be necessary.

TRICHOMONAS VAGINALIS

Although it is usually conceded that the vaginal
trichomonad is distinct from those of the alimentary
tract, it is necessary to consider Trichomonas vagi-
nalis here because the question is not a settled one
and it is not beyond the bounds of possibility that
they may be the same, that what differences may be

164 PROTOZOAN PARASITISM

made out are the result of environment and medium
of growth. Should either or both of the other tri-
chomonads be shown to be identical with it the species
name wdll remain Trichomojias vaginalis.

First seen by Donne in 1837, this parasite is a very
common inhabitant of the vagina, especially in the
presence of an acid leucorrhoea, although this state
may merely reveal it by calling for an examination.
It is usually found in the vault of the vagina in an
accumulation of greyish or white granular liquid
material, in which desquamated epithelium and vari-
able numbers of leucocytes are seen. Examined
fresh in this material the organism is usually larger
than either the intestinal or mouth trichomonad and
it is not as actively motile in its natural state. It is
seen crawling about in the debris and among the
desquamated cells, frequently elongating and extend-
ing a ''neck" which may be as long as the body is
ordinarily. It twists and turns upon itself and sel-
dom is of the active darting motion of Trichomonas
in a liquid stool.

In material at the bottom of a culture tube it may
have the same appearances, frequently being clumped
in colonies, attached to solid materials. In liquid
medium it develops a rapid swimming movement like
the other trichomonads.

Its variation in size is from 5 by 10 microns to 15
by 25 microns or even larger, the largest sizes being
in those preparing for or undergoing division.

It has four anterior flagella, undulating membrane,

OF THE ALIAIENTARY TRACT 165

axostyle, cytostome, nucleus, food bodies, etc., quite
similar to Trichomonas hominis and Trichomonas
elongata (buccalis), for the details of which the
reader is referred to Lynch (1922), Hegner (1925) or
Wenyon (1926).

Wenyon (1926) finds the parasite very common in

Fig. 25. — Trichomonas vaginalis.
Drawings of specimens stained by iron-haematoxylon. x 2000.

England and quotes Brumpt (1913) as obtaining
10% positive examinations in Paris. The writer has
found it very common in women with leucorrhoea and
in urine from such cases, the urine showing the or-
ganisms in centrifugalized sediment along with va-
ginal debris. It has not been seen in catheterized
urine of women. Hogue (1927) found it only once
in urine from 300 men and 333 women and then from

166 PROTOZOAN PARASITISM

fecal contamination. Dock (1894) found the or-
ganism in clumps of pus cells and epithelium in
freshly voided urine from a man on several occasions.
The writer has seen it once, in catheterized speci-
men, in the urine of a man, out of several thousand
examinations of the urine of men. Marchand ( 1894) ,
Miura (1894), and Escomel (1927), have reported it
in the urine of men. It has been cultivated by the
writer, by Reuling (1921) (according to Hogue), by
Hegner (1928), and others. The writer has secured
prolific cultures in Hogue's ovo-mucoid medium.
Hegner (1928), who has studied the spontaneous
infection of the vagina of monkeys and has cultivated
trichomonads from the monkey's intestine and vagina
and produced experimental vaginal infection with
them, makes no mention of any abnormal state associ-
ated with its presence. He finds the two morphologi-
cally similar and from this and the experimental va-
ginal infection with the intestinal trichomonad thinks
they may be the same.

Davis and Colwell (1929) consider Trichomoiias
vaginalis a very common parasite in women with ab-
normal vaginal discharges and believe it to be an
active factor in the production of vaginitis. They
cultivated it best in 5% human serum in dextrose
broth.

TRANSMISSION, HABITAT AND EFFECTS

The manner of transmission of Trichomonas va-
ginalis is unknown. Perhaps it may invade the

OF THE ALIMENTARY TRACT 167

urethra of a man during coitus. The number of such
occurrences is few enough to believe that such an ac-
cident may occur. Certainly, however, women do
not contract it in a similar way.

If it is the same as Trichomonas hominis or Tri-
chovionas elongata (buccalis) the method of infec-
tion of the vagina is obvious. This is so plausible
that it furnishes one of the strongest reasons for
suspecting this relationship.

The natural habitat is the vault of the vagina.

What harm it does there, if any, is unknown. As
with other trichomonads the question is a debated
one. The character of the material in which it fre-
quently occurs is rather characteristic. It is not pus
or mucopus, it is a greyish or whitish thick fluid
composed of epithelium, variable leucocytes and fla-
gellates. The state of the vagina may be that of a
mild catarrhal vaginitis or more marked inflammation
and there may be superficial excoriations of vaginal
wall or surface of the cervix. The excretion or exu-
date may be irritating to the vulva. The common
acid reaction of this material led the writer to make
culture media slightly acid and to treat the infection
with douches of saturated bicarbonate of soda solu-
tion. The organism has disappeared during such
treatment. Study has not been sufficient, however,
to warrant a conclusion from that.

Escomel (1917) recommends treatment with a 1 to
1000 solution of metallic iodine, freshly prepared,
or with turpentine douches.

168 PROTOZOAN PARASITISM

Mercurochrome has also been recommended.
Davis and Colwell (1929) found it lethal to the para-
site in 5% solution practically immediately. These
authors also report that liniment of soft soap from
1% to 50% strengths kills the organism instantly,
that 10% glycerine kills within one minute, that
lactic acid stops motion in 2% solution within 45
seconds, that compound iodine solution has an in-
stant killing effect in dilution of 1 to 100, mercuric
chloride in 1 to 5000 solution and compound cresol so-
lution up to 1 to 400 solution, having the same effect.
It seems that there are a variety of therapeutic agents,
which will destroy the organisms, available for va-
ginal application and that persistent treatment may
be expected to eliminate them. The fact of elim-
ination must be carefully determined.

CHAPTER XI

The Flagellates (Continued)

Chilomastix mesnili. Prevalence. Morphology. Cul-
tivation. Transmission, Habitat and Effects. Treat-
ment. Giardia intestinalis. Examination for Giardia.
Morphology. Habitat and Effects. Treatment. Tri-
cercomonas intestinalis. Enteromonas hominis. Em-
b a do monas intestinalis .

CHILOMASTIX MESNILI

Chilomastix inesnili, although a uniformly common
intestinal flagellate of man, was long confused with
other organisms, particularly with Trichomonas hom-
inis, and w^as accurately described by Wenyon only
as recently as 1910. In the past few years it has
become more familiar to the medical profession.

Reports from various regions give the incidence
of this parasite generally the greatest of all the in-
testinal flagellates. Hegner (1925) found it in 7.7%
in hospital patients in Central America, Hegner and
Payne (1921) give it an incidence of 4% in 20,000
reported cases, Boeck and Stiles (1923) found 3.2%
incidence in a survey of 8,029 persons. Jepps ( 1923)

170 PROTOZOAN PARASITISM

found it in 3.6% of 674 Tamils and in 0.6% of 350
Chinese in Malaya. Barrow (1924) found the re-
markable proportion of 535 instances of Chiloinastix
to 13 of Trichomonas and 10 of Giardia in 725 persons
who harbored intestinal protozoa in 100%. Thomas
and Baumgartner (1925) found 21 ^^ of the inmates
of a New York state school for feeble-minded women
to harbor this parasite. Smithies (1926) found it in
only 2.6% of his 3780 patients with gastro-intestinal
disturbance. Kofoid and Swezy (1920) note that it
was found in 4.2% of returned overseas soldiers, in
3.5% of soldiers who had not gone out of this coun-
try, and in 5.3% of local residents. Hill and Hill
(1927) found it in 24% of children of pre-school age
in Porto Rico.

The writer (1928) found 7.5% infection, on the
occasion of one immediate examination of purged
stool of 1040 patients having some gastro-intestinal
disturbance.

It is usually readily found, when present in active
form, by the method given for the examination of
stools. Its cysts may also be found in liquid or
natural stool in variable numbers and at irregular
intervals.

In active form, described as pearshaped, it is usu-
ally more the shape of a carrot. It is usually larger
than Trichomonas hominis but averages about 10 to
15 microns in length, although forms much smaller
and larger may be seen, especially in liquid stools or
cultures. Its shape and form is constant as compared

OF THE ALIMENTARY TRACT

171

to Trichoinonas homims, it being nonplastic, and
unflexible. Its motion is always forward, the
broader end being the head, and it distinctly rotates
as it swims. This rotation is apparently due to the
fact that the body is twisted or grooved in a spiral
from before backward.

Arising from the blepharoplast, a granule or gran-

FiG. 26. — ChilomasLix mesnili.

Drawings of trophozoite and cyst from specimens stained by
iron-haematoxvlon. x 2000.

ules just beneath the surface in the anterior extrem-
ity, are three flagella, which, in rythmic lashing, pro-
pell the body forward and brush food particles into
the cyto^tome. These can be counted in sluggish or
motionless specimens, by good lighting in ordinary

172 PROTOZOAN PARASITISM

liquid preparation, or in stained preparations. Aris-
ing also from the blepharoplast is a flagellum which
is directed backward in the cytostome and which
waves or undulates in sinuous movement, synchro-
nously with the three free flagella. The cytostome is
a distinct groove from the anterior extremity over
and into the surface of one side of the body for about
one half of its length. This groove is supported by
marginal fibers originating with the flagella.

The nucleus, not distinct, is rounded or ovoid,
in the anterior end, just beneath the surface and back
of the cytostome. In iron-haematoxylon prepara-
tions it has a definite rim, on which is irregularly
distributed chromatin, and a central karyosome.

The cytoplasm is variously vacuolated and con-
tains, usually, ingested bacteria.

The cysts were first described by Prowazek and
Werner (1914), according to Wenyon (1926). The
writer mistook them for cysts of Trichomonas hominis
(1916). They are insignificant bodies, of ''ground
glass" appearance, apt to be taken for yeasts by the
inexperienced. They are pear or lemon shaped, the
anterior end being the narrower and often elevated
by a "shoulder" above the the adjacent convexity.
They are about 7 to 10 microns in length. In iodine
preparations the nucleus and cytostome may be seen
and sometimes they may be made out in the un-
stained specimen.

Proper staining by the iron-haematoxylon method
is essential for studying the detail of these cysts.

OF THE ALIMENTARY TRACT 173

Here the nucleus, the marginal fiber and flagellum of
the cytostome, and the space between the anterior
pole and the uplifted end of the cyst shell may be
seen.

Chilomastix mesnili was first cultivated by Boeck
(1921) in a medium composed of human blood serum
one part, Locke's solution four parts, with 0.25 gram
of dextrose to each 100 cc, incubated at 37 degrees
C. in 5 cc. amounts of the medium in small test tubes.
Boeck and Drbohlav (1925) and Thomson and Rob-
ertson (1925) report its cultivation on Boeck's L. E.
S. medium, as described under Eiidamoehea histo-
lytica. The writer has grow^n it in Hogue's ovo-
mucoid medium, Boeck's L. E. S., and Tanabe's
(1925) medium for trichomonads, composed of NaCl
0.7 gram, sodium citrate 1.09 grams, LoefHer's blood
serum, dehydrated, 0.5 gram, white of egg 2 cc, dis-
tilled water 100 cc. In making this medium the
salts are first dissolved, then the egg is added and
shaken vigorously, finally the dehydrated blood serum
is shaken wdth it.

Success with these and other mediums is not al-
ways the same. As with trichomonads, bacteria are
uncontrollable and are unquestionably influential in
the success or failure in carrying on cultures.

Division of the organism is by longitudinal bi-
nary fission, such as occurs in the case of the trichom-
onads. According to Kofoid and Swezy (1920) the
nucleus divides by mitosis. Following nuclear divi-
sion occurs the splitting of the cytoplasm, the

174 PROTOZOAN PARASITISM

flagellar organelles being probably newly formed from
the divided blepharoplasts.

TRANSMISSION, HABITAT AND EFFECTS

That Chiloviastix mesyiili becomes readily trans-
mitted is shown by its widespread relatively high
prevalence. Once looked upon as a tropical parasite,
and possibly still to be regarded as of higher incidence
in warm regions where sanitation is poor, it is able
to survive more rigorous climates and to spread in
disregard of modern sanitary facilities. The increase
shown by Thomas and Baumgartner in institutional
life indicates person to person passage, no doubt by
unclean personal hygiene and the handling of food
by carriers with unclean hands.

The fact that it has a cyst indicates this as the
resistant and transmissible phase but it is not cer-
tain that the trophozoite may not pass to establish-
ment in a new host, even through the stomach, in
naked form. Experimentally it has stood exposure
to hydrochloric acid even better than has Trichom-
07ias hommis, which is believed to necessarily pass
the stomach in active form. It withstood 0.1%
and 0.2% solutions of the acid in 0.9% sodium
chloride solution and was active after IVo hours, but
not in 0.3%. The active forms are almost immedi-
ately destroyed by water and they probably are not
transmitted in that medium, although the cysts may
be.

OF THE ALIMENTARY TRACT 175

In addition to the transmission of the parasite
from personal contact, the spread of the cysts from
exposed excreta by flies no doubt takes place.

The writer (1928) found Chilomastix mesnili to
be more related to city life, 80% of its hosts in his
study being city dwellers as compared to 56% of
Trichomonas carriers and to 70% of the flagellate-
free. Males wTre a bit more frequently infected;
in a clientele of about 60 females to 40 males, 51%
of Chilomastix hosts w^ere males. Perhaps men come
more into contact with it by being in contact with
more people.

As the age of indivickials increases so does the
frequency of the parasite, only 11% of Chilomastix
carriers were below forty years of age and 55% be-
low fifty, w^hile of Trichomonas carriers 53% were
below forty and 83% below^ sixty. This is consistent
with the finding of Thomas and Baumgartner. The
organism seems comparatively tenacious as a parasite.
Although it varies in numbers from time to time it
seems to maintain itself in the intestine for long or
indefinite periods. One host is known to have har-
bored it for a period of fourteen years.

Of the Chilomastix carriers 40% showed a condition
of gastric anacidity, w^hile this was the case in but
19% of the flagellate-free. On the other hand, only
10% of them had an excess of gastric hydrochloric
acid at the time of examination, in contrast to 25%
of the free.

There was diarrhoea at the time of examination

176 PROTOZOAN PARASITISM

or conspicuous in the history in 8% of the flagellate-
free and 6% of those with Chiloinastix, while con-
stipation was the state of 74% of the parasitized,
against 55% of the free.

Although recognized as an indefinite thing in it-
self, there was a clinical diagnosis of chronic chole-
cystitis in 37% of the carriers of Chilomastix, as
compared to 22% of the non-parasitized.

There was undoubtedly a state, in patients of the
later years of life, in which there was gastro-intes-
tinal disturbance, but of no definite character, with
achlorhydria and constipation as conspicuous fea-
tures and in which chronic cholecystitis was com-
monly diagnosed, in which the presence of Chilo-
mastix ynesnili was an outstanding finding. In none,
however, was the organism found in gastric, duodenal,
or transduodenal biliary drainage.

Since this is the sort of clinical state in which the
organism has been under suspicion by medical prac-
titioners, these findings must be held in consideration
for further information. The question is, which is
the cause and which the effect. Is the prominence
of the organism here because of the favorable condi-
tions for it, later life, a lowered acid barrier in the
stomach, a fertile field for its maintenance in a stag-
nant intestine content, or is the organism related
directly or indirectly to the development of this ab-
normal state?

There were no other symptoms, signs or labo-
ratory evidences of disturbances related in any way

OF THE ALOIENTARY TRACT 177

to the presence of the organism, beyond the control
group.

It should be recorded that none of these Chilo-
mastix hosts suffered from arthritis deformans, since
Barrow (1924) found 94% of 79 cases of this disease
to harbor this parasite.

The natural habitat of Chilomastix mesiiili is the
colon, particularly the caecum. There it lives only
as a lumen dweller, so far as is known. Wenyon
(1926) found it in the lumen of the glands of the
colon. It has not been observed as a tissue invader.

It is not known to cause any local degenerative or
inflammatory change and the conjectured pathologic
state produced by it is virtually narrowed down to a
state of ''toxemia," of which there is only circum-
stantial evidence.

Castex and Green way (1925) are among the latest
to promote such a role for the organism, they finding
it in 118 of 614 cases of "chronic intestinal toxemia,"
in which they were of the opinion that the organism
was the pathogenic factor and essential cause of the
different toxic symptoms in the 49 cases of ''pure
infection."

TREATMENT

Preventive. Since Chilomastix mesnili thrives in
spite of modern sanitary precautions against the
spread of infection, it is to be suspected that person to
person transmission is the important method in mod-
ern civilized communities. More careful observance

178 PROTOZOAN PARASITISM

of rules of personal hygiene and, probably, the con-
trol of food handlers which harbor the parasite, seem,
therefore, to be of particular importance in any ex-
pectancy of prevention of its spread. Proper sewage
disposal and fly control are already well observed
where it is prevalent, but no doubt are responsible
factors in the spread of the parasite and for higher
incidence in regions where these practices are not in
force. Control of the spread of this parasite seems
to be quite similar to that of Endamoeba histolytica.

Curative. There is nothing in the nature of a
specific curative method of treatment or drug to be
presented in this case.

The several remedies which are used against the
intestinal trichomonad are used against Chilomastix.
Among these the arsenicals have been used. In the
test tube, however, neoarsphenamine in as strong
solution as 0.45 gm. per 100 cc. of 0.9% sodium chlo-
ride solution did not kill this organism within an hour.

It should not be difficult to determine the effect
to those arsenicals used in the treatment of syphilis,
since a certain per cent, of the patients of any syph-
ilis clinic harbor the parasite, and it is not difficult to
determine its presence and continuance.

GIARDIA INTESTINALIS. (GIARDIA LAMBLIA.
GIARDIA ENTERICA.)

Giardia intestinalis, formerly called Lamhlia in-
testinalis, is the representative in man of a genus
of protozoa having a number of species in animal

OF THE ALIMENTARY TRACT 179

hosts. As pointed out by Dobell ( 1920) it was prob-
ably first seen by Leeuwenhoek, the father of Proto-
zoology (1681), who found himself to be a host of it.

Lambl in 1859 and 1860, Grassi (1879), and Blan-
chard (1888) are the early students concerned with
its history.

Until the past few years it was thought to be an
uncommon parasite and there was little study of it
except an occasional report of its presence in some
person, usually a child, who had diarrhoea.

Of late, it has come into more general recognition
as a very common intestinal flagellate, especially in
children.

Kofoid, Kornhauser and Plate (1919), in one of the
earliest studies of a large number of persons, found
1500 United States soldiers, 300 of whom had not
seen foreign service, to harbor it in 6% . Hegner and
Payne (1921) arrived at an average incidence in
20,000 reported cases of 12%. Boeck and Stiles
(1923) give an incidence of 6.5% in 8029 persons,
many of whom were children, examined by them.
Thomas and Baumgartner (1925) found only 2.5%o
incidence in female institutional inmates. Maxcy
(1921) found about 20% of 74 children between one
and thirteen years of age infested. In England, Mat-
thews and Smith (1921) found 14% of 548 children,
Campbell (1921) found 16% of children under twelve
years, and Nutt (1921) found 48.8% of institutional
children and 23.9% of hospitalized children, to har-
bor the parasite.

180 PROTOZOAN PARASITISM

In Porto-Rican children of pre-school age Hill and
Hill (1927) found an incidence of 47.2%. The writer
(1928) found an incidence of only 2.3% in a medical
clientele of 1040 cases, in which, however, children
were a small part of the number, and, even at that,
45% of the Giardia hosts were under twenty years of
age.

It was long believed that Giardia infection of man
was derived from other animals. At the present
time there is no reason to suppose such to be the
case, nor is there need to go outside humankind to
find sufficient explanation of the source of the para-
site. While many animals harbor giardias indistin-
guishable from that of man by the inexperienced, and
some have species very closely similar at expert obser-
vation, it is generally considered by the best authori-
ties that they are distinct species and that ordinarily
the only one with which man is concerned is his own.

Institutional studies indicate that transmission is
commonly by almost direct transfer from one person
to another. Close personal contact with the infected
leads to spread of the parasite regardless of modern
sanitary precautions as to the disposal of sewage, fly
control, etc. Undoubtedly, however, the contamina-
tion of food and drink by food handlers of unclean
habits, the exposure of human excreta, without disin-
fection, to flies, and to drinking water, the use of
human feces as fertilizer for garden stuffs, are all
capable of and probably do play their part in trans-
mitting the organism.

OF THE ALIMENTARY TRACT 181

As with most of the intestinal protozoa the cyst
is the transmissible form. The trophozoite does not
appear in the natural stool and even when passed
from the intestine, as in diarrhoea, it is so delicate
that it does not live long and is apparently incapable
of surviving exposure to the acid of the stomach for
a sufficient period to allow it to pass alive to the duo-
denum.

It has been observed in stomach contents when
there was no trace of free hydrochloric acid, but was
almost immediately destroyed by gastric juice of nor-
mal acidity and by 0.1% hydrochloric acid in 0.9%
sodium chloride solution. Although it is not impos-
sible that some of the other encysting protozoa of
man's intestine may pass in viable trophozoite form
through the stomach at times, Giardia intestinalis
apparently never does.

EXAMINATION FOR GIARDIA

The routine stool examination practice given un-
der the amoebae is sufficient for determining the pres-
ence of Giardia intestinalis when it is appearing in
stools. When there is diarrhoea it is usually present
in active form, and a late specimen following a saline
purgative will usually bring it out in this form.
Otherwise it is only the cysts which appear and they
irregularly or periodically, so that it is difficult to be
certain- that it is not present from even several ex-
aminations. In this case, except in liquid stool, it

182 PROTOZOAN PARASITISM

is the cyst which must be depended upon for appear-
ance.

In case of their presence, duodenal or trans-duo-
denal biliary drainage usually shows the trophozoites,
not the cysts, in the duodenal content removed. The
parasite became very prominent in the course of
the recent commonly practiced trans-duodenal bili-
ary drainage. The writer has seen it frequently in
such material. Hollander (1923) found it in nine
of one hundred and seventy such examinations. This
is, however, not necessary as a measure for this pur-
pose only.

The trophozoite has a form so characteristic that
it should take only a picture of it to lead to identifi-
cation on first observation. If a pear were split in
halves longitudinally and inverted and the anterior
half of the split surface scooped out to a shallow con-
cavity, one would have the form of an inert organism.
Assume that body as flexible and attach at the proper
places four pairs of long flagella, which in movement
cause the organism to vibrate rapidly as it swims and
flexes its body, and one has the form and action of the
organism.

The size of the active form is about 10 to 20 microns
long by about half that width. Seen anteropos-
teriorly it is pearshaped. In lateral view the dor-
sal surface is convex forward and concave behind, the
outline being a shallow S, while the ventral side shows
the forward depression of the oral sucker, and a grad-
ual tapering from its border to the tail, this in the

OF THE ALHIENTARY TRACT 183

motionless organism. In that state the flagella may
be seen to hang as long delicate fibrils, one pair from
forward on the outer border of the sucker, two pairs
from near the midline posterior to the sucker, and the
fourth pair from the tail.

In motion the body vibrates rapidly with the ac-
tion of the flagella and it frequently doubles upon

Fig. 27. — Giardia iritestinalis.

Trophozoite and cyst as drawn from living unstained specimens.
X 2000.

itself. After all other motion has ceased, the fla-
gella which extend backwards along the ventral mid-
line may continue to undulate.

In fresh unstained specimens the cysts are readily
recognizable to one on the search for them, although
they vary in number in the same individual and may
be absent at times. There is some belief that they
appear periodically as a habit of life of the organism.

184 PROTOZOAN PARASITISM

They are about 8 to 15 microns long, are of an
elongated ovoid shape with rather bluntly rounded
ends, and are of a "ground-glass" appearance. In
one end are the nuclei which may be seen on careful
observation, reminding one of eyes. In iodine solu-
tion, showing the cyst wall, the brown body, with
the nuclei and the flagellar apparatus more or less
distinct, the cyst can hardly be confused with any-
thing else. Uniformly sized ovoid "ground-glass"
bodies with "eyes" in one end are likely to be Giardia
cysts.

In preparations stained with the iron-haematoxy-
lon method, specimens showing rather clearly the
intricate flagellar system, the nuclei, the cytostome,
the axostyles, are obtained without great diffi-
culty.

The oral sucker is composed of two discs or shield?,
outlined by stiff marginal fibers. There are two nu-
clei in the cytoplasm, one about the middle of each
shield, each with central karyosome. The anterior
pair of flagella arise from the blepharoplasts and af-
ter passing forward for a way, decussate and round
the margins of the oral sucker, becoming free after
traversing about one third of the margin. The two
middle pairs of flagella come from about the junction
of the two lateral shields posteriorly, one pair pass-
ing directly backward, the other diverging. The two
posterior flagella are the free fibrils, coming from
that extremity of two stiff fibers, the axostyles, pass-
ing straight up the middle of the body to the blepharo-

OF THE ALIMENTARY TRACT

185

Fig. 28. — Giardia intestinalis.

A and B, trophozoites as seen from lateral and anterior view.
C, D and E, cysts in different stages of development. Drawings of
specimens stained by iron-haematoxylon. x 2000.

plasts. A ''parabasal" body occupies an oblique po-
sition in the cytoplasm posterior to the junction of
the shields. In the cyst the stage of development
determines the number and position of the nuclei
and the neuro-motor apparatus. The oral sucker
is not seen although some of the marginal fibers of
the two shields may show. The nuclei may be tw^o,

186 PROTOZOAN PARASITISM

in one end of the cyst, in the single organism, but
commonly are four in number, usually all grouped
but at times two in one end and two in or toward the
other. The fibrils of the flagellar apparatus are
twisted and wavy lines, to be studied by the very care-
ful investigator. The cyst is, therefore, a multiplica-
tion cyst as well as a resistant phase. It is readily
stainable and its structure recognizable. For more
minute structural detail the reader is referred to
works, such as by Wenyon (1926), dealing more at
length and minutely with such matters than is here
desirable.

The organism divides within the cyst, by binary
fission, after mitosis of the nuclei, and two offspring
are liberated at excystment, on reaching its natural
habitat. Similar longitudinal division has been de-
scribed in the active form and this probably occurs
within the intestine, since excystment in the same
individual does not seem likely. Under conditions
of observation of the parasite from duodenal con-
tents and liquid stools division is not apt to be seen.
Cultivation of the organism has not been done
and its reproduction has not been extensively fol-
lowed.

The cytoplasm is of alveolated, finely granular
character, the dorsal part more dense than the ventral.
It is not vacuolated or filled with bacteria as in the
other flagellates. Evidently its food is taken in solu-
ble form and the materials have not yet been supplied
properly for the growth in culture.

OF THE ALniENTARY TRACT 187

HABITAT AND EFFECTS

The home of Giardia intestmalis is the upper small
intestine, apparently mainly the duodenum, instead
of the caecum as with Trichomonas and Chiloviastix.
Here the organism finds the environment and mate-
rials suited to its well being and multiplication. That
its needs are radically different from those of other
flagellates is given evidence by its structure, the
absence of bacteria from its body, and its failure to
survive in media which will grow others well. As
it passes down the intestine it becomes encysted and
prepares for transference to a new host in mutiplied
form.

It is believed that the oral sucker is the means of
maintaining its position and it has been seen at-
tached by this apparatus to the epithelial surface
of the mucosa. It has not been ascertained that it
damages these cells or excites any reaction on the
part of the mucosa, although some believe that it
irritates the epithelium and stimulates mucus produc-
tion.

The term '^giardiasis" has, at the present time,
no definite meaning beyond the presence of the para-
site in the intestine. In children Giardia has been
suspected of an etiologic role in persistent diarrhoea,
with clear or yellowish mucus, in which are seen large
numbers of the active form of the organism, con-
spicuous in the stool.

Hill and Hill (1927) in a survey of children of pre-

188 PROTOZOAN PARASITISM

school age found that of the 47.2% infected with
Giardia intestinalis, 57.6% had chronic or recurring
diarrhoea, as compared to a similar history in only
24.2% of the flagellate-free, and in M.^% and 27.9%o
of the carriers of Chilomastix viesnili and Trichom-
onas hoinmis, respectively.

Zahorsky (1928) is convinced of the production of
intestinal disturbance in children.

The very common occurrence in children, especially
under crowded conditions, without any evidence of
the production of any disturbance, brings serious
question as to whether it ever causes trouble. It is
most common between the ages of one and ten years
and this is the period when intestinal upsets are most
apt to occur. Merely its presence in a case of diar-
rhoea or dysentery does not prove it to be a patho-
genic factor.

There is, however, a very strong belief in the medi-
cal profession that giardiasis signifies a state of up-
per small intestine irritation with ''indigestion" and
chronic or recurring diarrhoea, with mucous, but
never bloody, stool, occurring particularly in young
children. Such studies as that of Hill and Hill (1927)
showing diarrhoea conspicuous, much beyond the con-
trols, is strong evidence in support of this belief.
Similar repeated studies with like results would go
far toward establishing the pathogenicity of the or-
ganism in a definite clinical syndrome. From a
working viewpoint it is, perhaps, not unwise or un-
reasonable to assume that such a condition occurs,

OF THE ALIMENTARY TRACT 189

unless it is more clearly shown that such is not the
case.

As to the infestation of the biliary tract and gall-
bladder there is further suspicion, and need of further
investigation. The presence of the organism in the
bile and duodenal material from a trans-duodenal
biliary drainage does not prove that it came from the
biliary system. However, it has been observed, ac-
cording to report, within the gallbladder, removed by
operation, on several different occasions, and it is
believed by some that it is related to a state of
chronic biliary tract inflammation with jaundice,
this state associated with later life and a sluggish or
costive bowel.

In the writer's experience it occurs in the young
and the old, 27% of the Giardia hosts, all being chil-
dren, having diarrhoea, as compared to 8% of the fla-
gellate-free, 6% of the carriers of Trichomonas hom-
inis and 7% of carriers of Chilomastix mesnili, while
40%, these all being adults, were constipated.

TREATMENT

In a general way the prevention of this infection
should follow the same rules as for Eiidamoeba histo-
lytica or Chilomastix mesnili. Although, no doubt,
commonly transferred in the encysted stage by ex-
posure of unsterilized human excreta to drinking
water atid to flies, and the use of it in garden stuff
fertilization, in modern community life and in in-

190 PROTOZOAN PARASITISM

stitutions where these conditions are controlled it
still thrives and is readily transferred by direct con-
tact, unclean personal habits, direct finger to mouth
transmission, and the contamination of food by its
handlers.

The ways and means of prevention of its spread
are obvious, although no doubt difficult of enforce-
ment under crowded conditions, particularly in a
certain type of institution for boarding homeless chil-
dren.

Although generally believed, it is not definitely
show^n that some of our domesticated animals and
pets may not carry giardias transmissible to man.
If it should be the case that some infections may be
of this source, the ^^dirty" age of childhood, particu-
larly, would need to be protected against this possi-
bility.

Specific eliminative treatment has proven largely
unsatisfactory to the present.

It should be borne in mind that its absence from
the intestine is not provable by single or even a re-
peated examination, and that a supposed elimination
may not be real. Prolonged observation is necessary.

Various drugs have been reported as efficacious by
some and as of no effect by others. Among these
are quinine, emetine, bismuth subnitrate, beta-naph-
thol, methylene blue, and the salvarsans.

Zahorsky and McLoon (1927) recommend bismuth
salicylate, given in 5 grain (0.3 gram) doses three
times a day to a child of six years.

OF THE ALIMENTARY TRACT 191

Hollander (1923) after failing to effect the presence
of the organism with arsphenamine injected in the
usual way at 3 to 5 day intervals, alternated these in-
jections with duodenal lavage with magnesium sul-
phate solution in one case, the patient remaining free
of the parasite to examination of duodenal contents
over a period of six months.

Kofoid (1919) et al., freed rats of their natural
infection by giving arsenobenzol in one intravenous
injection of four to eight times the ordinary human
dose, pro-rated by weight, the rat successfully stand-
ing the treatment.

At the present time eliminative therapeutics is in
an uncertain and experimental stage.

On this account and because of the uncertainty as
to the necessity for treating it at all, ill advised thera-
peusis should be avoided and any measures used in
the cases of young children should be very thought-
fully regarded first.

TRICERCOMONAS INTESTINALIS

In addition to the more common and larger intes-
tinal flagellates, man harbors several less common and
smaller forms.

Among these is Tricercovionas intestinalis (Wen-
yon and O'Connor, 1917), found in widely separated
regions but apparently of comparatively rare occur-
rence. 'It is subject to the likelihood of confusion
with other small flagellates but the description of

192 PROTOZOAN PARASITISM

Wenyon and O'Connor has been confirmed by the
writer (1922). It has also been observed in this
country by Boeck (1924).

The organism is from 4 to 7 or 8 microns in long-
est diameter, it being almost rounded or slightly
ovoid. It is very active in fresh preparation, swim-
ming jerkily and rotating at the same time. The
cytoplasm is alveolated and contains bacteria. It
anchors itself by a caudal process, as is the habit of
flagellates when feeding.

The anteriorly directed fiagella move rapidly and
are not to be counted with certainty in an active
stage. At times they can be seen to come from a
minute knob, the blepharoplast. There is a re-
current flagellum which arises at the same place
passing posteriorly over the surface of the body, to
which it is adherent for about three fourths of the
body length, terminating in a free extremity from
the posterior quarter. In motion there is a slight
protoplasmic projection where this flagellum leaves
the body. The nucleus is not visible in the unstained.
The cysts are minute bodies, slightly smaller than
the trophozoite, and possess a nucleus in each end,
as seen in stained specimens. They are ovoid in
shape and have a definite cyst wall.

In preparations stained by Wright's blood film
stain the fiagella could be observed and counted. In
iron-haematoxylon preparations the nucleus was
seen at the base of the fiagella. It was ovoid and
had a central karyosome and definite rim.

OF THE ALIMENTARY TRACT

193

The organism grew well for four days in ascitic
fluid diluted with 4 parts of 0.9% sodium chloride
solution, ranging in size from 3 microns to 10 mi-
crons in the dividing forms. Division was by longi-
tudinal fission, the nucleus apparently passing

Fig. 29. — Triccrcomonas and Enteromonas.

A, B, C and D, trophozoites, E, cyst, of Tricercomonas intesti-
nalis. F, G, H and /, Enteromonas from the guinea pig. C, D
and /, dividing forms. Drawings from specimens stained by iron-
haematoxylon. x 1600.

through mitosis, the two halves of the dividing body
being equipped with nucleus and flagella before the
body completed division.

The parasite has been cultivated in Boeck's L.
E. A. medium by Boeck (1924) and Thomson and
Robertson (1925).

194 PROTOZOAN PARASITISM

The writer did not find it in duodenal drainage of
the host and assumes it to be a large intestine in-
habitant.

Nothing further is known at the present in regard
to its life history or relation to its host.

ENTEROMONAS HOMINIS

Subject to confusion with Tricercomonas intes-
tinalis and with Emhadomonas mtestinalis as a small
flagellate, named Enteromonas hominis by Da Fon-
seca (1915).

The size, motion, shape and nucleus are quite simi-
lar to Tricercomonas intestinalis but there appear to
be only two anteriorly directed flagella and the recur-
rent one does not appear to be definitely fixed into
the body.

Similar organisms have been seen by several ob-
servers in widely separated regions. The writer
(1922) observed what was apparently a species in the
guinea pig and named it Eiiteromojias caviae.

EMBADOMONAS INTESTINALIS

Of better standing and wide distribution, though
not as common as the larger flagellates, is another
minute organism, Emhadojnonas intestinalis, found
by Wenyon and O'Connor (1917) in Egypt. It has
been seen and described by Kofoid, Kornhauser and
Plate (1919) and by Hogue (1921) in this country,
the latter investigator cultivating it in several media.

OF THE ALIMENTARY TRACT 195

The organism measures about 5 to 7 microns in
length, is pearshaped, has a conspicuous cytostome
and two flagella, the anterior of which is directed for-
ward and used in locomotion, the other directed back
through the cytostome and apparently used in feed-
ing. It moves in a jerky manner.

The cytoplasm is alveolated and vacuolated and

Fig. 30. — Emhadomonas intestinalis.

Drawings of trophozoite and cyst from specimens stained by
iron-haematoxylon. x 3800.

contains bacteria. The nucleus, seen only in iron-
haematoxylon stained specimens, is at the base of
the flagella, is rounded, with definite membrane and
central karyosome.

The cysts are slightly smaller than the tropho-
zoite, are pearshaped refractive bodies, resembling
the cysts of Chilomastix viesnili, but smaller.

Although attention has been called to the organ-
ism usually in conditions of diarrhoea, there is no
definite information as to its exact habitat in the in-
testine or any local or systemic effect of it.

CHAPTER XII

The Ciliates

Classification, General Characteristics. Balantidium
coll. Prevalence. Transmission. Morphology. Habi-
tatat and Effects. Balantidial Dysentery. Chronic
Balantidiosis. Treatment. Balantidium minutum. Nyc-
totherus baba.

class: ciliata.

order: heterotrichida.
genus: balantidium.

species: B. coli.

B. minutum.

GENUS : NYCTOTHERUS.

species: A^. baba.

THE CILIATES (CILIATA)

Of the class of Protozoa known as the Ciliata, com-
monly called the Infusoria, there are two genera
with representatives in man's alimentary tract : Bal-
antidium, represented by B. coli and B. minutum,
and Nyctotherus, represented by N. baba. There
are other species described but not well accepted.

The Ciliata are characterized by rather large size,
complete surface covering of short filamentous or

196

OF THE ALniEXTARY TRACT 197

hairlike processes, called cilia, a prominent mouth,
contractile vacuoles, and two nuclei, the macronu-
cleus or meganucleus, the larger, having to do with
the somatic life of the organism, the micronucleus
concerned in germination.

The cilia are set in the ectoplasm of the body,
through the surface, in rows. Their movement is
rythmical and reminds one of a grain field with wind
waves. Except those of the cytostome area they
are purely for the purpose of locomotion, serving to
propel the organism rapidly forward and at the same
time rotating it slowly, by means of the creation of
currents.

The cilia in the depression around the cytostome
are longer and serve for food gathering and introduc-
tion into the mouth.

The mouth or cytostome is conspicuous as a fun-
nel-like indentation in one surface, the ventral, and
from it food particles are carried into the endoplasm
through a short oesophagus.

The ectoplasm is more dense than the endoplasm,
which is vacuolated, the vacuoles serving as stom-
achs for the digestion of bacteria and other food mate-
rials.

The contractile vacuoles, seen only in this class
of alimentary tract protozoa, are present in many
free-living forms of protozoa. They pulsate ryth-
mically and are related to the circulation or metab-
olism of the organism.

At the posterior end of the body is a small indenta-

198 PROTOZOAN PARASITISM

tion, the excretory pore, through which the waste
products are cast out.

The macronucleus, the large somatic nucleus, lies
deep in the central part of the body, is bean shaped,
and close to it, in the depression, lies the small micro-
nucleus.

The whole body of the organism is somewhat pear-
shaped, the smaller end being anterior. It is of
fairly constant shape but is somewhat plastic and may
show some degree of flexion and elongation in forc-
ing its way through compact solid materials.

Those who have httle or no opportunity to study
these parasitic organisms, will be able to familiarize
themselves with the general form and thereby avoid
confusion with the flagellates by studying the com-
mon free living kin, Paravieciuin, in pond water or
grass infusion.

BALANTIDIUM COLI

The most common cihate of man's intestine, and
the most conspicuous in size, is Balaiitidiuin coli,
discovered by Malmsten in 1856 in two patients with
dysentery in Stockholm. This is the only one fa-
miliar, even by name, to any considerable number of
physicians or medical laboratorians.

At that it is not a common parasite. While it
has been reported of world wide distribution, and is,
by Walker's (1913) report, relatively common in the
Philippine Islands, it is a rare parasite of man in this
country. Craig notes that it has been seen in man

OF THE ALIMENTARY TRACT 199

in Arkansas, California, Iowa, Louisiana, Minne-
sota, North Carolina, New York, and Oklahoma, and
that, although he has done many thousand examina-
tions of stools, he has encountered the organisms
only a half dozen times and never in any individual
examined in the United States. Deeks (1925) notes
its presence in hospital laboratory reports in central
America, in 13 cases in 1923, 88 cases in 1924, and
128 cases for 1925, while Aguilar (1925) reports that
during the period from August 30th to October 2nd,
inclusive, 40 cases of balantidic infection were ad-
mitted to the Quirigua Hospital, Gautemala, this
being 10% of the admissions. All of these patients
were apparently admitted on account of some other
ailment, all gave a questionable history of diarrhoea,
and fourteen of them showed pus or pus and blood
in the stool. He believes that balantidial infection
is most prevalent in this region following the rainy
season and that its source is the common domestic
pig. In the Annual Report of the United Fruit Co.
for 1928, J. C. McDaniel, reports finding B. coli in
0.41% of 5587 stool examinations. The only in-
stance of its occurrence in man in this country ob-
served by the writer w^as in an Arabian immigrant.
Balantidium coli is a fairly common intestinal
parasite of the domestic pig and it is believed by
many that this animal is the natural host, that man
is a host by accidental transmission from the pig.
It is highly probable that the isolated cases of infec-
tion of man are from this source and entirely likely

200

PROTOZOAN PARASITISM

that the pig is the main source of spread. It is also
a parasite of the intestine of monkeys.

It is transferred in the encysted phase from the
feces of swine, probably of man, and possibly of mon-
keys, to man by ingestion of contaminated sub-
stances or, perhaps, directly from hand to mouth.

Fig. 31. — Balanfidium coli.

Drawings of trophozoite and cj'st from specimens stained by iron-
haematoxylon. x 550.

Balantidium coli is a large organism, by compari-
son to other alimentary tract protozoa, the original
description of Malmsten giving it a size of 60 to 100
microns long by 50 to 70 microns wide, small and large
forms occurring in individual infections, according
to Craig (1926).

It is roughly pearshaped, the narrower end being

OF THE ALIMENTARY TRACT 201

the head. The surface is entirely covered by diago-
nally longitudinal rows of fine cilia arising in grooves
in the ectoplasm. To one side of the anterior end is
a funnel-like depression, the peristome, leading into
the cytostome or mouth. The peristome is lined by
longer and more delicate cilia. These gather food
and by selection, or "taste" as Dobell (1921) ex-
presses it, pass on the desirable to be ingested through
the cytostome and short tubal gullet into the endo-
plasm, where it is digested in the vacuole stomachs.
The food consists of a variety of substances from the
intestinal contents and tissues of its habitat, the rec-
ognizable bodies being bacteria, starch granules, red
blood corpuscles, leucocytes and tissue fragments.

The cytoplasm is mainly granular, alveolated and
vacuolated endoplasm, wdth a thin clear zone of ecto-
plasm beneath a membranous pellicle.

The contractile vacuoles are tw^o in number, one
in the dorsal region, slightly anterior, the other near
the posterior end. They pulsate slowly and ryth-
mically and are not easily made out at all times. The
excretory pore is a small oblique aperture in the ter-
minal end.

The macronucleus, a large body of kidney-like or
sausage-like shape, lies near the middle of the body
and in its bend is the minute micronucleus. In
stained specimens the chromatin of the macronu-
cleus is a mass of compact granules. The micronu-
cleus may be so closely in contact with the larger
nucleus as to be obscured.

202 PROTOZOAN PARASITISM

The motility of the organism is free swimming for-
ward with slow rotation, the locomotive cilia waving
rapidly and rythmically, the organism remaining of
constant shape, although it is plastic and may flex
and elongate in pushing its way through compact
debris.

Multiplication is by transverse binary fission, the
micronucleus dividing by mitosis, the meganucleus
amitotically (Dobell, 1921), the cytoplasm constrict-
ing transversely and forming two offspring, the pos-
terior one necessarily forming new anterior parts
and both undergoing more or less reorganiza-
tion. It has been cultivated by Barret and Yar-
borough (1921) in a medium composed of 1 part
of inactivated liquid human blood serum to 16
parts of 0.5% sodium chloride solution, incubated
at 37"C.

The cyst, formed as the organism passes down the
colon, is more rounded or ovoid, and has a definite
wall. The body loses its food bodies and vacuoles
and becomes compact and granular. It shows more
or less cilia and other characteristic features in the
newly formed cyst, in fact it still revolves for a short
time within the thickwalled space. Older cysts may
show only the shell, the body, and macronucleus of
the organism. The cyst measures 45 to 65 microns.
It survives exposure for some time outside the body
in a moist state.

The active form may usually be seen at any time
in feces of the infected, varying in number and ac-

OF THE ALIMENTARY TRACT 203

tivity, being more conspicuous in diarrhoea or dysen-
tery. The cyst is not always present, even in the
natural stool.

Both are subject to ready observation and identi-
fication in fresh unstained preparation, the structural
detail being subject to complete study only in well
stained specimens, such as from the iron-haematoxy-
lon staining.

The inexperienced should have no difficulty in
recognizing it in stool examination; a knowledge of
the existence of such an organism, a picture of it,
and observation of it in fresh stool, should be all that
is necessary. One should beware, however, of the
common occurrence of similar free living forms which
may occur in stale stools or in stagnant solutions.

HABITAT AND EFFECTS

Balantidium coli occurs as a parasite of the colon
of man, after it has hatched from ingested cysts. Its
activity is mainly in the caecum and it naturally en-
cysts as it passes down the intestine. It may be seen
active in any part, however, of the colon.

The behavior of the organism and its effects upon
the host are not unlike the case of Endamoeba histo-
lytica. It is a parasite therefore of considerable in-
terest in medicine, and balantidiosis of the intes-
tine of man has a significance akin to intestinal
amoebiasis. In fact the different phases of intestinal
amoebiasis have their counterparts in intestinal bal-

204 PROTOZOAN PARASITISM

antidiosis; there are the two states, chronic balan-
tidiosis and acute balantidial dysentery.

BALANTIDIAL DYSENTERY

The acute phase of the disease is the unusual con-
sequence of infection, the acute attack, or the end
result.

In this condition the organism is known to be a
tissue invader. Manlove (1917) records that bal-
antidiosis is a relatively unimportant cause of death
in the Philippines, but may cause considerable mor-
bidity, being characterized by colitis varying from
simple catarrh to deep ulceration. Strong (1904)
reviewed 127 cases in the literature of that time,
wdth 35 deaths and 32 autopsies, including one of his
own, of which 28 showed ulcerative colitis and 3
chronic catarrhal colitis. Walker (1913) produced
experimental infection of monkeys with the organ-
ism from man and pigs and studied the evolution of
the experimental disease.

He found that Balantidiuvi coll does not enter
through the lesions of colitis of other causes but
through the sound intestinal epithelium, becoming
the primary etiologic factor in balantidial dysentery.
The early lesions consisted of hyperemia with or
without punctiform hemorrhages, showing histo-
logically, vascular dilation, minute hemorrhages,
round-cell infiltration and eosinophilia. Some of the
later submucosal abscesses were bacteriologically

OF THE ALIMENTARY TRACT 205

sterile. The epithelium in early infection was intact
except for mechanical injury, attributed to the en-
trance of balantidia or to minute hemorrhages, there
being no exudation or ulceration.

Strong found the organisms invading the mucosa,

., *

-'«*.„

*

%

X

• .^

fc«r . • ^

.^~

r-^'

¥?

« ,.

-•. •- ^ .,* "

♦ %. "

, ;

""*

*».*

'*i

. ■ ^ ' •-■ .«

,,1'q^''

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A

Fig. 32. — Balantidial Colitis.

Group of Balanlidium coli in the tissues of the submucosa below
ulcer of the mucosa of the colon. Photomicrograph x 43.

submucosa and muscular layers. They were less
numerous in the necrotic areas and were found in
the margins of healthy tissue around these areas.
The capillaries of the mucosa and submucosa were di-
lated, contained balantidia, and often showed hem-
orrhage. The amount of infiltration was small about

206

PROTOZOAN PARASITISM

single parasites in the tissues, but was well marked
around collections of the organisms. The ulcera-
tions were undermined and often extended to the

Fig. 33.

Balanlidium coli within the tissues of the siibmucosa of the
ulcerated colon in balantidial dysentery. Photomicrograph x 475.

muscular coat. The lymph nodes were hyperemic
and enlarged. No parasites were found in any tis-
sues outside the large intestine.

From these and other investigators it may be de-
termined that Balantidiwn coli is capable of primary

OF THE ALIMENTARY TRACT 207

penetration of a normal epithelial surface of the
colon and of traveling in the tissues below. It ex-
cites a reaction of an inflammatory nature, includ-
ing hyperemia and mononucleosis, although some
record eosinophilia. Hemorrhage and necrosis oc-
cur, with the production of necrotic abscesses of the
submucosa, w^hich open through the mucosa to the
surface, producing an undermined or flask shaped
ulcer. The organisms may be seen singly, wander-
ing afield from these primary foci, exciting little ap-
parent reaction except as they accumulate. They
occur in tissue spaces, the lymphoid follicles, lymph
and blood vessels. As they multiply the abscesses
and ulcers are extended and may become large and
deep, even into the muscle coats, remaining, like
amoebic ulcers, undermined, ragged, bowl-shaped.
The manner of tissue destruction is not proven.
Glaessner (1908) extracted a haemolysin but no
proteolytic ferment. It is not unreasonable to as-
sume the secretion of a histolyzing ferment, in com-
parison to Endamoeha histolytica as the direct agent
of tissue destruction.

This tissue invasion, destruction, and production
of characteristic ulcers, may occur from the caecum
to the rectum, the larger and older lesions most com-
mon in the former part. When active and extensive
particularly, probably when the rectum is involved,
we have the clinical state of balantidial dysentery.

Here 'lasting from several days to several weeks
there may be numerous stools, of a bloody liquid

208

PROTOZOAN PARASITISM

character, or of blood-stained mucinous material, or
liquid feces without gross blood. The individual
may have more or less tenesmus, griping, abdominal
discomfort, pain, and tenderness. Depending on the

Fig. 34.

Balantidium coli within a vein, containing a thrombus, in the
subperitoneal coat of the colon in balantidial dysentery. Photo-
micrograph X 96.

activity and length of the course, there may be ir-
regular fever, weakness, loss of weight, various or-
ganic disfunctions, exhaustion, and even death.

The diagnosis depends upon the identification of
the parasite in the stool, it always being present in

OF THE ALLAIEXTARY TRACT 209

active swarms in the stool when diarrhoea is pro-
duced by it. The mucinous material shows the great-
est numbers.

Attacks of balantidial dysentery may sponta-
neously terminate in apparent recovery and after a
period, in which constipation is likely, an acute at-
tack may recur. Whether the organisms remain
within the colonic wall in these normal intermissions
or in case of apparent recovery or whether they are
then only lumen dwellers is unknown. We do know
that ulceration may be present without diarrhoea,
however, just as in the case of intestinal amoe-
biasis.

CHRONIC BALANTIDIOSIS

Much more common than the state of balantidial
dysentery is that in which there is an infection with
Balantidium coli without dysentery or even any ap-
parent disturbance due to it. It is unknown whether
in the ''carrier" state without symptoms of disease
the organism is purely a lumen dweller. In the com-
parable state in the pig, which is the rule, that is
apparently the case, although ulceration of the colon
of the pig may be produced, according to Brumpt
(1909). Haughwout (1918) reports Balantidium
coli in sections of pig's intestine in the tissues and
blood vessels, and gives the microscopic picture of
the infection as similar to that seen in human bal-
antidiosis. We may, it seems, infer that the organ-

210 PROTOZOAN PARASITISM

ism may dwell in the colon of man as a harmless
parasite.

Walker says that the latency prevalent in bal-
antidiosis of man is due chiefly to the fact that the
patient, although parasitized, is not ''infected," but
in part to the chronicity of the ulcerative process in
infected cases. He further states that a person in-
fected with Balantidium coli is liable sooner or later
to develop balantidial dysentery.

The state of infection in which there is a chronic
or mild and continued process of invasion and ulcera-
tion is naturally less known than the comparable
case of chronic intestinal amoebiasis, although when
symptoms of progressive disease are present they
may be more pronounced. Not uncommonly there
is a chronic and intractable diarrhoea, and emaciation
and anaemia may be conspicuous in the long stand-
ing case. Individuals showing symptoms of the in-
fection commonly run an intractable course of chronic
illness in which periods of dysentery alternate with
those of comparative well being or constipation.

TREATMENT

Preventive : Since it has been shown that the in-
fection of man may come from the pig, and that swine
are commonly carriers of Balantidium coli, it neces-
sarily follows that those who handle these animals
or are in close contact with them must exercise care
to avoid contamination of any object which is placed

OF THE ALIMENTARY TRACT 211

in the mouth by feces of this animal, if this danger
of contracting the infection is to be avoided. A sim-
ilar case may possibly be that of the monkey, since
this animal has been shown to harbor the infection
naturally.

Prevention of the spread of infection among hu-
man beings is, fortunately, not a matter for important
attention in this country or in most modern civilized
countries. Where the infection is prevalent, how-
ever, this is one more incentive for the application
of recognized methods of prevention of the swallow-
ing of human excrement.

Curative: Specific eliminative treatment is in
somewhat of a state of uncertainty. The older rem-
edies used are quinine, 1 to 1000, iodine, 1 to 10,000,
silver nitrate, 1 to 3000, tannin, etc., used by rectal
injection. Mason (1919) injected rectally oil of
chenopodium, 60 minims in one-half once of olive
oil, with apparent success in one case. Emetine and
other preparations of ipecac are largely discredited,
although some have thought they had a good effect.
Dobell (1921) thinks that the best chances of suc-
cess lie in the use by rectum of concentrated solutions
of quinine, such as used by Lanzenberg (1918), qui-
nine hydrochloride 0.75 gm. in 300 cc. of water, since
'Vectal injections of quinine often appear to relieve
the symptoms of balantidial dysentery, and to re-
duce the number of parasites, even when they do not
effect a radical cure."

Haughwout, Domingo and deLeon (1920) reported

212 PROTOZOAN PARASITISM

an apparently successful elimination of Balantidium
coll from a case of balantidial dysentery in extremis
by the use of benzyl benzoate. The drug was started
in doses of 10 drops of 20% alcoholic solution, given in
water three times a day. The same afternoon the
patient seemed to have experienced some relief and
he was distinctly better the next day. The follow-
ing day the dose was increased to 15 drops. Two days
later the bowel movement was more feculent and
natural. He continued to improve and four days
after the first increase the dose was raised to 20 drops.
Balantidia appeared in the stool the last time
sixteen days after beginning the treatment, at which
time the patient was apparently recovered. The
drug was continued altogether twenty-two days, when
the occurrence of vomiting and pain caused it to be
stopped. The patient died eleven days later of an
unrelated disease. No balantidia were found in the
content of the bowel, or in feces the day before death,
and extensive section of the scarred colon failed
to show any parasites in the tissue.

Aguilar (1925) reports that in his experience in
Guatemala, stovarsal apparently had a specific ac-
tion in the destruction of the organism in the intes-
tine. He recommends the reduction of carbohydrate
in the diet and the replacement of it largely by green
vegetables and fresh fruits. Stovarsal is given in a
0.25 gram tablet, two or three times daily, after meals,
for a period of seven days. After five days treatment

OF THE ALOIENTARY TRACT 213

in forty cases the stools of all were negative for bal-
antidia. Some of these cases examined two months
subsequently still showed none of the parasites.

Greene and Scully (1913) recommend the follow-
ing treatment, to be continued until the patient is
free of the parasite. Two and one-half quarts of
whole milk per day, given in small portions at regu-
lar intervals, supplemented after several days by one
or two soft boiled eggs. Bismuth subnitrate in 15
grain doses for the first few days, to relieve cramps
and diarrhoea. When the bowels become sluggish
stewed fruits are given.

It is to be hoped that some one or more of these
measures may stand the test of time.

BALANTIDIUM MINUTUM

Balantidium minutuvi was discovered by Schaud-
inn in 1899. He found it in two patients in Berlin,
both suffering from diarrhoea. Whether it is a patho-
genic species is unknown.

The body of the organism is more nearly of a pear-
shape than is Balantidmvi coli, and it is smaller,
measuring 20 to 30 microns by 14 to 20. The an-
terior end is more pointed and the mouthpiece is
longer and relatively more prominent. The peri-
stomal groove extends from the anterior extremity
deeply into the body, to about the middle, and is lined
by long, delicate cilia. The surface cilia are longer

214 PROTOZOAN PARASITISM

and more delicate than on Balantidium coli. There
is only one contractile vacuole, it being situated on
one side of the rounded posterior end of the body.

The macronucleus is rounded instead of kid-
ney shaped, measures 6 to 7 microns in diameter, has a
definite rim and its chromatin is more loosely ar-
ranged in granules through the nuclear network.
The micronucleus is about 1 micron in diameter,
spherical, and lies in front of the macronucleus. The
cyst is usually ovoid. Multiplication is by trans-
verse fission.

Our knowledge of this rare small ciliate is meagre
and it is of only scientific interest, if in reality it is a
parasitic species.

NYCTOTHERUS BABA

As with Balantidium minutum, Nyctotherus baba
is more of academic than practical interest, it having
been described in only one case, and that by Schaud-
inn also, in 1899. This patient suffered from diar-
rhoea and it was one of the two that harbored Balan-
tidium minutum.

This organism is beanshaped, measuring 26 to 28
by 16 to 18 microns, being even smaller than Balantid-
ium minutum. The mouthpiece extends from the
anterior end backwards into the body where it enters
the endoplasm through a short, oblique, narrow gul-
let. The peristome is lined by long delicate cilia,
the body covered by short fine processes. As in

OF THE ALIMENTARY TRACT 215

Balantidium viinutum there is only one contractile
vacuole, at the posterior end. The meganucleus is
spherical, 6 to 7 microns in diameter, is about the mid-
dle of the body, and the chromatin is arranged in
several large lobes. The micronucleus is about 1
micron in diameter. Oval cysts were seen by Schaud-
inn, possessing the characteristic nucleus.

CHAPTER XIII

The Coccidia

Classification. General Considerations. Life His-
tory. Habitat and Effects. Isospora belli. Isospora
hominis. Ewieria gubleri.

class: sporozoa.
order: coccidiida.
genus: isospora.

species: 7. belli.
genus: eimeria.

species: E. gubleri.

THE COCCIDIA (COCCIDIIDA)

The coccidia are very close akin in the protozoal
world to the parasites of malaria and have a some-
what similar life history, although it is carried out
wdthin one host instead of requiring two for its
completion, as in the case of the malarial parasite.
They are, consequently, obligatory parasites, spend-
ing a certain part of their life cycle wuthin certain
cells of their host's body, and are, therefore, always
and essentially pathogenic organisms.

While the class is widespread in the animal king-

216

OF THE ALIMENTARY TRACT 217

dom and of considerable commonness in some host
species, coccidia of man are not common. In fact,
while not rarely found in certain places, in this coun-
try and in most they are rare parasites.

The complete life history of none of the species
of man has been observed and it is necessary, in order
for an understanding of its probable nature, to give
the cycle of a typical species, such as has been com-
pletely studied in some other host.

While the life cycle of the coccidia is complex, it
is at the same time simple and easily understood.
The most confusion which comes to beginners is on
account of the names, difficult to a neophyte, which
are given to the different stages of the organ-
ism. These names, of course, have definite mean-
ings to those familiar with them but to the uninitiated
they are bizarre and difficult.

While the author is not unfamiliar with coccidia in
certain other animals and has studied the species
Isospora belli, through the courtesy of others, the
rarity of coccidiosis of man in this country has made
it impossible to give any material personal observa-
tions, and the discussion here is largely compiled
from the writings of others, particularly Dobell and
O'Connor (1921) and Wenyon (1926).

Description by word of the life cycle of coccidia
usually makes a confusing thing out of what is really
a simple process. It is best, therefore, to follow the
custom of outlining the sequence of stages by dia-
gram.

218 PROTOZOAN PARASITISM

It is essential to an understanding of it to realize
that the usual course of life is asexual but that periodi-
cally certain of the young organisms become differ-
entiated into males and females and these conjugate
to give a sexual cycle, presumably rejuvenating the
race.

In reference to the accompanying diagram, which
represents both cycles as they occur in a typical
species which inhabits the epithelium of the intestinal
mucosa, a graphic description of the scheme will be
attempted in as simple terms as possible.

Starting with (1), the young coccidium, a minute
ovoid organism within an epithelial cell, we see the
parasite grow to a size where it practically occupies
the whole housing cell, the cytoplasm of this cell being
fed upon and the nucleus crowded and flattened to
the bottom. This large asexual individual is called
a Schizont (2). As it grows larger its nucleus di-
vides and by repeated division becomes of a number
characteristic of the species (3). The cytoplasm
then splits (4) into as many new individuals as there
are nuclei, this process of division being known by
the term Schizogony. These young offspring are
elongated cycle-shaped or wormlike bodies, called
Merozoites. They are actively motile and their
housing cell is burst (5) leaving the remnants of
it and the parent Schizont. These Merozoites wig-
gle actively about and penetrate other host epithe-
lial cells (6), in which they become rounded and
from which point the asexual process of maturition

OF THE ALIMENTARY TRACT

219

Fig. 35. — Life Cycle of Coccidia.

Diagramnjatic representation of the asexual and the sexual cycles
within intestinal epithelium and of the development of the cyst,
stages 15-18, outside the body.

220 PROTOZOAN PARASITISM

and division is repeated. This is the ordinary process
taking place entirely within the parasite's habitat in
the single host.

Periodically in the life of the parasite, supposedly
as a rejuvenation process inherent in the organism,
but due to unknown influences, the Merozoites, af-
ter penetrating epithelial cells, instead of maturing
into asexual Schizonts, develop into male organ-
isms, called Microgametocytes (7 and 8), and females
(11), called Macrogametocytes. In the males the
organism grows, at the expense of the host cell, the
nucleus multiplies (9) and the body of the male
splits off a number of flagellated individuals (10)
corresponding to the number of multiplied nuclei.
These bodies, called Microgametes, burst the confines
of the host cell, leaving the remnant of it and the
parent Microgametocyte and swim actively about
until they come in contact with the female cell, cor-
responding to spermatozoa and their means of mak-
ing contract with the ovum.

The young female (]\Iacrogametocyte) after en-
tering an epithelial cell does not multiply in a com-
parable fashion but enlarges and matures, at the
expense of the cell host, into a single cell, called the
Macrogamete (12, 13), thus corresponding to the
ovum of the multicellular animal. The mature fe-
male element, the Macrogamete, is found by the male
element, the Microgamete, within the remnant of
the used up host cell ( 14) . When the free swimming
spermatozoon-like Microgamete, which is produced

OF THE ALIAIENTARY TRACT 221

in multiples of the female, thus continuing the anal-
ogy with germ cells of multicellular animals, meets
the passive, large, ovum-like Macrogamete, it pene-
trates at one pole, the nuclei of the two unite, and
the thus fertilized cell becomes the so-called Zygote
(15), which is then an inert body in the lumen of
the intestine.

Since this is the phase which is destined to con-
tinue the species in a new host and must withstand
external exposure in the process of transfer, it must
be resistant. It therefore becomes encysted, secret-
ing a cyst wall, and is now called an Oocyst. It is
this cyst in some stage of development which is ob-
served in the evacuated intestinal contents and upon
which the diagnosis of the infection depends.

As the Oocyst develops, passing down the intestine
and even after passage in the stool, the protoplasm
contracts and the nucleus divides and multiplies to
a number characteristic of the species ( 16) . Division
of cytoplasm now occurs around the nuclei, to form
an equal number of rounded bodies, called the Sporo-
blasts (17), leaving a remnant of the old protoplasm
as unused residue. Each Sporoblast now secretes
its own cyst wall, becoming encysted within the
Oocyst, the subcyst called the Sporocyst and each
enclosed body now a Spore (18). The organism in
each Spore divides into an equal and characteristic
number of worm-like bodies, being called Sporo-
zoites. This process of formation of spores in the
Oocyst is called Sporogony. The ripe Oocyst (18) is

222 PROTOZOAN PARASITISM

swallowed by a host-to-be, the Oocyst and Sporocyst
dissolved or burst (19) in the intestine, the Sporo-
zoite (6), liberated and active, enters an epithelial
cell and the process of asexual multiplication is begun
in the new host.

The transmissible form of the organism, the Spore,
is thus seen to be doubly protected, by the Oocyst
and the Sporocyst, the whole body resisting exposure
and remaining viable under conditions more severe
than may be borne by the comparatively non-resist-
ant cysts of other intestinal protozoa.

HABITAT AND EFFECTS

Although it is not definitely known it is presumed
that the coccidia of man inhabit the small intestine,
although an infection of the liver has been reported.

The organisms live during their asexual life in
the epithelium of the mucosa, consequently they are
essentially pathogenic. The cells w^hich are inhab-
ited are destroyed as the organisms mature and be-
come free. Naturally so long as this is all that occurs
and unless there is sufficient denuding to expose the
subepithelial tissues to bacterial invasion, it is not
anticipated that any considerable reaction, func-
tional disturbance, or symptoms, w^ould occur from
it. The loss and replacement of individual cells on
the surface of the intestine is probably of constant
occurrence under natural conditions. As a matter of
fact there is no definite clinical state associated with

OF THE ALOIENTARY TRACT 223

coccicliosis in man, and the host is usually, appar-
ently, in good health. In the intestine of infected
animals there is little evidence of reaction to the
presence of the parasite. On the other hand severe
and fatal diarrhoea or dysentery sometimes occurs
in other animals. In the liver of the rabbit, which
is commonly infected by its own species, there occurs
a papuliferous bile duct lining proliferation, of tu-
mor-like proportions at times. Wenyon (1926)
notes a case, reported by Connal, who, having acci-
dentally swallowed oocysts of 7. belli, developed
diarrhoea and abdominal discomfort in six days.
This persisted for four weeks and oocysts appeared
in the stool three weeks after the onset of symptoms,
being present for twelve days. The stools became
normal and recovery was complete.

In man intestinal coccidiosis is apparently a rare
and a self-limited infection. Most of the cases re-
ported have been in persons who had been in eastern
Mediterranean countries. However, Kofoid, Korn-
hauser and Plate (1919), and Kofoid and Swezy

(1920) reported finding eleven cases of the infection
in United States troops, seven of whom had seen for-
eign service and four of whom had not. Haughwout

(1921) reports a case from Manila which he thinks
originated in the United States.

Other cases have been reported from West Africa,
Java, Portuguese East Africa, Durban, Malay, China,
Calcutta, Argentine, Brazil, and Saigon.

Altogether there have been some one hundred and

224 PROTOZOAN PARASITISM

fifty cases put on record since Woodcock and Wenyon
initiated the modern interest in the infection, in 1915.
The most recent light on the nature of the species
occurring in man may be had from Wenyon (1926).
According to this authority intestinal coccidiosis of
man, in so far as it is known at the present, is due to
the species named by him Isospora belli.

ISOSPORA BELLI

Woodcock (1915), according to Wenyon (1926),
first discovered the immature oocyst of this coccidium
in feces of English soldiers invalided from Gallipoli.
Wenyon (1923) observed the complete development
of the oocyst, proving it of the genus Isospora, and
named it Isospora belli. According to him the coc-
cidium found in some one hundred and fifty cases of
intestinal infection since his and Woodcock's dis-
coveries belong to this species. They have usually
been identified as Isospora hoviinis.

The organism has been seen only in the oocyst
stage. It measures 25 to 33 microns in length and
about half that in width. It is elongated, one end
being constricted to the appearance of a neck.

The wall is of a double contoured outer layer and
a thin inner membrane. Within this cyst is a
rounded body of globules of refractive material,
within a clear space, the size of this body and that of
the surrounding space varying with the age of the
cyst, the older the smaller the body of the enclosed

OF THE ALi:\IENTARY TRACT

225

organism. Sometimes the first division, into sporo-
blasts, has occurred in fresh feces and there are two
smaller enclosed bodies instead of one. Further de-
velopment, the formation of sporocysts by the two
sporoblasts, the division of each sporoblast into four
sporozoites, leaving the rounded granular residual
body in each sporocyst, has been induced and de-

FiG. 36. — Isospora belli.
Drawings of oocysts from human stool, x 1200.

scribed by Wenyon and has been observed by others
to occur as the stool ages. The sporozoites are elon-
gated comma shaped bodies, the cytoplasm granular,
with a refractive globule in the larger end, the nucleus
anteriorly but indistinct.

In feces these oocysts are to be studied in wet un-
stained slide preparations. Since they are large they
are readily picked up with the ordinary low power
working lens. As they are transparent they may be

226 PROTOZOAN PARASITISM

overlooked unless the lighting is properly adjusted.
It is not improbable that they have occurred in feces
which have been examined microscopically but have
been overlooked. The impenetrability of the cyst
makes staining unsatisfactory. In fresh feces it is
only the first one or two stages of the oocyst that oc-
cur. Stools aged at ordinary temperature develop
in from one to three or four days, according to the
climate. The number of cysts is small, as a rule, and
they persist for only a few days, although Wenyon and
O'Connor (1917) observed them during twenty-five
days in one case.

Attempts to infect other animals experimentally
have apparently been failures and literally nothing
of proven nature, except the oocysts, is known of
the organism, its habitat or effects.

It is reasonably presumed that its habitat is the
small intestine, where it passes the phase of schizog-
ony in the epithelial cells, and that it is transferred
from host to new host by the ingestion of oocysts in
fecal contaminated food and drink. Direct transfer,
as is most effective in some other intestinal protozoa,
seems unlikely, since the most favorable state would
be the maturing of the oocyst, with the formation of
merozoites, before being swallowed by the host-to-be.

ISOSPORA HOMINIS

The infection of the interior of the villi of the
mucosa of the small intestine of a man recorded by
Virchow (1860) is, according to Wenyon, the only

OF THE ALIAIENTARY TRACT 227

reported instance of the occurrence of this species.
This conclusion is based upon the preciseness of Vir-
chow's record which would necessitate the organism
being much smaller than that seen since 1915 and
named by Wenyon Isospora belli.

Wenyon is inclined to think that Isospora hoiniins
will be rediscovered upon careful examination of the
mucosa of the small intestine.

It seems that Isospora hominis is like the small
form of Isospora bigemina of cats and dogs and that
it probably spends its life in the subepithelial tissues,
where the oocysts reach maturity.

The oocyst, in that event, should be about one-half,
or less, the size of Isospora belli. It should produce
two sporoblasts and sporocysts, each with four sporo-
zoites and residual body, in the matured stage. If
otherwise comparable to the small form of Isospora
bigemina in cats and dogs, its immature oocysts are
not released into the lumen of the intestine ordinarily,
and so examination of feces would usually fail to re-
veal the presence of the infection. Since it should
mature in the interstitial tissue of the villi, the oocyst
would be liberated only on disintegration of a diseased
villus, and in mature form with two sporocysts con-
taining four sporozoites and residual body each.

This is virtually a challenge to pathologists doing
postmortem examinations to discover this infection
by more careful microscopic section of the small in-
testine 'or by scrapings. That is, unless Virchow saw
an accidental infection of man by /. bigemina from

rAat>>/CV?

228 PROTOZOAN PARASITISM

the cat or dog, or unless he was in error in saying that
it was like this small coccidium, with which he was,
by the way, familiar.

EIMERIA GUBLERI

Since Thomson and Robertson (1926) have shown
that the three supposed human intestinal species of
the genus of coccidia known as Elmer ia, E. wenyoni,
E. oxyspora, and E. snijdersi (Dobell, 1919 and 1921),
are merely species from fish, ingested and passing
through the intestine in oocyst stage, it seems that
man's intestine is free of infection by this genus, al-
though it is a common one in certain other animals.

The only instances of Eimeria infection of man re-
maining are five liver infections, according to Dobell
(1921).

Gubler made the first report of such an infection
in man in 1858 and, although it is not definitely
proven that these cases were not really infections
with Eimeria stiedae, a common coccidium of the
liver of the rabbit, the name of Gubler has been
given to this supposed species of man.

The oocyst of this coccidium of man's liver is the
only stage described and it only in immature form.
It is of oval shape and about twenty microns in
length.

If it is in reality Eimeria steidae of the rabbit or
if it may be compared with that species, it should
occur in the epithelial cells of the bile ducts in the

OF THE ALIMENTARY TRACT 229

liver. There adenomatous tumors with papilliferous
growth of the tubule linings occur in the rabbit in-
fection. In the epithelium of these tumor-like bile
duct growths may be seen the various stages of the
endogenous cycle of development of the organisms.
These tumorous foci of coccidial habitation produce
gross white nodules in the liver substance. There
is a chronic cellular reaction and increasing fibrosis
associated with the papilliferous adenoma-like for-
mation. The oocysts escape from the bile ducts into
the intestine and are passed in the feces, from which
dissemination of the infection takes place. They are
liberated from the epithelium and escape from the
body in immature form. The oocyst of E. steidae
is from 20 to 40 microns in length and 16 to 25
microns wide. It is ovoid in shape, is of yellowish
color, and one pole is flattened. The ripe oocyst of
the genus Eimeria is spherical and it has four spaces
with tw^o sporozoites each.

Further information as to the identity of the coc-
cidium of man's liver is necessary before it can be
finally placed. Certainly such a disease as occurs
in the liver of the rabbit is not likely to be overlooked
at autopsy. It must be rare to the degree of a patho-
logic curiosity.

CHAPTER XIV

BLASTOCYSTIS

Although the organisms known as Blastocystis are
considered to be vegetable in nature and not pro-
tozoa, the confusion which has occurred in the past
and is likely to occur in inexperienced hands at the
present between these cells and protozoa makes it ap-
propriate to include here a brief consideration of
these parasites.

Alexeieff (1911) first called attention to the real
nature of certain cells which had been previously
described as cysts of Trichomonas hominis. He clas-
sified them as blastomycetes and gave the name
Blastocystis enterocola.

Brumpt (1912), who gave the name Blastocystis
hominis to the organism occurring in man, and Wen-
yon (1915), agreed with Alexeieff as to the nature of
the organism. The writer (1917) reported it as a
common intestinal parasite in this country, occurring
in all of twenty-five cases of pellagra at autopsy and
in the stools of 10% to 55% of several groups of in-
dividuals, mainly pellagrins. Barret (1921) first re-
ported its cultivation, in human blood serum diluted
ten times with 0.5% sodium chloride solution. Later

230

OF THE ALIMENTARY TRACT 231

(Lynch, 1922A and 1022B), the writer reported upon
culture experimentation with the organism and
named two new species, B. gemmagina and B. sporo-
gina, the former differing from B. hominis Brumpt
in exhibiting peripheral budding in culture, and the
latter in showing by the same method a process
taken to be endosporulation. Since that time much
incidental note has been taken of Blastocystis, par-
ticularly since it commonly grows profusely in a
number of the culture mediums used for growing
protozoa, often to the detriment of the purpose of
the cultures.

Blastocystis is a very common body to be seen in
the examination of feces. In the ordinary stool it is
usually not numerous, is about 5 to 15 microns in
diameter, usually rounded, but may be ovoid or more
elongated. It has a delicate capsule, allowing al-
teration in shape. There is a sharp differentiation
into peripheral and central zones, the former usually
of uniform width in the rounded organisms and
deeper at the poles of the ovoid or elongated than it
is around the middle. This peripheral zone is trans-
parent and colorless at times, at others greenish and
refractive. In it occurs the nucleus or nuclei, ap-
pearing as highly refractive bodies.

The central body is rounded or ovoid, depending
on the shape of the organism, and may be greenish
and refractive, when the peripheral zone is trans-
parent, or transparent, when the periphery is refrac-
tive. Not infrequently the division of the cell into

232

PROTOZOAN PARASITISM

two, four or more, may be seen in the feces, and oc-
casionally the peripheral budding.

In the stools of diarrhoea or dysentery, particularly
in liquid stools with inflammatory exudate, and not
uncommonly in the purged stool, the organism may

Fig. 37. — Blastocystis hominis.

Drawings of specimens from culture exhibiting the single cell
and multiplication to produce two and four. Stained by iron-
haematoxylon. x 900.

occur in enormous numbers and grow to large size,
a diameter of 25 to 40 microns being not uncommon.
In such specimens evidence of division is more com-
mon. In culture it grows profusely in several me-
diums, the serum saline medium being the simplest,
attains large sizes and shows numerous dividing

OF THE ALIMENTARY TRACT 233

forms. Young large forms in stool or culture are
delicate of structure.

Division of the body in the stool is ordinarily by
binary fission, the nucleus dividing apparently by
mitosis and the two daughter nuclei becoming lo-
cated at opposite poles. There is then a constriction
of the body, both peripheral zone and central body,
equally, to form symmetrical cells, or there may be
multiple fission, with 2, 4, 6, 8, or more, similar
daughter cells, all within a mucoid envelope which
is apparently a product of the organism. Peripheral
budding and endosporulation of species named B.
gemmagina and B. sporogina, in addition to binary
fission, may be studied in cultures.

Blastocystis is widespread in nature as a parasite
of the intestine of many animals. It is not known
as a free living body and is probably transmitted
from person to person and from animal to animal
through the contamination of ingested materials by
fecal matter. It is an inhabitant of the colon in
man. It is favored by inflammatory states of the
intestine and from time to time it has been indicted,
although not very seriously, as playing a causal
role in intestinal disease. The writer (1923) re-
corded its presence in rectal ulcers, where it increased
in size and numbers over those in the feces of the
host, and exhibited active division.

The organism is readily found in examination of
fresh wet preparations and, while it may be confused
with protozoan cysts by the inexperienced, its char-

234 PROTOZOAN PARASITISM

acteristic structure, once recognized, makes it easily
differentiated and identified.

In thin smear preparations it is well stained by
ordinary blood film methods, the peripheral zone,
nuclei, and central body being differentiated. In
iron-haematoxylon preparations the central body is
dark, the peripheral zone lighter and the nuclei
deeply stained.

In various of the mediums used for culture of in-
testinal protozoa it often grows when it has not been
seen in the feces.

Although Blastonjstis is an intestinal inhabitant
of most or all people and has been seen very com-
monly in stool examination and culture we really
know very little about its life. Its main importance
at the present time lies in the need for its recognition
by medical and other laboratorians.

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INDEX OF AUTHORS

Adams, A. R. D, 20, 41, 50, 249,

250
Aguilar. R, 212, 235
Alexeieff, A, 230, 235
Allen, E. A, 20, 101, 102, 103,

235, 243

Baetjer, W. A, 52, 235

Barret, H. P., 54, 56, 202, 230,

235
Barret, M. T, 105, 106, 112, 235,

247
Barrow, 132, 144, 170, 177, 236
Bass, C. C, 106, 111, 235, 236
Bateman, J. E., 71, 249
Baiimgartner, E. A., 23, 145, 170,

174, 175, 179, 248
Becker, E. R., 137, 241
Bensen, W, 149, 236
Blanchard, 4, 179, 236
Boeck, W. C, 22, 51, 55, 113, 144,

169, 173, 179, 192, 193, 236, 242
Bohne, A., 149, 236
Bovd, M. F., 142, 236
Brug, S. I, 49, 53, 236
Brumpt, E., 165, 209, 230, 236

Callender, G. R, 59, 79, 82, 83,

237, 240
Campbell, A. H, 179, 237
Castellani, 8
Castex, M. R, 177, 237
Chatterjee, G. C, 156, 237
Chatton, E, 52, 237
Chiang, F, 49, 53, 237
Chiavaro, A., 106, 237
Colwell, C, 166, 168, 238
Cort, E. C., 90, 237
Councilman, W. T., 69, 76, 80,

237

Craig, C. F., 14, 15, 48, 51, 56, 57,
62, 64, 71, 74, 92, 144, 198, 200,
237, 238

Cunningham, 94

Cutler, D. W., 54, 238

Davis, C. H., 166, 168, 238
Decks, W. E., 88, 91, 199, 238, 242
Derrieu, 156, 238
Dobell, C, 1, 22, 46, 54, 87, 94, 97,

113, 122, 153,179,201,202,211,

217, 228, 238, 242
Dock, G., 166, 238
Domingo, E., 211, 240
Drbohlav, J. J., 55, 113, 173, 236,

238

Escomel, E., 155, 166, 167, 238
Evans, J. S, 107, 239

Fantham, 14, 239

Faust, E. C, 123, 239

da Fonseca, O. O. R., 194, 239

Glaessner, K., 207, 239
Goodey, T., 140, 239
Goodrich, H. P., 114, 239
Grassi, B., 105, 179, 239
Greene, J. L., 213, 239
Greenway, C. J., 177, 237
Gros, C, 105, 239
Gubler, 228
Gunn, 102, 103

Hadlev, P. B., 150, 239
Haughwout, F. G., 59. 79. 82, 83,

156, 209, 211, 223. 239. 240
Hegner, R. W.. 16. 137, 139, 140,

144, 145, 150, 155. 159, 165, 166,

169, 179, 240, 241

251

252

INDEX

Hill, C. McD., 137, 145, 170, 180,

187, 188, 241

Hill, R. B, 137, 145, 170, 180, 187,

188, 241

Hinshaw, H. C, 111, 142, 158,

161, 241
Hlava, 52, 241
Hogiie, M. J., 142, 150, 158, 161,

165, 194, 241, 242
Hollander, E., 182, 191, 242
Howitt, B. F., 112, 113, 242

James, W. M., 40, 62, 66, 74, 75,

77, 88, 91, 242
Jepps. M. W, 46, 122, 144, 169,

238 242
Johns', F. M, 106, 111, 235, 236,

242
Jones, P. H, 91, 242

Kartulis, S., 52, 242

Kessel, J. F, 25, 50, 53, 102, 149,

242, 243
Koch, D. A, 113, 243
Kofoid, C. A., 56, 71, 86, 91, 96,

101, 102, 103, 110, 111, 112. 114,

123, 141, 148, 156, 159, 170, 173.

179, 191, 194, 223, 243, 244
Kornhaiiser, 179, 194, 223, 244
Kovacs, F., 52, 244
Kruse, W., 52, 244

Lafleur, H. A., 69, 76, 80, 237

Lambl, W., 179, 245

Lanzenberp;, 211

de Leon, 156, 211, 240

Lewis, 94

Losch, F., 44

Lynch, K. M., 23, 49, 53, 63, 82,
96, 98, 103, 107, 110. Ill, 119,
140, 141. 142, 145, 149, 150, 151,
157, 158, 165, 170. 172, 175, 180,
194,230,231,233,245,246

Macfie, 71
Mackie, J. W., 246
Malmsten, 198, 200

Manlove, C. H., 204, 246
Marchand, F., 166, 246
Mason, C. W., 211, 246
Matthews, J. R., 179, 246
Maxcy, K. F., 179, 247
McDaniel, J. C, 199
McLoon, M., 190, 250
Middleton, W. S., 105, 106, 107,

239, 247
Mmnich. D. E., 243
Miura, R., 166, 247
Moseley, 114, 239

Noguchi, H., 113, 140, 142, 158,

247
Niitt, M. M., 179, 247

O'Connor, F. W., 22, 87, 94, 97,
117, 191, 192, 194, 217, 226, 238,
249

Ohira, T., 113, 140, 142, 158, 247

Pasqiiale, A., 52, 244
Payne, G. C, 144, 169, 179, 240
Pentimalli, 149
Plate, 179, 194, 223, 244
Prince, L. H., 102, 103, 249
Pringaiilt, 142

von Prowazek, 105, 149, 172, 236,
247

Quincke, H., 52, 247

Ratcliffe, H., 140, 155, 159, 240,

241, 247
Raynaud, 156, 238
Reuling, 166
Rivas, D., 163, 247
Robertson, A., 119, 121, 123, 173,

193, 228, 248
Rogers, J. H., 243
Roos, E., 52, 247

Scully, J. F., 213, 239

Scllards, A. W., 52, 78, 235, 249

Smith, 179. 246

Smith, A. J., 105, 106, 112

Smith, M. T., 54, 56

INDEX

253

Smith, N. M., 54, 235
Smithies, F., 129, 145, 170, 247
St. John, J. H., 57, 101, 238, 248
Steinberg, S., 105, 140, 157, 247
Stephens, 14, 239
Stiles, C. W, 22, 144, 169, 179,

236
Strong, R. P., 204, 248
Swezy, O., 96, 101, 102, 110, 123,

156, 170, 173, 223, 244

Tanabe, M., 248

Theobald, 14, 239

Thomas, W. S., 23, 145. 170, 174,

175, 179
Thompson, M. D., 53, 66, 173, 248
Thomson. J. G., 16, 119, 121, 123,

193, 228, 248
Turner, R. H, 91, 242

Ucke, A., 149, 248

Virchow, 226

Wagener, E. H., 16, 56, 64, 86, 91,
244, 248

Walker, E. L., 49, 78, 198, 204,
210, 248. 249

Warsley, A. N., 71, 249

Warthin, A. S., 70, 249

Wenyon, C. M., 54, 87, 97, 102,
103, 117, 119, 120, 141, 149, 157,
165, 172, 177, 186, 191, 192, 194,
217, 223. 224, 226, 227, 230, 249

Werner, 172

Wight, T. H., 102, 103, 249

Woodcock, 224

Yarborough, N., 56, 202, 235
Yorke, W., 20, 41, 50, 249, 250

Zahorsky, J., 188, 190, 250

INDEX OF SUBJECTS

Abscess, amoebic, of liver, 68, 70

amoebic, of lung, 69
Achlorhydria and flagellates, 130
Acidity, gastric, and flagellates,

130
Amoeba, Amoebae. 7, 30
classification of, 29, 30
cultures of, 40
cysts of, 39, 41
cytoplasm of, 31
encystment, 31
general considerations, 30
incidence of, 26
iron-haematoxylon method

for, 34
method of examination of, 32,

37,42
morphology of, 31
nucleus of, 31
of mouth, 105, and see Enda-

moeba gingivalis
reproduction of, 32
staining of, 34
undulating, 8
Amoeba dentalis, 105
Amoeba undularis, 8
Amoebic abscess, of liver, 68, 70

of lung, 69
Amoebic colitis, 59, 61, 63, 65,
66, 67, 72, 73, 79, 80
dysentery, 77, 79
'diet in, 89
drugs in, 86
pathology of, 80
stools in, 82, 84
treatment of, 85
ulcer, of colon, 53
Amoebiasis, intestinal, 74
pathology of, 75

Amoebiasis intestinal,
treatment of, 85
diet in, 89
drugs in, 86
oral, 105, 114
pathology of, 68
Amoebidae, 29, 30, and see

Amoebae
Anacidity, and flagellates, 130
Animals, transmission of proto-
zoa by, 24, 28
Antibodies, 16

Appendicitis, and flagellates, 132
Arthritis deformans, and flagel-
lates, 132
Autoinfection, protozoa and, 27

Baclllary dysentery, 82
BalantidiafcoHtis, 205

dysentery, 204
Balantidiosis, 203, 204

chronic, 209
Balantidium coli, 24, 29, 56, 198,
200, 205, 206, 208

effects, 203

habitat, 203

morphology, 200

prevalence, 198

transmission, 28, 199

treatment, 210
Balantidium minutum, 29, 213
Blastocystis, 39, 96, 56, 149, 150.
230

enterocola, 230

gemmagina, 231, 233

hominis, 56, 230, 232

sporogina, 231, 233
Blepharoi^lasts, 7
Bloody flux, 80

254

INDEX

255

Boeck and Drbohlav's medium,
55

Capsule, 2

Carriers of parasites, 14

of protozoa, 26
Caudamoeba, 30

sinensis, 123
Cercomonas, 126
Chilomastix. 29, 126. 134, 135
mesnili, 29, 129, 130, 136, 149,
169, 171
effects, 176
habitat, 175
morphology, 170
prevalence, 169
transmission, 27, 28, 174
treatment, 177
Cholecystitis and flagellates, 131
Chromatin, 11
Chromatophores, 10
Chromidial bodies, 12
Cilia, 8

Ciliata, 29, 196, and see Ciliates
Ciliates, 196

characteristics, 196
classification, 29, 196
Coccidia, 216

classification, 29, 216
effects, 223

general considerations, 216
habitat, 222
hfe cycle, 219
life history, 217
Coccididia, 216, and see Coccidia
Coccidiosis, 223

Colitis, amoebic, 59, 61, 63, 65,
66, 67, 72, 73, 79, 80
balantidial, 205
Colon, amoebic ulcer of, 53
Commensals, 13

Contact, transmission of proto-
zoa by, 27
Councilmania, 30, 96, 99

lafleuri, 20, 96, 97, 101, 102
Craig's complement fixation, 75
medium, 56

Cysts, 2

characteristics of, 12
iodine, 120, 121
of amoeba, 39, 41
protozoan, 12

Diarrhoea, and flagellates, 132

flagellate, 126
Dientamoeba, 29, 30

fragilis, 29, 122
Diet, and parasitism, 16, 17
Duodenal ulcers, and flagellates,

131
Dysentery, amoebic, 77, 79

pathology of, 80

stools of,' 82, 84

treatment of, 85
diet, 89
drugs, 86

bacillary, 82

balantidial, 204

flagellate, 126

Ectoplasm, 6

Eimeria gubleri, 28, 29, 228

oxyspora, 228

snijdersi. 228

stiedae, 228

wenyoni, 228
Embadomonas, 29, 126

intestinalis, 29, 135, 194, 195
transmission of, 28
Encystment, 17, 18

and reproduction, 19

failure of in protozoa, 23
Endamoeba, 29, 30
Endamoeba barreti, 54, 56
Endamoeba coli, 29, 39, 85, 94, 95

effects, 100

experimental information, 101

habitat, 100

importance of, 100

morphology, 94

nucleus, 95, 98

precystic form, 97

prevalence, 100

transmission of, 28

256

INDEX

Endamoeba gingivalis, 29, 31,
105, 109

effects, 112

experimental information, 113

habitat, 110

history, 105

morphology, 108

prevention of, 114

relation to pyorrhoea alveo-
laris, 105,110, 112

transmission of, 27, 28

treatment, 115
Endamoeba histolytica, 29, 34,
38, 39, 40, 42, 44

and immunity, 16

appearance, 44

carriers of, 49

cultivation, 54

distribution, 49

effects, 64

excystation of, 20

experimental information, 52

habitat, 58

prevalence, 47

transmission, 25, 28, 51
Endamoeba nana, 117
Endamoeba ranarum, 56
Endamoebiasis, oral, 108
Endolimax, 30
Endolimax nana, 29, 117, 118

transmission, 28
Endoplasm, 6, 10
Entamoeba buccalis, 105

nana, 121
Enteromonas, 126, 193
Enteromonas caviae, 194
Enteromonas hominis, 29, 135,
194

transmission, 28
Excreta, transmission of proto-
zoa by, 22, 24
Excretion, by protozoa, 10
Excystation, 20

Experimental amoebic ulcer of
colon, 53

Feces, transmission of protozoa
by, 22, 24

Flagella, 7

Flagellata, 125, and see Flagel-
lates
Flagellate diarrhoea, 126

dysentery, 126

infection, 126
Flagellates, 7, 125

and appendicitis, 132

and arthritis deformans, 132

and cholecystitis. 131

and diarrhoea, 132

and disturbances of gastric
secretion, 130

classification, 29, 125

examination for, 133

general considerations, 125

prevalence of, 127

relations, 130
Flagellosis, 126, 128
Flies, as carriers of protozoa, 24
Food, transmission of protozoa
by, 23

Gastric disturbances and flagel-
lates, 130. 131
Giardia, 126, 134, 135
Giardia enterica, 158, and see

Giardia intestinalis
Giardia intestinalis, 29. 129, 130,
136, 178. 183, 185
effects, 188
examination for, 181
habitat, 187
incidence, 179
morphology. 182
transmission of. 28
treatment, 189
Giardia lamblia. 178, and see

Giardia intestinalis
Giardiasis, 187
Gram's iodine solution, 38

Haemalum, 36

Heterotrichida. 29

Hog, transmission of protozoa

by. 25
Hosts, immunity of, 15
of parasites, 14

INDEX

257

Hosts, resistance of, 15

specificity of parasite for, 14
Hyperchlorhydria and flagel-
lates, 130

Immunity, 15, 16
Infection, dissemination of, 22
flagellate, 126
prevention of, 22
Infusoria, 196
Intestinal amoebiasis, 74
pathology, 75
treatment, 85
diet, 89
drugs, 86
Intestinal protozoa, incidence

of, 22
Intracystic reproduction, 13
lodamoeba, 30
biitschlii, 2y, 120

transmission of, 28
williamsi, 121
Iodine cysts, 120
Iron-haematoxylon method for

amoebae, 34
Isospora belli, 29, 224, 225
transmission of, 28
bigemina, 227
hominis, 29, 226

Karyamoebina falcata, 123

Karyosome, 11

Kissing, transmission of proto-
zoa by, 22

Kofoid and Wagener's medium,
56

Lamblia intestinalis, 178, and
see Giardia intestinahs

Linin, 11

Liquids, transmission of proto-
zoa by, 23

Liver, amoebic abscess of, 68, 70

Locke's solution, 55

Locomotion of protozoa, 6, 7, 8

Lumen dweller, 60, 77

Lung, amoebic abscess of, 69

Macrogamete, 220
Macrogametocytes, 220
Macronucleus, 197
Mastigophora, 29
Mayer's haemalum, 36
Meganucleus, 197
Membrane, undulating, 8
Merozoites, 218
Metazoa, 5
Microgametes, 220
Microgametocytes, 220
Micronucleus, 197
Monadida, 29

Nucleus, 11 ^

Nyctotherus baba, 29, 214 A~^

Oocyst, 221 ^

Oral endamoebiasis, 108
Organelles, 6

Parabasal body, 185
Paramecium, 198
Parasites, 14

carriers of, 14

host of, 14
Parasitism, diet and, 16, 17
Pentatrichomonas, 156

ardin delteili, 156
Pores, 9

Precystic form of protozoa, 17
Protozoa, anatomy of, 4

carriers of, 24, 26

classification of, 29

encysted, 23

excretion by, 10

failure of to encyst, 23

food of, 9

general consideration of, 1

history of, 1

incidence of, 26

life of, 1

life history of, 13

locomotion of, 6, 7, 8

physiology of, 4

precystic form of. 17

reproduction of, 20

transmission of, 22. 23, 24. 25,
27,28

258

INDEX

Protozoan cysts, 12

Pseudopodia, 6

Pyorrhoea alveolaris, and Tri-
chomonas elongata, 158
relation of Endamoeba gingi-
vahs to, 105, 110, 112

Rat, transmission of protozoa

by, 25
References, 235

Reproduction, and encystment,
19

intracystic, 13

of protozoa, 20
Resistance of host, 15
Rhizopoda, 29
Rigg's disease, 107

SaHva, transmission of protozoa

by, 22
Schaiidinn's sokition, 34
Schizogony, 218
Schizont, 218
Spore, 221
Sporoblast, 221
Sporocyst, 221
Sporogony, 221
Sporozoa, 29
Sporozoites, 221
Stomata, 9
Symbiosis, 13

Tanabe's medium, 173
Tetra trichomonas, 140
buccalis, 140, 157
hominis, 140
Transmission of protozoa, 22, 23,

24, 25, 27, 28
Tricercomonas, 126, 129
intestinalis, 29. 191
transmission of, 28
Trichomonas, 23, 126, 134, 135,
139, 193
cultivation of, 142
terminology, 140

Trichomonas buccalis, 29, 139,

140, 157, and see Trichom-
onas elongata

transmission of, 27, 28
Trichomonas caudata, 141, 157
Trichomonas caviae, 16, 18, 149
Trichomonas elongata, 141, 157,
159

and pyorrhoea, 158

effects, 162

habitat, 162

morphology, 159

relations, 158

treatment, 162
Trichomonas fiagellata, 141, 157
Trichomonas hominis, 29, 129,
130, 139, 141, 144, 147, 157

effects, 149

habitat, 149

prevalence, 144

relations, 145

transmission, 27

treatment, 153
diet, 155
drugs, 153
Trichomonas vaginalis, 139, 140,

141, 142, 157, 163, 165
effects, 167

habitat, 167

prevalence, 164

transmission, 27, 28, 166

treatment, 167
Trichomoniasis, 152
Tritrichomonas, 156
Trophozoite, 95

Ulcer, duodenal, and flagellates,
131

gastric, and flagellates, 131
Undulating amoeba, 8

membrane, 8

Vacuoles, 10

Yorke-Adams' method for
amoeba, 41

Zvgote, 221