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CORNELL UNIVERSITY
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Special Report Series, No. 59.

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MEDICAL RESEARCH
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ay

A Report on the Occurrence of Intestinal
Protozoa in the Inhabitants of Britain

LONDON
S. MAJESTY'S STATIONERY OFFICE

PUBLISHED BY |
3 1921.

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MEDICAL RESEARCH
COUNCIL

A Report on the Occurrence of Intestinal
Protozoa in the Inhabitants of Britain
with special reference to

Entamoeba histolytica

LONDON
PUBLISHED BY HIS MAJESTY’S STATIONERY OFFICE
1921

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No, 1/6389
Medical Research Council.

The Viscount GoscHeEn, C.B.E. (Chairman).
Wruitiam Granam, M.P.
The Hon. Epwarp F. L. Woon, MP. (Treasurer).
C. J. Bonn, C.M.G., F.R.C.S.
Professor Witt1am Butwocu, M.D., LL.D., F.R.S.
T. R. Exnrort, C B.E., D.S8.0., M.D., F.B.S.
Henry Heap, M.D., F.RS.
Professor F, G. Hopxins, D.Sc, F.R.C.P., F.B.S.
Major-General Str Winn1am Letsuman, K C.M.G., C.B., F.B.S.
Professor Norn Paton, M.D., F.R.S.
Str Watrer M. Frercner, K.B.E.,M.D.,Se.D., F.R.S. (Secretary).

15 BuckINGHAM StTREEt,
Stranp, W.C. 2.

A REPORT ON THE OCCURRENCE OF
INTESTINAL PROTOZOA

IN THE

INHABITANTS OF BRITAIN

WITH SPECIAL REFERENCE TO

ENTAMOEBA HISTOLYTICA

BY

CurrrorD Dose, F.R.S.
(Protistologist to the Medical Research Council)

with contributions by

A. H. Campse.t, B.Sc.
T. Goopry, D.Sc.
R. C. McLean, MA.
Mvurtet M. Nutt,

and
A. G. THacxer, A.R.C.S.

CONTENTS

CHAPTER
I. Inrropuctory .

II. Tue Oper Recorps or THE OccurRENCE or InTESTINAL PROTOZOA IN
THE PopuLATION OF BRITAIN .

III. Recent Reports oN THE OccURRENCE o¥ InTESTINAL PROTOZOA IN 1HE
PopruLaTion oF BRITAIN .
A. The Liverpool Reports .
B. The Later Reports
(1) Birmingham
(2) Brighton
(8) Bristol ‘ 7
(4) Leeds and Sheffield
(5) Reading . : . ‘ ‘ - ‘ : e
(4131), Ps. 2409. Wet. 22691. 306/375. 1500. 1,21. O.U.P. A2

PAGE

CHAPTER PAGE
IV. Summary or Att Reports, anp Discussion or Crrrain Posts or
ParricuLar InTEREstT _ . F . : : aj ‘ . 389
A. The Incidence of Protozoal Infections in Pergons who have never
left Britain . - ‘ ‘ , . : x . 39
General Results. ‘ : : - . 389
(1) Entamoeba histolytica. . : x ‘ : . 42
(2) Entamoeba coli . 4 - : ‘ : . 48
. (3) Endolimax nana . F ; ; : ; . 49
(4) Iodamoeba biitschlit 3 : . . - 50
(5) Dientamoeda fragilis _ F A F : : . 650
(6) Giardia intestinalis : Z : : c j 51
(7) Chilomastia mesnili é ¢ ‘ i : A . 62
(8) Trichomonas hominis. . ‘ . : ‘ 53
(9) Other Protozoa . di * . i : z : . 54
B. The Spread of Infections in Britain. - ‘ , ° . 54
V. ReEcENT OBSERVATIONS ON THE OccURRENCE or E, histolytica 1Nn FRANCE,
HOoLLanD, AND GERMANY . i ‘ ‘ ‘ 7 ; 7 . 57
VI. Concitupinc Remarks . ‘ 2 - : ° ‘ . 63
REFERENCES. : F 4 : 2 ‘ ‘ é X . 69

CHAPTER I. INTRODUCTORY.

Prior to the outbreak of war in 1914 little was known con-
cerning the occurrence of intestinal protozoa in the population
of the British Isles: for although many British investigators
had devoted their attention to the study of the intestinal protozoa
of man in tropical countries, it seems to have occurred to nobody,
until very recently, to carry out similar investigations at home.

The reasons for this—which seems, at first sight, somewhat
curious—are not difficult to discover. Diseases due to intestinal
protozoa were not generally recognized as occurring in Britain.
They were—and still are—-regarded by most practitioners as
peculiar to the tropics; and it therefore appeared unnecessary to
look for the ‘causes’ of such diseases in a country wherein they
seemed generally absent. Moreover, Protozoology, as a serious
study, has usually been regarded as entering into the purview of
those physicians only who devote themselves to the study of
Tropical Medicine: and consequently there were few medical
men who were able—or, if able, who saw any necessity—to study
the intestinal protozoa of the resident population of Britain.
And, on the other hand, those zoologists who might have been
disposed to take up this work were usually debarred from doing
so by the difficulty, or the impossibility, of obtaining adequate
material,

All this was soon changed by the War. Large bodies of troops

“were raised in Britain and sent to all the theatres of military
operations, where they contracted divers intestinal diseases with
which later they returned home. On their return they were
subjected to careful examination, in order to diagnose their

5

maladies with precision. Numerous workers were specially
trained for this investigation, on the protozoological side, and in
due course trustworthy figures were obtained for determining
the incidence of infections with various intestinal protozoa among
the particular class of case studied. The results have already
been published in an earlier Report,! and elsewhere, and need
not be further considered here. It will suffice to note that
these returned soldiers were infected, to a considerable degree,
not only with the common and well-known non-pathogenic
intestinal protozoa, but also, and in a somewhat surprisingly high
proportion, with Entamoeba histolytica—the ‘dysentery amoeba’.

It was known before the War—chiefly through E. L. Walker’s
observations and experiments in the Philippines—that carriers
of E. histolytica are not uncommon. Such persons, though
harbouring active and facultatively pathogenic amoebae in the
walls of their intestines, may present no clinical symptoms of
infection: and they are, in consequence, indistinguishable from
uninfected individuals unless their stools are subjected to careful
microscopic examination. In 1914 it was still uncertain what
percentage of persons who become infected with LE. histolytica
might be expected to develop into carriers of this type, and what
proportion might be expected to suffer from dysentery or liver
abscess, or to display other clinical signs of amoebiasis. Con-
sequently, it was impossible to state, with any certainty, the
precise significance of the high rate of infection with E. histolytica
discovered in the convalescent dysenteric patients returning to
Britain from the various theatres of war.

It soon became clear, therefore, that further facts, obtained
from a different class of persons, were necessary for the proper
comprehension of those already accumulated. The mere fact that
some 25 per cent. of dysenteric convalescents, returned from
Gallipoli or elsewhere, were infected with E. histolytica told us
very little: for we were not told how many non-dysenteric cases
from the same area were infected, nor what percentage—if any—
of the whole body of troops was parasitized before setting out
from England originally. In other. words, we were presented
with the end result of an experiment in which the earlier steps
were unknown, and alongside of which no control experiments
had been performed.

The first steps towards acquiring the necessary knowledge
were taken early in 1916, when an attempt was made to examine
the stools of soldiers invalided to England for disabilities other
than dysentery. In those days it was difficult to examine non-
dysenteric patients, as there were large numbers of dysenteric
convalescents—whose diagnosis and treatment were urgent, on
military grounds—awaiting examination in the hospitals and
dépéts in this country. I succeeded, however, in investigating
some cases of the former class at No. 2 New Zealand General
Hospital, Walton-on-Thames. The number was not great, but
the results were somewhat surprising. I examined altogether

1 See Dubell (1917). i: 2 See Dobell (1916).
(4181) As

6

110 non-dysenteric patients, and as a control a series of 90
dysenteric cases also—only 200 cases in all. The ‘dysenteric’
cases were all patients who had been invalided to England from
Gallipoli and Egypt suffering, or having recently suffered, from
‘dysentery ’—diagnosed, in most cases, on clinical grounds only.
The ‘non-dysenteric’ class consisted of patients invalided from
the same areas for affections other than dysentery: but they
included 40 cases of non-dysenteric intestinal ailments—the
remaining 70 being wounded men and others with various non-
intestinal complaints. The results obtained from all these

different classes of patients were as follows:
Infected with.

Cases. No. examined. E., histolytica,
per cent,
All cases . F r P w¥ 200 : ‘ : 11.0
Dysenteric ‘ a : 90 ‘ i 3 10.0
Non-dysenteric s ; : : = 110 ‘ : E 11-8
Allintestinal ailments . é 7 P 130 , 5 ‘ 8-2
All non-intestinal ailments - F 70 é . ‘ 15.7

So far as these figures went, therefore, they did not warrant,
the conclusion that the cases being returned to England labelled
‘dysentery’ were more heavily infected with ZF. histolytica than
those who were coming here by reason of their wounds or other
non-dysenteric disabilities.

In the summer of 1916 I undertook, in collaboration with
Dr. A. C. Stevenson, the examination of another series of non-.
dysenteric cases—the convalescent typhoid and paratyphoid cases.
at Hornchurch Dépét. We examined the stools of 472 such,
patients, and found that 9-74 per cent. of them were infected with
LE, histolytica.

These observations were sufficient to indicate the importance
of making further investigations along similar lines: and accord-
ingly I urged all the protozoologists whom I had trained for the
work of diagnosis at military hospitals to examine as many non-.
dysenteric cases as possible. Some of them did so, but owing to.
the requirements of the Army it was difficult to obtain adequate
material for investigation... Mr. W. O. Redman King examined
the stools of non-dysenteric patients in Graylingwell Military
Hospital, Chichester! He was able to study 59 men—mostly
wounded—and found 8-5 per cent. infected with E. histolytica.
Mr. R. E. Savage, at the 2nd Southern General Hospital, Bristol,”
was also able to examine a number of paratyphoidal cases and
a few patients suffering from wounds and other non-intestinal
ailments, and obtained similar results. Miss M. W. Jepps, at.
Hampstead Military Hospital,? examined 65 soldiers invalided.
for ‘irritable heart’; and among these she found—after an,
exhaustive inquiry—that no less than 24 were infected with
E. histolytica. Some of these at least had never suffered from
dysentery or other intestinal ailment. A few other workers.
made similar observations, but on a smaller scale. The most.

1 See Dobell (1917), p. 59. 2 See Hall, Adam, and Savage (1916).
3 See Jepps and Meakins.(1917).

7

extensive series, however, was that studied at Liverpool by
Mr. A. Malins Smith and Mr. J. R. Matthews, who have published
two detailed reports on their findings (Smith and Matthews, 1917,
1917 a), Taken together, their two series of cases show that, of
450 non-dysenteric patients, 35, or 7-7 per cent., were infected
with E. histolytica. All the cases were patients in hospitals—
200 soldiers invalided for various diseases other than dysentery,
and 250 non-dysenteric patients in a civil hospital.

It should be noted here that EH. histolytica was not, of course,
the only intestinal protozoon which was sought and found among
non-dysenteric cases. Other amoebae, and all the flagellates
which were so frequently encountered in the stools of the
dysenteric patients, were also found to be not uncommon: some-
times, indeed, there seemed to be but little difference—if any—
between the incidence of intestinal protozoal infections in the
two classes of cases. It must be remembered, also, that these
cases—whether they were returned as ‘dysenteric’ or ‘non-
dysenteric ’—were nearly all derived from similar areas, The vast
majority of them came from Egypt and Gallipoli; and although
the ‘non-dysenteric’ class consisted of men who were not
invalided to England for dysentery, a very large proportion of
them, when carefully questioned, were found to have suffered
recently from dysentery or diarrhoea or some other intestinal
disorder during their service abroad. Nevertheless, there were
some ‘non-dysenteric’ patients—though comparatively few—who
were certainly infected with FE. histolytica and from whom no
history of intestinal disorder could be elicited. These men
appeared to be true contact carriers of the parasite—as defined
by Walker (1913); but how long they had carried their infec-
tions, and whether they had acquired them originally abroad or at
home, were questions upon which the findings threw no light.

There were, in 1916, two individual cases, well known to all of
us working in London, which were of special interest. The first
of these was studied and described by Dr. C. M. Wenyon (1916).
The patient was ‘a labourer in London, who had never been out
of England’, but who ‘had worked on a transport then lying in
dock’. Hecontracted dysentery and was admitted to the London
Hospital, where his symptoms disappeared. He remained ill,
however, and was found to have a liver abscess, which was opened
and drained. In the scrapings from its wall, active E. histolytica
amoebae were found, and the cysts of the same parasite were
found in his stools. The patient died, and at autopsy a second
abscess was found in his liver, and a few small amoebic ulcers in
his large intestine. This was undoubtedly, therefore, a case of

1 In their first report, Smith and Matthews (1917) remark (p. 365) that their
results—namely, the finding of a considerable percentage of E. histolytica infections
among soldiers invalided for diseases other than dysentery—were ‘ confirmed’ by
mine (Walton Hospital, 1916). This is a somewhat misleading statement, as my
results were obtained and published first, and theirs actually supplied a confirmation
of mine. The work of Smith and Matthews was, indeed, carried out at my
suggestion—as they fully acknowledged (p. 389) : and I made the suggestion because
of the results that I had already obtained whilst working along similar lines. :

A4

8

E. histolytica infection acquired in England ; but at the time it
appeared probable—as Wenyon inferred—that the patient had
contracted his infection ‘from material from some carrier case
who had been at the dock or on the transport’.

The second case was one which has been recorded by Dr. G.C.
Low and myself (Low and Dobell (1916), Case 3). The subject
was a young man who attended my class, in 1916, for instruction
in the routine examination of stools, in order to take up the work
of diagnosis at a military hospital. Like the other members of
the class, he subjected his own stools to careful microscopic
examination, and was surprised to find that he was passing cysts
of E. histolytica—an observation which I was able to confirm.
This worker had never at any time suffered from dysentery,
persistent diarrhoea, or other intestinal disorder, and displayed
no symptoms of intestinal disturbance at the time of the dis-
covery. He had, however, been abroad—to Switzerland, Southern
France, and Northern Italy—though never in the tropics or in
any places where amoebic disorders were known to be prevalent,
and had resided in England for the preceding five years. It
seemed probable, at the time, that he had accidentally acquired
his infection in the laboratory, jn the course of examining stools
containing cysts of E. histolytica. Two circumstances, however,
led me to doubt the correctness of this supposition. In the first
place, this worker was particularly careful and cleanly in his
work—in fact, so fastidious, owing to his natural repugnance to
handling stools, that he seemed the least likely of any member of
the whole class to acquire an infection accidentally. The second
point was this: he was infected with a race of HE. histolytica
forming cysts of unusually large size,) and—so far as I could
ascertain at the time—no sample of faeces containing similar
cysts had been examined by him whilst he was working with me.
I am now inclined to believe that in this case the infection was
really not acquired in the laboratory, but that the subject was a
contact carrier who had unknowingly been infected for some
years at least, and had contracted his infection very probably in
the British Isles.

There is one other case which became known at about the
same time and which ought, perhaps, to be placed in the same
class as the two just mentioned. This is the case recorded by
Worster-Drought and Rosewarne (1916). The patient was a
soldier who had never left England, but had lived all his life in
or near Manchester. He enlisted in 1915, and was admitted to
the Royal Herbert Hospital, Woolwich, in the following year,
with a typical attack of acute amoebic dysentery. . histolytica
was found in his stools ; and he recovered rapidly, and apparently
completely, as a result of emetine treatment. No carriers of
E. histolytica could be found among this patient's companions ;
but whilst it is certain that he was a case of amoebic dysentery

1 That the cysts were those of E. histolytica there can be no question: and con-
firmation—if it were needed—is supplied by the fact that the infection was entirely
eradicated. by treatment with emetine bismuth iodide.

9

acquired in England, the manner in which he became infected
is, as in the other cases just mentioned, still uncertain.

At this time it was generally recognized that carriers of
E. histolytica are by no means rare in the tropics, and probably
also in sub-tropical countries. That many soldiers returning from
the Near Eastern theatres of war were infected with the parasite
had been shown conclusively: and as EH. histolytica was not
known to occur in the normal civil population of Great Britain,
it seemed natural to suppose that the returning carriers con-
stituted the source from which were derived the few known
eases of infection undoubtedly acquired in this country. A very
important point, however, which made one hesitate to accept this
conclusion unreservedly was this: E. histolytica was known to be
disseminated in the same way as the other protozoa of the human
bowel—the harmless amoebae and flagellates. These we knew to
occur in persons who had never left the British Isles. Why,
then, should not &. histolytica, if once introduced into this
country, spread through the population in precisely the same
manner? That there had been abundant opportunity for its
introduction in the past could hardly be doubted: and consider-
ing this question in all its bearings, I soon came to the conclusion
that it would be somewhat remarkable—to say the least—if
E. histolytica were absent, at the present time, in the native
British population. Against this supposition, however, was the
tact that typical amoebic diseases—dysentery and liver abscess—
appeared to be extremely rare in this country. Yet this objection
might not be very cogent: for we were beginning to realize that
amoebic diseases are not very common even in countries where
E. histolytica is notoriously endemic, and that carriers of the
parasite, displaying no clinical symptoms of infection, are far
commoner than was originally supposed. We knew at that time,
with a fair degree of certainty, that the dysenteric.convalescents
reaching this country from abroad were heavily infected with
&. histolytica: but we also knew—or were beginning to know—
that the dysentery from which these patients had suffered in the
field was, in most cases, not amoebic but bacillary. From reliable
observations made on the spot it seemed certain that less than
10 per cent. of the dysentery in the armies abroad was due to
E. histolytica; whereas in the same troops, when they reached
England, twice or thrice this percentage were found to be carriers
of the parasite.

Another fact also came to light in the winter of 1916-17.
Soldiers returning to England from the French front, many of
them men who had never at any time been in any countries save
England and France, were also found to be infected to a consider-
able extent with £. histolytica. Mr. Redman King, at Barton
Dysentery Dépét, investigated a number of such cases; and in-
a series of 1,300 convalescent. dysenteric patients, whom I
examined at this time at the Manor War Hospital, Epsom, I found!

1 See Dobell, Gettings, Jepps, and Stephens (1918).

10

—after a most careful inquiry into their past histories—that
no less than 8-37 per cent. of the men (788 in number) who
had been in England and France only, were carriers of EF. histo-
lytica. Amoebic diseases were not known to be more prevalent,
in normal circumstances, in Northern France than in Great
Britain; and moreover, it was fairly certain that by far the
greater number of the dysentery cases occurring on the French
front were bacillary—not amoebic. Consequently, unless infection
with £. histolytica had spread through our armies from. the
associated colonial troops—and had spread with remarkable
rapidity, and without concomitant clinical manifestations—it
seemed certain that carriers of the parasite must be far com-
moner than had hitherto been supposed in the native population
of Great Britain, of France, or of both countries.

The only way to arrive at the truth of the matter was obvious.
The civilians—the normal resident population—would have to be
subjected to examination in the same way as the military
patients. In this way alone could the findings from the latter
class be properly interpreted. But this was not easily done. It
was difficult to obtain samples of faeces from a large number of
persons who had never been abroad; and yet such material was
obviously necessary for this investigation. Anybody who had
been out of Britain would have to be excluded; for it would be
impossible, if protozoa of any sort were found in his stools, to
ascertain whether the infection had been acquired at home or
during his sojourn in foreign parts: and this meant that a very
careful inquiry would have to be made into the history of every
case that was to be included in our ‘ British’ series. Then again,
it was obviously necessary to examine as large a number of the
‘ British’ population as possible, since a small sample might give
a wrong idea of the real conditions. And finally there was the
difficulty of obtaining workers for the undertaking. The investi-
gation, if it were to be of any value, would have to be made by
competent workers, whose findings could be trusted: and the
men and women whom I had trained for this purpose, and upon
whose diagnoses reliance could be placed, could ill be spared
from the hospitals where they were then employed in the
examination of military patients. Their work for the Army
naturally took precedence of all other work.

I made several attempts to carry out investigations of this sort
myself, but owing to preoccupation with other more urgent
duties the results which I obtained were insignificant. But I
endeavoured to. impress upon all the workers whom I trained
from time to time for the War Office the importance of conduct-
ing inquiries into this problem; and I urged them all to seize
every opportunity of obtaining the information needed. For
various reasons the majority of these workers were unable to
devote their attention to the matter; but one group of them,
acting upon my suggestions, ultimately succeeded in obtaining
data of the greatest interest. I refer, of course, to the workers at
the Liverpool School of Tropical Medicine, whose results have

ll

now been fully published and are already well known. The work
was begun by Mr. A. Malins Smith, Mr. J. R. Matthews, and Miss
Doris L. Mackinnon, who passed through a course of training
with me in London in the early part of 1916, under the scheme
arranged by the Medical Research Committee and the Royal
Society for the War Office. On going to Liverpool these workers
were joined by Mr. H. F. Carter, and received the assistance of
Professor Warrington Yorke. Later Mr. Malins Smith and Mr.
Matthews continued the work alone, and it is to their efforts that
most of our present knowledge is due.

I shall consider this important work, carried out in Liverpool,
in greater detail in later chapters, and will here merely note
briefly the general results. In a first report (Yorke, Carter,
Mackinnon, Matthews, and Malins Smith, 1917), results were
recorded of examinations of the stools of 844 persons who had
never left Great Britain. Of these, 138 were ‘patients, for the
most part surgical, in the Liverpool Royal Infirmary; they con-
sisted of both males and females of various ages’: the rest (206)
‘were healthy young men of about 18 years of age who had
recently entered the army and were in training at a camp in the
vicinity of Liverpool’. No less than 10 of these (2 in the first
group, 8 in the second) were found to be infected with E. histo-
lytica—a percentage, for the whole, of 2-9, or roughly 3. This
figure was obtained, moreover, as a result of making only a single
examination of the stools of each case, so that it certainly repre-
sents less than the number actually infected. None of these 10
infected individuals had ever suffered from dysentery. The cysts
in their stools were typical in every way; and further evidence
that they were really those of E histolytica was obtained by
animal experiment—a kitten fed upon cysts from one case
developing typical and fatal amoebic dysentery:

Further results were announced in the following year in a
Report to the Medical Research Committee (Carter, Matthews,
Mackinnon, and Smith, 1918), and at a meeting of the Society
of Tropical Medicine and Hygiene (Yorke, 1918); and again in
1919, at a-meeting of the British Medical Association (Yorke,
1919). Since then Mr. Malins Smith and Mr. Matthews have
published a complete account of all their findings (Matthews
and Smith, 1919,1919a). The five reports published by them
summarize the results obtained in the examination of British
residents—never abroad—belonging to the following classes:
(1) Civilians in an infirmary, (2) Army recruits, (3) Children,
(4) Asylum patients, (5) University and school cadets. Infections
with £. histolytica, ranging from 1-5 per cent. (infirmary patients)
to 9-7 per cent. (asylum patients), were found in all these series.
Other protozoa were, of course, also found and recorded, but will
be considered later in the analysis of the total findings from all
sources.

Investigations along somewhat different lines were made
during 1917 by Dr. P. P. Laidlaw at Guy’s Hospital. He searched
for E. histolytica in patients with symptoms suggestive of infection

12

with this parasite in the hope of finding indigenous cases of
amoebiasis; and he soon succeeded in finding three such cases
(Laidlaw, 1918). The first case was one of chronic amoebic dysen-
tery: the second a case of amoebic abscess of the liver, without
concomitant dysentery but with abundant cysts of E. histolytica
in the stools. Neither of the patients had ever been abroad.
Both were males, aged 88 and 48 respectively, admitted to
hospital in the usual way—Case 1 for ‘ulcerative colitis’, Case 2
with ‘lumbar and abdominal pain’. The diagnosis of the second
case was arrived at only after laparotomy and evacuation of the
abscess thereby discovered. Typical specimens of E. histolytica
were obtained from both cases,! and from both kittens were
inoculated and successfully infected. Emetine treatment also
had a beneficial effect on both patients. The third case reported
by Laidlaw was based upon material supplied by Dr. Perdrau,
who showed him sections of an intestinal ulcer and a liver
abscess found post mortem in a woman who had never left Britain.
In both these EF. histolytica was present.

Evidently these were all cases of indigenous amoebiasis, and
they would probably all have passed unrecognized if they had
not been specially looked for. They were found among the
ordinary admissions to a large London hospital in the same year;
and from his experience Dr. Laidlaw was led to suggest that,
even in Britain, ‘cases of this type are not so rare as might be
thought from the literature’, He concluded ‘that cases of
ulcerative colitis, colitis, and liver abscess should always be
examined with a view to excluding amoebic infection’.

In the summer of 1918, the War Office Committee on Dysentery,?
with the results of the Liverpool workers and others before them,
decided that further inquiry into the incidence of EH. histolytica
infection among the resident civilian population of Great Britain
-was desirable. The time was considered opportune to utilize the
services of some of the trained workers, then engaged in examining
dysenteric convalescents at military hospitals, for this purpose—
the pressure of work at these establishments having, at that
moment, somewhat abated: and I was asked by the Chairman of
the Committee to organize and supervise investigations, with the
aid of the personnel then available at various centres, along the
lines followed by the workers at Liverpool and with the object of
checking and amplifying their findings. Accordingly, in July
1918, I invited five of the protozoologists working at military
hospitals to investigate, as far as possible, the protozoal infections
occurring in the resident civilian populations in the areas in
which they were situated. These workers had all been through
a course of instruction with me in London before they were
employed at military hospitals; and as they had all, by this time,

1 Dr. Laidlaw kindly sent me specimens for examination, and I had no difficulty
in confirming his diagnosis.

2 Consisting of Major-General Sir William Leishman, K.C.M.G. (Chairman),
Sir Walter Fletcher, K.B.E., Professor (now Sir) F. W. Andrewes, Dr. G. S. Buchanan,
C.B., Dr. G. T. Western (Secretary), and the present writer.

13

had considerable experience in this line of work, it was believed
that reliance could be placed upon their findings. These five
protozoologists were :

A. H. Campbell, B.Sc., 2nd Southern General Hospital,
Bristol.

T. Goodey, D.Se., lst and 2nd/lst Southern General
Hospitals, Birmingham.

‘R. C. McLean, M.A., Reading War Hospital.

Miss M. M. Nutt (Bathurst Student, Newnham College,
Cambridge), Leeds and Sheffield Military Hospitals.

A. G. Thacker, A.R.C.S., Kitchener Hospital, Brighton.

Mr. Campbell and Mr. Thacker were working under grants
from the Medical Research Committee: the three others were
in the service of the War Office. They all expressed their
willingness to collaborate in the undertaking, and were then
supplied with cards for the recording of their findings. These
cards, which were issued by the Medical Research Committee,
were designed—by myself, in consultation with Sir Walter
Fletcher—so as to indicate the kind of information required, and
in order to enable the examiners to record their findings, and
such essential facts as they could elicit regarding the histories
of the cases studied, in a uniform manner and with economy of
spaceand time. The form of the card is shown on p. 14—its actual
measurements being 12-5 x 20 cm.—and it may be added that
it appears to have fulfilled its objects. Apart from this pro-
vision for collecting and correlating the results, all arrange-
ments for the work were left in the hands of the protozoologists.
themselves. They were all able, with the assistance of the
medical officers in charge, and in some instances with aid from
the Medical Research Committee and the Local Government.
Board, to obtain the necessary material from various local
institutions.

As all the workers were engaged simultaneously in the routine.
work of diagnosis for military hospitals, they could devote only a.
fraction of their time, as opportunities occurred, to the examination
of civilians. There were naturally many difficulties to be sur-
mounted—-differing from time to time and from place to place—
and the several workers did not all enjoy equal facilities for the
prosecution -of their inquiries. This explains, to a large extent,
the inequality of their results. Nevertheless, every worker was
able to investigate a certain number of cases; and in due course
each was able to submit a report of the results. The largest
series of cases—and the fullest report—came from Miss M. M..
Nutt (Leeds and Sheffield); but she had already begun her inquiry,
at my suggestion, before the matter was taken up by the War:
Office Committee. The reports are all printed here for the first
time (see Chapter III), and deal, in the aggregate, with the
findings from the examination of the stools of over one thousand

(4131) Ad

14

Examined Case No.
at

Name Sex

Occupation Age

Usual Place of Residence

Places of Residence abroad, with dates

Previous attacks of Dysentery Where ? When?

Persistent Diarrhcea ?

Liver Abscess ?

PROLUZOOLOGICAL EXAMINATIONS OF STOOLS.

Dates Findings.

Remari.s

15

British civilians who have never, at any time, been abroad.
Nobody who realizes the difficulties involved in such an under-
taking will be disposed to complain of the smallness of this
mumber. On the contrary, it’ will, I think, be generally conceded
‘that to have found and examined so large a number of persons of
this class constitutes, when all the circumstances are borne in
mind, a performance which does the greatest credit to all the
workers concerned.

The investigation was gradually discontinued in 1919, following
the Armistice and the disbanding ofthe Army, and the consequent
reorganization of Dysentery Hospitals and Dépéts and the return
of the temporary protozoologists to their ordinary civil employ-
ments. By the beginning of the present year (1920) the reports
from all the centres, together with the cards, duly filled up, were
iin my hands; and it was then possible to collect, analyse, and
classify the results obtained from all sources. This is the main
purpose of the present Report.

It should be added here that at the time when the War Office
‘Committee decided to promote these inquiries, a similar investiga-
tion had already been begun in the Navy. After the publication
-of the results obtained by the Liverpool workers, Surgeon Captain
P. W. Bassett-Smith, C.B., R.N., urged upon the Admiralty the
importance of investigating the new entries to the Royal Navy,
in order to ascertain the extent to which they were infected with
E. histolytica and other intestinal protozoa. Accordingly, arrange-
ments were made by Surgeon Lieutenant-Commander P. Fildes,
R.N.V.R., at the Royal Naval Hospital, Haslar, for carrying out
this investigation. Examinations were made by Mr. H.A. Baylis
—one of the protozoologists previously trained for this work, like
the others, by me in London—of 400 healthy men joining the Navy
and Marines. Reports on his findings have already been published
(Baylis, 1919, 1920), and will be noted in greater detail later. It
will suffice to notice here that ten cases of &. histolytica intection
were found among these men—all healthy individuals, drawn from
various parts of the British Isles.

It is not possible to include this series with the others for the
purposes of this Report. Particulars of past history were not
obtained for every case, as ‘it was thought sufficient to make
special inquiry as to the history of each case found to be a carrier
of Entamoeba histolytica’. Consequently, as some of the cases had
probably been abroad, they cannot be regarded as forming a series
exactly comparable with the others in this respect. A set of cards
was sent to Mr. Baylis, but at that time his investigations were
already in progress, so that he was only able to enter on them
particulars of the cases infected with E histolytica. As Mr. Baylis
kindly returned these cards to me when his inquiry was published,
I have been able to utilize them in considering his results and
comparing them with the rest.

In dealing with the material at my disposal for this Report
I have not confined myself to analysing the work that was insti-
tuted by the War Office Committee. This work, to be properly

A6

16

appreciated, must be taken in conjunction with that done
previously. The cases examined by the Liverpool workers were
more numerous, and really form the backbone of the whole inquiry.
The newer findings here presented are supplementary, and the
two series must be added together in order that their significance
may have a maximal value. Moreover, since no comprehensive
treatment of this subject has previously been possible, and since,
in consequence, no complete survey of it has been attempted,
it has seemed to me opportune to summarize all the information
at present available. I have therefore extended the scope of the
present Report so as to include the following subjects—to each
of which a separate chapter will be devoted:

1, The older records of the occurrence of intestinal protozoa in
the population of Britain.

2. The recent reports on the same subject—comprising a sum-
mary of the results obtained by the Liverpool workers, and the.
newer findings of the workers under the War Office Committee.
(now published here for the first time).

3. A summary of all the results so far obtained, with a dis-
cussion of certain points of particular interest.

4. A brief review of certain similar observations recently made
in France, Holland, and Germany.

And ina final chapter I will present very briefly what seem
to me to be the most important conclusions deducible from the
facts recorded in all the antecedent chapters.

Infections with intestinal protozoa are, in general, very per-
sistent ; and we know that they are by no means uncommon in
many foreign countries. Consequently, it has seemed to me
necessary, for present purposes, to investigate particularly the
intestinal protozoa of persons who have never been abroad.
When such persons are found to be infected, it can be said with
certainty that their infections were acquired in Britain. It may
be urged, however, that even in such cases the infection may not
be truly indigenous, but may have been acquired from some im-
ported foreign source—from a home-coming soldier, for example,
returning from a country where the infection is endemic. This.
objection is, I think, negligible ; for even if the explanation were
true, it would not invalidate the conclusion that infection can be
acquired in this country, and it would demonstrate, moreover,
that the conditions here are suitable for such infections to spread
—a very important point. For if they can spread now, they
could have done so before, and with a fluctuating population like
ours there is every reason to suppose that the infection—whatever
it may be, and whenever it may have been first imported in the
past—would thus long ago have established itself and become.
as truly ‘endemic’ as 1t was in its country of origin.

As regards the present classification of records into ‘ old’ and
‘new’, I would only remark that it is purely arbitrary, and done.
for convenience. What we have seen occurring during the War

17

must have been going on—probably more slowly—for centuries:
but it is only recently that attention has been devoted to the
subject, and that any considerable body of observations has been
amassed. The outbreak of war in 1914 forms a convenient
dividing line for my present purposes, and I have therefore
called all records prior to this date ‘old’, and all those since
‘new’.

In the next chapter I shall now analyse, as briefly as possible,
all the old records which I have been able to find in the literature.

CHAPTER II. THE OLDER RECORDS OF THE OCCUR-
RENCE OF INTESTINAL PROTOZOA IN THE POPU-
LATION OF BRITAIN. °

Tae occurrence of intestinal protozoa in the population of the
British Isles—that is, in residents who have never been abroad—
has been the subject of serious inquiry only since the outbreak of
the War. Consequently almost all that has been definitely
ascertained has been the product of the last half-dozen years.
Nevertheless, it was known prior to 1914 that amoebic dysentery
and liver abscess do occur sporadically in Britain, and several
apparently indigenous cases had been recorded. Of such cases
I have been able to find but five for which the evidence appears
at all convincing. I shall summarize them briefly at this point,
as they are of interest in two respects: first, from a historic
standpoint; secondly, because they show that EH. histolytica
occurred in the population of Britain before the War—that is,
before the recent demonstration of its presence.

Although it was doubtless well known to many people before
the War that E. coli, Giardia, and other non-pathogenic species
of intestinal protozoa occur in the resident population of the
British Isles, I have been unable to discover any printed records
of this in pre-war literature. Consequently this chapter will
deal entirely with records relating to the occurrence of E. histo-
lytica.

The older evidence for the existence of E. histolytica in persons
who have never left Britain is, of course, mainly pathological and
clinical. But the symptoms and lesions of such infections are
very characteristic; so that, notwithstanding the fact that the
certain recognition of E. histolytica is a comparatively recent
achievement, it is possible to draw conclusions from several of the
older records with some degree of certainty.

I shall now review, in their historic sequence, all the ‘old’
records which I have been able to find.

Dickinson’s two cases.—The earliest British case of E. histo-
lytica infection known to me is that recorded by W. Howship
Dickinson (1862). His patient was a woman aged 37, who came
under observation at St. George’s Hospital. ‘She had never been
out of England. She was ‘sallow’, and complained of ‘pain in
the right hypochondrium’, and a tumour could be felt extending

18

from the liver area to below the umbilicus. ‘The bowels were
confined.’ She ‘had been ill for one year’, with ‘pain about the
region of the liver’; but she did not ‘admit that she had ever
had any looseness of the bowels’. ‘The ordinary symptoms of
dysentery were, as far as could be ascertained, altogether absent.’
In hospital she was constipated, and died 8 days after admission.

At the post-mortem examination a large single abscess, con-
taining about 1 gallon of pus, was found in the right lobe of the
liver. ‘The upper part of the large intestine was in a state of
ragged ulceration, such as occurs in dysentery. It ceased abruptly
at the edge of the ileo-caecal valve. The absorbent glands in the
neighbourhood were red and swollen.’

Though no amoebae were described in the pus from the abscess:
or in the ulcers in the gut, the symptoms and lesions recorded
are so typical, in every way, that it is hardly possible to doubt:
that this was a case of E. histolytica infection.

Nearly 20 years later, Dickinson (1881) recorded a second
case. The patient was a man—a lath-splitter, aged 36—who
was also admitted to St. George’s Hospital. On admission he
was ‘ febrile’, with a ‘temperature ranging pretty regularly from
about 98° in the morning to 102° in the evening’. He was found
to be suffering from severe dysentery, which was followed by
a liver abscess. The disease ended fatally ‘38 days after the first
symptom’. Previous to this illness the patient had enjoyed
good health, and it is stated that he ‘had never left England’.

At the autopsy, ‘the large intestine presented from end to end
a patchwork of dysenteric ulcers, separated by narrow ridges of
thickened mucous membrane. The ulcers were very irregular in
size and shape ; they were for the most part deep, some exposing
the muscular coat of the bowel. ... The small intestine was
healthy. The liver contained a large single abscess which held
about four ounces; it lay in the back part of the right lobe near
its upper and posterior surface. The shape was irregular, its
walls ragged, and without lining membrane.’

After discussing the post-mortem findings, Dickinson says:
‘I think we have no choice but to look upon the ulceration and
the abscess as cause and effect, and upon the portal vein as the
connexion. He thus came very near to what is probably the
correct interpretation, for I have no doubt that this also was
a case of E. histolytica infection. Everything recorded is abso-
lutely typical of amoebic dysentery and liver abscess. It requires
only the finding of amoebae in the abscess and the ulcers to
make the description complete. Such a discovery, however,
could hardly have been expected at the time when Dickinson’s
observations were recorded.

Moore’s case—In the year in which the preceding case was
recorded, another probable case of E. histolytica infection was
briefly noted by Norman Moore (1881). His patient was a little
girl, aged 33 years, admitted to St. Bartholomew’s Hospital,
where she died about 5 weeks after admission. ‘The child had
never been out of London.’ She had two abscesses in her liver,

19

‘one in the right lobe as large as a small orange, and one in the
lett lobe of the size of a filbert.’ The abscesses had ‘ very definite
boundaries ’, and the neighbouring liver-tissue appeared healthy.
‘The whole of the large intestine was extensively ulcerated’;
and it is further recorded that the child ‘had been ill ten months
with diarrhoea, and for about two months there were slime, blood,
and general. symptoms of dysentery’.

Though little else of importance is recorded, it seems highly.
probable that this was another case of amoebic dysentery and
liver abscess—due to EF. histolytica—in a person who had never
left Britain.

The case of Saundby and Miller.—‘ A case of amoebic dysentery
with abscess of the liver in a patient who had never been out of
England’ was described some years ago by Saundby and Miller
(1909) in Birmingham. This was another fatal case. Their
patient was a man—a cycle-rim maker who had lived in the
Birmingham district all his life. From the clinical description and
the recorded post-mortem findings, the case appears undoubtedly
to have been one of amoebic abscess of the liver, with typical
amoebic ulceration of the large bowel. No history of dysentery is
recorded, but it is stated that ‘four days after admission’ the
patient ‘passed a stool containing a considerable quantity of
blood’—which apparently was not examined microscopically—
and thereafter he had ‘no more diarrhoea’. The liver abscess
was 5 in. in diameter, in ‘the posterior part’ of the liver,
and contained ‘brownish-red pus and masses of necrosed liver
substance’, Amoebae were found in the pus, from which no
bacteria were cultivated ‘in ordinary media’, and similar amoebae
were present in the intestinal ulcers. The authors identified
them as ‘the Entamoeba histolytica (Schaudinn)’, though un-
fortunately this organism cannot be recognized in their description
and figures. There can be little doubt, however, on other grounds,
that this was really a case of H. histolytica intection.

Saundby and Miller claimed that theirs was ‘the first ob-
servation of the kind which has been recorded in Great Britain’ ;
and it appears probable that it was, indeed, the first such case in
which amoebae were actually found. They appear to have thought
that the patient contracted his infection from some ‘imported’
case of amoebic dysentery: but they adduced no evidence in
support of the suggestion. They concluded that ‘the disease,
although no doubt imported into this country from time to time,
rarely spreads; that it may do so, however, when circumstances
favour it, seems to be established by the present case’. The
authors could hardly have written this last sentence if they had
known all that we now know concerning the occurrence of
E. histolytica in Britain.

Marshall's case.—This is another comparatively recent case,
described by Marshall in 1912. The patient was a ploughman,
aged 28, living near Dunbar. He had never been out of Scotland.
He was admitted to the Royal Infirmary, Edinburgh, ‘ suffering
from chronic diarrhoea’, which had begun about seven weeks

20

before. His stools were generally ‘watery’, but also contained
blood and mucus; and numerous amoebae—identified as Enta-
moeba histolytica—were present in them. Attempts were made
to infect cats with the amoebae, but at the time of writing the
result. of the experiments was not known. The patient was
treated with ipecacuanha, which appears to have benefited him:
for though he relapsed after a first course, he was, when the paper
was written, ‘almost convalescent’ after a second.

It is uncertain how this patient acquired his infection.
Marshall suspected that he might have got it from a soldier, who
had been in India, in the same neighbourhood. But this soldier
was not proved to be a carrier of L. histolytica. ‘Spores’ were
present in his stools, ‘but whether they were the spores of
Entamoeba histolytica could not be determined by mere micro-
scopic examination’.

It appears probable that Marshall's case was also one of
Fi. histolytica infection, though the published evidence is not
wholly satisfactory. The author appears to have held peculiar
views regarding the life-history of &. histolytica; and from his
description and figures it is, unfortunately, impossible to identify
the organisms with which he was dealing. Corroborative evi-
dence from animal experiments and emetine treatment is also—
as already implied—lacking.

There are other cases of possibly indigenous E. histolytica
infection on record, but as they all appear doubtful as ‘British’
cases, I shall not consider them here. It is possible, however,
that some of them were really indigenous. The case of Bassett-
Smith (1900) will serve as an instance of these doubtful cases,
and illustrates the difficulties of interpretation. His patient,
a petty officer in the Navy, had been abroad, but had never pre-
viously suffered from dysentery. More than two years aiter
returning home to Portsmouth he had an attack of dysentery,
followed by the formation of abscesses in the liver and lung.
The pus from the former was bacteriologically sterile, but con-
tained active forms of ‘the amoeba coli’. The disease ultimately
proved fatal. It seems clear that this was a case of E. histolytica
infection; but there is no evidence to show where or when the
patient originally became infected. He may have acquired his
infection whilst abroad, and have remained a contact carrier of
the parasite until his fatal illness developed. On the other hand,
in the absence of evidence to the contrary, it is possible that he
contracted his infection in England—either before he went
abroad or at any time after his return.

As it is impossible to determine the facts with certainty, I have
excluded several other doubtful cases, of a similar type, from the
present chapter.

21

CHAPTER III. RECENT REPORTS ON THE OCCUR-
RENCE OF INTESTINAL PROTOZOA IN THE POPU-
LATION OF BRITAIN.

In this chapter I propose to set out the recent records of the
occurrence of intestinal protozoa in the British population. The
greater part of the chapter will consist of the new reports—now
published for the first time—from the investigators working at
Birmingham, Brighton, Bristol, Leeds, Sheffield, and Reading.
Reference to these investigations has already been made in the
Introduction (p. 12). As there noted, they were undertaken,
under the direction of the War Office Committee on Dysentery, in
order to amplify the observations of the workers at Liverpool.
It thus seems proper to preface them with some account of the
Liverpool workers’ results, which have now been fully published.
I shall therefore begin by giving a brief summary of this pioneer
work, before passing on to the later records.

I may note here that there are, in addition to the reports
given in this chapter, three other recently published records of
the occurrence of FE. histolytica in persons who have never been
abroad. (1) Baylis (1919, 1920), as already noted, found 10 men
infected among 400 naval cases at Haslar; and of these 8 had never
left the British Isles. (2) Miss D. L. Mackinnon (1918) examined
34 ‘British’ cases among patients at University War Hospital,
Southampton, and found one &. histolytica infection in aman who
had never been abroad.' (3) Tayler has recorded an infection
with Z. histolytica in ‘one man who has never been out of England’,
examined at Addington Park War Hospital, Croydon. It is
stated that he ‘probably contracted the infection while employed
unloading transports at Southampton Docks’, but the evidence
for this conclusion is not given. (See Turner and Tayler (1919),
p. 249, footnote.) All these cases are of interest, in that they
supply further information concerning the occurrence of E, his-
tolytica in Britain; but as other essential particulars are not
available, I have not been able to include them with the other
results recorded in this chapter.

A. The Liverpool Reports.

Four years ago Smith and Matthews (1916) recorded—appa-
rently for the first time—the occurrence of Giardia intestinalis
(= Lamblia) in two men who had never been outof England. Later,
in collaboration with others (Yorke, Carter, Mackinnon, Matthews,
and Smith, 1917), they reported the presence of Entamoeba
histolytica, E. coli, and Chilomastix mesnili also, found during the
examination of a series of 344 persons who had never been

1 This man was ‘an R.A.M.C. sergeant who had attended to dysentery patients
on hospital trains’. The other infections found in this series were with £. coli (5),
E. nana (8), Giardia (6), and Chilomastix (1).

(4181) AZ

22

abroad. The same workers gave further accounts of their ob-
servations later (Carter, Matthews, Mackinnon, and Smith (1918) ;
Yorke (1918, 1919); Matthews and Smith (1919, 1919a); Smith
(1919)). The last two reports published by Matthews and Smith
in 1919 contain their final results in detail, and it is from these
that the following figures have been mainly compiled.

(1) Crvittans in Liverproot Roya Inrirmary.

At this institution 450 cases—chiefly surgical—were examined.
None of the patients had ever been abroad. The series included
men, women, and children, selected at random. Only ‘a com-
paratively small number’ had been admitted for intestinal
ailments. The stools were examined only once apiece for the
whole series, and the findings recorded were as follows:

« Total No, of cases examined . E ‘ . é 450
Infected with: per cent,
Entamoeba histolytica : * F i F 1-5
E. coli . ‘ ‘ 7
Endolimax nana é c “ , . 2-4
Todamoeba biitschlii . . i Z ‘ ‘ ‘i 1 case
oes Giardia intestinalis 6.0
Chilomastix mesnilé 1.5

(2) Army Recrurrs.

More than a thousand young army recruits who had never
been out of England were examined in this series. They were
stationed near Liverpool, and had been in camp for times ranging
from a few days up to five months. Only one examination per
case was mace, and the total findings were as follows:

Total No. of casesexamined . : 3 ‘ - 1,098

Infected with : per cent.
Entamoeba histolytica ‘ * % “ F 5:6
Eley a é a a . . 7 18.2
Endolimax nana . P 4 P 7 ‘ 5-5
LIodamoeba biitschlit . i "i * ‘ ‘ é 0.4
Giardia intestinalis 7.0
Chilomastix mesnili . 2 cases

(3) CHILDREN.

‘Material for the investigation was obtained at the Liverpool
Infirmary for Children, where all the patients are under 12
years of age. The cases examined were in hospital for various
diseases, the great majority being non-intestinal.’ None had
ever been abroad, and the total findings, based on a single
examination per case, were as follows:

Total No. of casesexamined 3 A ‘ . 548
Infected with : per cent.
Entamoeba histolytica é ‘ F a ; 1:8
E.coli. % ‘ ‘ . i 7 . F 11.1
Endolimax nana a . ‘ . 7 i 2.7

Iodamoeba biitschlit . ‘ 0 le
Giardia intestinalis . - ¢ ‘ é 3 14.1
Chilomastix mesnili . 1.8

23

(4) Asyzum Patients.

Matthews and Smith (1919a) examined the stools of 207
patients in the Lancashire County Asylum, Whittingham. The
patients were all males, their ages ranging from 17 to 87. As
in the other series, only one examination per case was made.
None of the patients had ever been abroad. The findings were
as follows:

Total No. of cases examined . é . 7 ‘ 207
Infected with : per cent.
Entamoeba histolytica . 5 . ‘ a ‘ 9.7
E.coli. : z 7 i ‘ ‘ : i 45.9
Endolimax nana . m ¥ . : 12.1
Giardia intestinalis . é c i A < . 3-4
Chilomastix mesnili . 3 ; ‘ 23.2

In a later paper Smith (1919) eee his findings from a
larger series of cases examined at the Lancashire County Asylum
at Rainhill. His results were as follows:

Total No. of cases examined. . : ‘ é 504
Infected with: per cent.
Entamoeba sa ash : c 7 z @ a 4.2
E.coli. z % a # - ‘ 21.4
Endolimax nana “ ‘ x P . ‘i ; 3.0

Lodamoeba biitschlit . al
Giardia intestinalis . 3 : 3 Fi . 5
Chilomastin mesnili . . s . ‘ < - 6.
Trichomonas hominis 0

A few of the patients in this series were examined more than
once; but the figures given were calculated from the results
of only one examination per case—to keep them in line with the
others.

It should be noted that this series is not strictly comparable
with the others, as it includes a few persons who had been abroad.
It is stated that ‘only thirty-four of the five hundred and four
patients at Rainhill had, so far as could be traced, ever been
abroad’: but the findings for the ‘British’ cases alone are not
given, and as the individual histories are recorded for very few
cases, it is impossible to estimate—from what is published—
how far the inclusion of ‘foreign’ cases may have influenced
the results.

(5) Untversiry anp Scuoot Capers.

A very small series—unfinished—was examined by Matthews
and Smith (1919 a) from the University Platoon in an Officers’
Training Corps, and older boys from a secondary school near
Liverpool. All were males who had never been abroad—their
ages being from 15 to 19 years. Results (one examination per
ease) :

Total No. of cases examined . “ : . é 41

No. infected with :
Entamoeba histolytica : : : 3 ‘ 1
E, coli ‘ 5 7 . ‘ ‘ 11
Endolimax nana i
Giardia intestinalis 1

"48

24

The authors say of this series that their original object had
been ‘to examine a number of youths from a higher social class
and from better homes than the Army recruits whom we had
previously reported on. We can only say that infections of the
various protozoa exist among such persons.’

I shall not attempt to summarize at this point the many
other important facts brought out and discussed in the foregoing
reports. All who are interested in the subject with which they
deal will read the originals. There are, however, several matters
which require detailed consideration, and to these I shall return
in the next chapter. It will be more profitable, and much more
convenient, to consider these points after the newer results
obtained by the other workers have been given.

B. The Later Reports.

As already noted in the Introduction, the five investigators
working for the War Office Committee on Dysentery (see p. 13)
presented, in due course, reports on their work. They also (with
one exception) sent me back the cards—fully filled up, for the
most part—with which they had been supplied for the purpose
of recording their findings. I have thus been able to check the
reports by means of the cards, and in many cases I have added
relevant details from the latter when they were not given in the
reports themselves. I have also freely exercised my editorial
privileges in preparing these reports for press: for it has been
possible, and, indeed, necessary, to introduce a greater uniformity
of treatment cf the material than was possible to the writers of
individual reports—unacquainted as they were with the work
of one another. I have cast all the tables in the same form, and
eliminated or simplified a number of complicated ones when this
appeared desirable. J have throughout. removed everything
which appeared to me superfluous, and have endeavoured to
present the essentials as concisely as possible. I have also—as
I have, indeed, throughout the whole of the present work—
silently corrected the nomenclature of the protozoa to which
reference is made, when the names employed have not accorded
with current zoological usage. With these modifications, the
reports now presented are the work of the authors whose names
they bear. Remarks or additions of my own—which mostly
consist of supplementary information which I have copied from
the cards—are distinguished by being enclosed in square
‘brackets.

1. BrrmincHam Report.

By T. Goodey.

Faeces samples were obtained from civilians undergoing
treatment for phthisis at two sanatoria, viz. Salterley Grange
Sanatorium, Cheltenham, one of the Birmingham Corporation
sanatoria, and Cranham Lodge Sanatorium, near Stroud, a private.

25

sanatorium. Samples were sent in from 101 persons who had
never been abroad, and of these, 70 were residents of Birmingham,
and the remaining 31 were, for the most part, residents of places
in South Wales, Somerset, and Gloucester, and thus representative
of a more rural type of population than the 70 from Birmingham.
The examinations were made in the Research Laboratory in
Agricultural Zoology, Birmingham University.

Altogether 72 males and 29 females were examined. Three
samples of faeces from each were examined in all except three
cases, two of which were examined twice and the other only
once.

Practically all the individuals examined belonged to the
artisan classes. Entamoeba histolytica cysts were found in the
stools of' six persons, only one of whom (Case 10) had experienced
any previous bowel trouble.

The results in the case of the other intestinal protozoa are
see out in the following table, and call for no special remark

ere:

Total No. of cases examined ‘ ‘ ‘ r ‘ 101

Protozoa : No. of cases infected.
Entamoeba histolytica s a a <
Ett. F 5 . ‘ ‘ ‘ ‘ 2.
Endolimax nana
Iodamoeba biitschlit .
Giardia intestinalis .
Chilomastix mesnili .

HOR IO

[As the total number of cases examined in this series is 101,
it has not been thought necessary to present these results as
percentages. |

I am indebted to Dr. Robertson, Medical Officer of Health
for the City of Birmingham, for very kindly granting me
facilities to obtain stool samples from Salterley Grange Sana-
torium. To Dr. E. G. Glover, M.O. in charge of this sanatorium,
my very best thanks are due for the great interest which he took
in the work both in the collection and dispatch of the samples
and in obtaining the previous medical histories of those cases
carrying EF. histolytica. Through his keenness, too, he obtained
samples from patients at the Cranham Lodge Sanatorium, Stroud,
in the charge of Dr. Arthur H. Hoffman, to whom also my best
thanks are due for the interest taken in the work and for the
readiness with which he sent information about the carrier cases.

[The following additional particulars concerning the six cases
infected with E. histolytica are given on the cards returned from
Birmingham, and are added here as they contain interesting
information. |

Cases infected with E. histolytica.

Case No. Sex. Age. Occupation. Place of residence,
1 M. 15 Fitter’s assistant Birmingham.
10 M. 51 Engraver Birmingham.
62 M. 22 Fitter Bristol.
70 M. 183 Engineer Chard, Somerset.
82 M. 35 Munition worker Birmingham.
103 F. 42 Housewife Birmingham,

26

[The following information about five of these cases was
elicited by Dr. E. G. Glover (Cases 1, 10, 82) and Dr. A. H.
Hoffman (Cases 62, 70).]

Case 1.—Left school when 14 years old. Delivered milk
for about 8 months: since employed in about 20 different jobs.
Never any tools in mouth, and never repaired old clothing, &c.
Born in Birmingham, and has not been elsewhere save for one
short visit to a Shropshire village (where he drank tap-water),
and one to Bournemouth. Bowels regular as a rule: never
constipated. Had diarrhoea lasting one day in 1917, but never
passed blood. Has occasional flatulence after heavy meals. No
abdominal discomfort. Father a Birmingham man, who died
(aet. 45) of pneumonia. Mother a Birmingham woman. One
brother consumptive, no bowel trouble. No record of dysentery
in family. Has never been in contact with foreigners.

Case 10.—Born in Birmingham, where he has lived all his
life. Only away on holidays. In engraving industry (steel,
gold, &c.) since age of 18—not dusty work. Occasionally holds
steel tools in mouth, and does jewellery repairs for private houses.
Water-supply always municipal. Healthy boyhood: after 19
years chest troubles. Pleurisy at 22. Bowels: seemingly normal
till 19, when he had an attack of diarrhoea lasting 2 weeks in
midsummer. Free until following summer, when it recurred.
Occasional attacks till age of 40, when he went to hospital and
had ‘draughts’. Since then well to Christmas 1917, when he
had diarrhoea for a week, arrested by treatment. Has haemor-
rhoids, and is rather constipated as a rule. No special abdominal
pain during either constipation or diarrhoea, except colic. Liver
normal: no jaundice. Wife healthy, never abroad.

Case 62.—Born at Brislington, Bristol, where he has lived all
his life. Drinks tap-water. Has been a fitter for 8 years.
Does not put tools in mouth, and does not repair old clothes or
personal articles. Has had diarrhoea very occasionally, but not
lately. No blood or slime in stools. No members of family or
‘reas with bowel troubles. No foreigners have lived in his

ouse.

Case 70.—Born in Chard, Somerset, and has lived there all
his life. Drinks well-water. In present employment for 1 year.
Does not hold tools in mouth. Has not repaired old clothes or
personal articles. Has not suffered from diarrhoea or any bowel
trouble, nor has any member of his household. No foreigners
have lived in his house. ;

Case 82.—Born in Birmingham, and has lived there all his
life: never absent on ‘holiday for more than a few days. Has
always drunk tap-water. Cabinet maker and upholsterer from -
age of 14 to 17--chiefly doing repairs from public-houses, smoke-
rooms, and private houses (never bedrooms)—and used to put
tacks in his mouth. Polisher (metal) from age of 17 to 82.
Joined army in 1914. In training in England September 1914
to February 1915: then discharged with septic poisoning, &c.
Usual sanitary arrangements in army: in billets—cottages,

27

&e.—and drank well-water for 2 months. Not in contact with
dysentery cases, and never had diarrhoea himself. At age of
3-4 years he had looseness of bowels (hearsay evidence of
parents): since then no diarrhoea. But 6 years ago he had
so-called ‘catarrh of the stomach’ (? due to eating pork), which
lasted one week, with diarrhoea and abdominal pain—no blood
or mucus or straining—and has been quite well since. No
history of diarrhoea in parents, wife, or family. Never in contact
with foreigners.

[The following further information regarding the infections
of the 6 positive cases has been compiled from the cards. |

Case No. 1.—Cysts of E. histolytica present in stools in fair
numbers. Diameter 9-5 » to 12-5 w (in fixed and stained con-
dition). No other protozoa found.

No. 10.—Cysts in moderate numbers. Diameter 10 p to 12.7 p,
in stained preparation. No other protozoa found.

No. 62.—Cysts in moderate numbers, 12-13-8 in diameter.
Large numbers of Giardia. cysts also present.

No. 70.—Cysts in moderate numbers, 10-12 w in diameter.
No other protozoa found.

No. 82.—Cysts in moderate numbers, 12-5 to 14-84 in
diameter. Cysts of E. coli and Giardia also present in stools.

No. 103.—Cysts in fair numbers. Diameter 10-7 u to 12-2 p.
No other protozoa found. Stool examined only once.

2. Briguton REprorr.
By A. G. Thacker.

A small number of microscopic examinations of faeces of
civilians were carried out at the Central Laboratory, Kitchener
Hospital, Brighton, in August 1918 and again in June 1919.
Sixty-nine persons were examined in all. Most of these persons
were inmates of the Workhouse Infirmary, but a few were
patients in the Borough Sanatorium. None of the sixty-nine
persons concerned were suffering from any intestinal complaint.

The ages of the persons varied from nine years to over
seventy, and the sexes were almost equally divided. Forty-six
cases were examined once only, sixteen were examined twice,
three were examined three times, and the other four more often.
The intestinal protozoa were found during these examinations in
the following numbers:

Entamoeba histolytica . . : : 4 : 2 cases
E. coli : ‘; 7 ‘ H 15,
Endolimax nana 3 ? a ‘ ‘ 4
Giardia intestinalis . . : ‘ 7 ‘ 25
Chilomastix mesnili . $ , 4 r 4 yy

Certain particulars were obtained relating to the lives of the
persons concerned, and it was found that fourteen of the persons
had been abroad at one time or another, most of them to tropical
countries. Thus, one of the persons having Entamoeba histolytica

28

was the wife of a soldier and had been to India with her husband,
and had suffered from dysentery whilst there. The other person
carrying Entamoeba histolytica had never been abroad and had
never suffered from dysentery. He had been a butcher, but had
been in the workhouse infirmary about six years.

In the fifty-five persons who had never been abroad the
intestinal protozoa were found in the following numbers:

Entamoeba histolytica . ‘ ‘ : : 1 case
E.coli. 5 A . F . . 10 cases
Endolimax nana ‘ A , . : 5 455
Giardia intestinalis . z e a : : De oss
Chilomastia mesnili . “ : : ‘ : 3 yy

My thanks are due to Captain J. R. Dickson, R.A.M.C., officer
in charge of the Central Laboratory, for kindly arranging for the
work to be done under his supervision; and also to Dr. Forbes,
Medical Officer of Health for Brighton, to whom we were indebted
for the supply of specimens.

[In addition to the foregoing brief report, Mr. Thacker has
sent an account of two military patients investigated by him at
Brighton. These cases were studied with great care, and their
histories inquired into in considerable detail; but as both of
them had been abroad, they could not be included in the
‘British’ series. As the evidence shows, both were cases of
typical amoebic dysentery: but the evidence shows, further, that
they probably contracted this disease in England. There are,
moreover, indications of the way in which they may have
acquired their infections with Et histolytica. So little is known
at present about cases of English amoebic dysentery, and about
the manner of acquiring infection with the parasite, that no
excuse seems needed for publishing these two cases here in some
detail.]

Notes on two cases of amoebic dysentery probably acquired in
England.

Case 1.—This patient’s father was in the army. During the
Egyptian campaign of 1882 he had a severe attack of dysentery.
He never recovered from this dysentery, but had repeated
relapses, and died in 1890 of dysentery and Bright’s disease.
The present patient, who was born in 1884, developed dysentery
when a small child (about 2 years old), and it was surmised that
he had ‘caught it from his father’. He did not have it very
severely; but in the acute stage he passed about 20 stools
per diem with much pain in the region of the colon. After
this, all through his life, he had periodic severe relapses, four
to six times a year. He had 15 to 20 stools per diem in these
relapses, with severe pain. The patient states that he used
sometimes to see blood in his stools during these attacks, but
as a rule the bleeding was not profuse. “He grew up generally
delicate, and became a boot repairer. He joined the army in
1915, and while in the army had several of his usual rather mild

29

attacks of dysentery. He had a more severe attack at Albert in
December 1916—about 25 stools per diem, with blood and slime.
He was in hospital at Abbeville for nearly six months, and was
treated with emetine. After rejoining his unit in May 1917, he
had two more mild attacks, and then came home on leave in
November 1917. Whilst in England (his home is in Brighton)
he entered hospital for ulcers on his legs, and whilst in hospital
had another attack of dysentery and was transferred to the
2nd Eastern General Hospital, Brighton, where I first saw him
(March 1918). Z£. histolytica was found in his stools at the first
examination. He was treated first with emetine injections
(1 grain a day for 12 days), but remained positive during the
course, and cysts were afterwards found in his stools in great
numbers. He was then treated with emetine bismuth iodide
(3 grains daily for 12 days); but he again remained positive
during the course, and numerous cysts were passed afterwards.
As this treatment made him very ill, he was next treated with
‘Chaparro’—the usual 10-day course. Ten subsequent negative
examinations made over a period of nearly a month allowed him
to be passed on to the Dysentery Dépét at Barton as ‘negative’.
Here, however, he was again found positive at the third exami-
nation. He was then treated twice with emetine bismuth iodide
(at Barton)—each course lasting 16 days. After his second course
he was passed out of Barton as‘cured’. (He forgets exactly
how many negative examinations were made.)

This patient was infected with EF. coli, E. nana, and Tricho-
cephalus, in addition to &. histolytica. Save for his service in
France in the army, he had never at any time been abroad.

Case 2.—This patient had never had dysentery or even severe
diarrhoea before the War. He had, however, travelled a lot in
Europe—France, Belgium, Holland, Germany, and Spain. (Only
once in Spain, in 1902: never further south than Madrid.) He
joined the army in September 1916, when 39 years old, and went
to Aldershot about November 20, 1916. In Aldershot he shared
a room with five other men, one of whom had been in Mesopotamia,
and the other four in India. Several of these had had dysentery
out East. Patient’s battery and another battery used the same
latrine; and about December 10 a dispute arose between the two
batteries in regard to the cleaning of this joint latrine, with the
result that neither battery would arrange for the cleaning to be
done. The latrine remained in a dirty state for several days.
On December 13 my patient had a sudden attack of dysentery.
He was due to go on leave on December 15, so did not report sick,
but went home to Halifax. After he reached home he got rapidly
much worse, but was treated by his own doctor and had no labora-
tory diagnosis. He passed about 20 stools daily with much blood.
Returned to Aldershot in February 1917 and subsequently went
to France, where he had periodic severe attacks of diarrhoea.
He was invalided for trench fever in November 1917, and sent
to various hospitals. In January 1918 he went into training again
at Shoreham. His diarrhoea got worse, and he was invalided

(4181) AQ

30

into the 2nd Eastern General Hospital as an ‘ Enteritis’ case in
May 1918. I found him positive for E. histolytica on the first
test. He was then transferred to the Kitchener Hospital, and
treated first with emetine injections (1 gr. daily for 12 days).
This failed. He was then treated with emetine bismuth iodide
(usual 12-day course, 3 gr. per diem). This apparently succeeded.
Ten negative tests were made by me over a period of six weeks
following treatment, and he then passed successfully through
Barton Dépét as a ‘negative’ case.

3. Bristot Report.
By A. H. Campbell.

The material for examination was obtained from Stapleton
Workhouse, Bristol, and the Children’s Hospital, St. Michael’s
Hill, Bristol. The stools were examined in saline or iodine
solution in the usual way, and if necessary fixed and stained
preparations were also made.

This work would have been impossible without the very
careful collection of material by Dr. W. R. Norgate at the
Stapleton Workhouse and the Medical Officers at the Children’s
Hospital. I am much indebted to them for their assistance, and
also to Professor Walker Hall, M.D., for making the general
arrangements and for continual interest and advice. The work
was carried out in the Pathological Laboratory of the University
of Bristol.

Altogether, the stools of 213 adults (including all persons over
12 years of age) and 49 children under 12 were examined.
Repeated examination of the same case was not always possible—
owing to death or discharge from hospital. The number of
examinations made per case was as follows:

Adults (over 12). Children (under 12).
One examination 5 22 41
Two examinations at og 54 2
Three examinations 6 . 137 6
Total No. examined F » 2138 “49

[It was found on inquiry that 31 inmates of the workhouse
had been abroad, whilst particulars of 4 others were unobtainable.
If these 35 cases are eliminated from the series, the total number
of persons who had never been out of Britain was 227 (178 adults,
49 children). The protozoological findings in these 227 cases are
shown in the following table. |

Persons who have never been abroad.

Total No. of cases examined . ‘ : 227

Protozoa: No. infected. Percentage.
Entamoeba histolytica . . 7 08
Entamoeba coli . : F . 105 46.2
Endolimax nana ‘ ¥ » 15 6.6

Giardia intestinalis. . » 15 6-6
Chilomastix mesnili ‘ . 24 0.5

31

[Although the incidence of E. histolytica infection in the adults
and in the children was not very different, when the small numbers
examined are taken into account, there was a notable difference in
the two groups with regard to the other protozoa. This will be
evident from the following table.]

Adults. Children.
Total No. examined 178
Percent. infected with :
E. histolytica . * ‘ ‘ 3.3 2.0
E.coli. * s w ‘ . 53.9 18.3
E. nana . F 7.8 2.0
G. intestinalis ‘ : ‘ P 3.9 16.3
Ch. mesnili . ‘ 3 _ - 13.4 0-0

[The Stapleton Workhouse series included a number of mental
cases (68 in all). The figures obtained for all of the inmates of
this institution (213) were:

Mental. Non-mental.
Percent. infected with ZL. histolytica “ 2.94 2-75

It is thus evident that the ‘mental’ and ‘non-mental’ cases
were not appreciably different, so far as their degree of infection
with EF. histolytica was concerned.|

[The following are particulars—compiled from the cards—of
the 7 persons who had never been abroad and in whose stools
cysts of E. histolytica were found. ]

Case No. Sex. Age. Occupation. Other protozoa found.
32 M. 52 Porter. Nil.
78 M. 74 Sanitary worker. E. coli.
103 M. 65 Lithographic writer. EB. coli ; Chilomastix.
114 M. 3 Nil (infant). E, coli; EB. nana.
198 Fr 44 Nil (mental case). E. nana.
207 F. 49 Nil (mental case). E. coli ; Chilomastix.
2 237a M 14 Nil. E. coli.

[Case No. 82 had recently had an attack of typhoid, whilst
No. 78 is stated to have suffered from dysentery 6 years before.
The remainder gave no history of dysentery, diarrhoea, or other
intestinal ailment. ]

In all these cases E. histolytica was found in the encysted
condition in the stools. The cysts were all of races ranging from
11-5 w to 12-8 in average diameter. None of the races of
E. histolytica with smaller cysts were met with.

Out of the whole series of cases (213 adults, 49 children),
22 (all adults) had a previous history of dysentery. Only one of
these was found infected with EL. histolytica. But 50 adults and
16 children had suffered at some time from chronic diarrhoea,
and in none of these were the cysts of the parasite detected.

4. LEEDS AND SHEFFIELD Reports.
By Muriel M. Nutt.

The following are the results obtained from the examination
of the stools of civilians with a view to ascertaining what
percentage of the normal population of this country is infected

A 10

32

with Entamoeba histolytica and other intestinal protozoa. The
majority of the examinations were done at Leeds on specimens
obtained from patients at the General Infirmary and Workhouse
Infirmary. A number of specimens have also been obtained from
the Royal Hospital, Sheffield.

Acknowledgements.—I am extremely indebted to Professor
M. J. Stewart for the trouble he took in getting me specimens
from the Leeds General Infirmary, and for his kindness and the
interest he took in this work. I also wish to thank Dr. Allen
of the Leeds Workhouse Infirmary for allowing me to obtain
specimens from the workhouse patients, and Major Jamieson for
the facilities he gave in starting the work at the East Leeds War
Hospital. To Dr. Gruner I am indebted for the specimens from
the non-dysenteric military patients at Killingbeck and East
Leeds War Hospitals (see Appendix, p. 36). At Sheffield my
work at the University has been greatly facilitated by Professor
Sholto Douglas’s kindness and help. I must also express my
gratitude to Dr. Hall for his kind assistance in obtaining speci-
mens for me from the Royal Hospital, and to Dr. Naish for those
obtained from the Children’s Ward of the same Hospital.

Technique.—The technique employed has been exactly similar
to that used in the routine examination of the military cases. Two
preparations were made from every specimen, from different parts
of the stool, the preparations being made in normal saline or
Weigert’s iodine solution.

(a) Leeds.

Two classes of civilians have been examined—adults, and
children under twelve years old. The following table gives the
percentages of protozoa found in the total number of persons
examined :

Total No. of persons examined . ‘ x é ‘é 461

Percent. infected with : Adults (333). Children (128).
Entamoeba histolytica 1.2 1.6
E.coli. ‘ a ‘ 21.0 13.3
Endolimax nana i ‘i 7 2.4 4:7
Iodamoeba, biitschlii * 4 0.3 0.0
Giardia intestinalis . é P 3-6 39.8
Chilomastix mesnili . ‘ . 1214 7.8
Trichomonas hominis . ‘ 4 0.3 0.0

It was necessary to find out how many of the 461 civilians
examined had ever been abroad. In the next table, therefore,
these are divided into different groups, A, B, C. In Group A
none of the 210 adults had ever been out of this country, and of
these 3 were infected with & histolytica. All the 128 children
examined were found to belong to Group A, and of these 2 were
passing J. histolytica cysts. Group B consists of those persons of
whom it was impossible to ascertain with certainty whether they
had ever been abroad. As far as could be gathered from the
sisters in the wards and other indirect sources it seemed very

33

unlikely, but as information could not be obtained from the
patients themselves it seemed best to place them in a separate
class as uncertain. In Group C are placed 31 cases who have
been abroad at some period of life. One out of these was positive
for E. histolytica. The small number of persons in this group
necessarily makes the percentage of positives higher here than
in the other two:

Group A.

Adults. Children. Group B. Group Cy
Percent. infected with : (210) (128) (92) (31)
Entamoeba histolytica. 1.4 1.6 0-0 3.2
E.coli. ‘ é . 21.9 13.3 22.8 9.7
Endolimax nana 2.9 4.7 a. 3.2
TIodamoeba biitschlit 0:0 0.0 11 0-0
Giardia intestinalis . 3-8 39.8 4.3 0.0
Chilomastix mesnili » 12.4 7-8 8.7 12.9
Trichomonas hominis 0.0 0-0 1.1 0.0

Notes on the Cases infected with E. histolytica.

Case I. 1. Woman of 69. Has never been out of the country.
Was formerly in a mill, now does charing. Place of residence,
Leeds. Has had occasional attacks of diarrhoea, both lately and
in the past. This was a case showing precystic (‘minuta’)
amoebae, average diameter 12-13 ». (Also infected with E. colt
and Giardia.)

Case I. 2. Man of 67. Never been out of this country.
Residence, Castleford. Never troubled with diarrhoea or any
other intestinal complaint. Cysts few, with an average diameter
of 13 p. (Also infected with EL. coli.)

Case W. 3. Man of 66. This man was paralysed and had
great difficulty in speaking and making himself understood, but
as far as could be gathered it seemed very unlikely that he had
ever been abroad. Occupation, gardener. Residence, Leeds. No
history of dysentery or diarrhoea. Cysts few, 12-13 y» in diameter.
(Also infected with F. coli.)

Case I. 4. Woman of 72. Fifty years ago had been in New
York. Used to take in sewing as an occupation. Residence,
Leeds. Never had any trouble with diarrhoea nor a day’s illness
in her life until she entered the Infirmary for eye treatment.
Cysts few, average diameter 7-8 ». (No other protozoa found.)

Case I. 384. Boy of 11. Has never himself been abroad, but
parents are Russian Jews. Never troubled with diarrhoea, and
seemed quite healthy and sturdy. Was in the Infirmary for
treatment of his eyes. Cysts few, average diameter 12 yp. (Also
infected with & coli, E. nana, and Trichuris.)

Case W. 335. Girl of 10. Tubercular. Never been out of the
country. Had no trouble with diarrhoea. Residence, Leeds.
Parents have never been abroad. Cysts few, 13 » in diameter.
(Also infected with £. coli, Giardia, and Chilomastiz.)

34

Number of examinations.

The majority of the cases could be examined only once, but
a certain number were examined two or more times. Three out
of the four adults who were positive for E. histolytica were
discovered at the first examination, and one at the third examina-
tion. Among the children, both positives were found at the first
examination. The following table shows the number of examina-
tions made per case for the whole series :

Adults. Children,
No. examined once ¥ ‘ 4 ~ 275 103
45 e twice . ‘ ‘ 3 * 39 20
45 a 3 times P ‘ 4 ‘ 17 4
” ” B55 . é < 1 1
” ” 7 ” . . . 1 0
333 128

Sex and Protozoal Infection.

In the following table all the adults examined (333) are
divided into males and females, so that a comparison between
the incidence of protozoal infections in the two sexes can be
made. It will be seen, however, that there is very little

difference between them in this respect:
Adults.
Males. Females.
Total No. examined , 172 161

Percent. infected with :

E. histolytica 12 1.2
E. coli 22.5 20.5
E. nana . 2-9 1.9
I. biitschlit 0.6 0.0
G. intestinalis . 3.5 3.7
Ch. mesnili 10.5 12.4
T. hominis 0.0 0.6

Age, Occupation, Residence.

From the above tables age seems to have little or no bearing
upon the protozoal infection except possibly in one case, that of
infection with lamblia (Giardia intestinalis). Children appear to
be infected in greater numbers than adults. This is shown in
the first table, where for children the percentage is 39-8, while
for adults it is 2-8 only. Two groups of children have been
examined, and in each group the lamblia infection is higher
among them than among adults taken from the same institution.
The higher percentage was found among the Workhouse children,
where it reached 48-8 per cent., as against 3-6 per cent. found in
adults from that institution. Among the children examined from
the Leeds General Infirmary the percentage was 23-9 compared
with 3-9 found in the corresponding adults.

The age at which children were found to be infected in the
greatest numbers was between one and four years.

There does not seem any relation between occupation and
infection, neither does the place of residence, whether in a large

35

town or small country village, seem to have any connexion with
the protozoal infection. It should be noted, however, that the
majority of the cases examined at Leeds are resident in the
poorer parts of the city.

(b) Sheffield.

From January to May, 1919, I examined the stools of 174
civilians at Sheffield. Of these, 117 were adults and 57 children—
all inmates of Sheffield Royal Hospital and Royal Infirmary. On
investigation it was found that 6 of the adults had been abroad.
These have been eliminated from the series, so that the results
summarized in the following table were obtained from 168 cases
(111 adults, 57 children) who had never left England. Of these
cases, 84 adults and 39 children were examined once only—the
remainder twice, thrice, or more often (only 5 cases more than
3 times). The table corresponds to that given for the Leeds
civilians, and shows the percentages of the various protozoa
found:

Total No. of persons examined : : F 168
Percent, infected with : Adults (111). Children (57).
Entamoeba histolytica . a i 1.8 5.3
E. colt ‘ ; : a . 26.1 24.6
Endolimax nana ‘ r ‘ 6.3 7.0
Giardia intestinalis 7.2 15.8
Chilomastix mesnili 5.4 5.3

No infections with Jodamoeba or Trichomonas were found in
this series.

[It may be noted, however, that several infections with
Trichuris were found at both Leeds and Sheffield. The total
number of persons found to be passing ova of this worm in their
stools was 5, or approximately 1 per cent. of the whole series
of 506 persons who had never been abroad.]

The total number of persons found to be infected with
E. histolytica was 5 (2 adults, 3 children). Below are further
notes on these positive cases—none of whom had, of course, ever
been out of the British Isles.

Case 1.—Boy of 17. Has never suffered from dysentery or
persistent diarrhoea. Residence, Sheffield. Occupation con-
nected with grinding stone. Cysts few, diameter 12-18 p. (Also
infected with & coli and Giardia.)

Case 2.—Man of 80. Butcher, residing in Sheffield. Has
never suffered from dysentery, diarrhoea, or any other intestinal
trouble. Cysts few, 12-13 yw in diameter. (No other protozoa
found.)

Case 3.—Boy of 18, living in Sheffield. Has never suffered
from dysentery, but occasionally has slight diarrhoea—never
severe. Cysts ca. 12 u in diameter, few. (Also infected with
E. coli and Giardia.)

Case 4.—Girl of 8, living at Conisborough. Has never been
troubled with dysentery or diarrhoea; but whilst in hospital had

36

bowels moved 2-8 times a day. In hospital for tuberculosis of
knee. Father a soldier, in France. Cysts few, ca. 12 yw in
diameter. (Also infected with E. coli and Giardia.)

Case 5.—Boy of 9, living in Sheffield. Has never suffered
trom dysentery or diarrhoea—and appears perfectly healthy. In
hospital for amputation of leg. Cysts few, belonging to two
different races—ca. 7 w and 12 yw in diameter. (Also infected
with £. coli.)

Summary and Conclusions.

At Leeds and Sheffield I examined altogether 506 members
of the civil population who had never been abroad. These
consisted of 321 adults and 185 children. Out of this number
10 individuals were found to be infected with Entamoeba histo-
lytica—that is, approximately 2 per cent. A higher rate of
infection was found in children than in adults, the figures being :

5 out of 185, or 2-7 per cent. of children infected with EZ. histolytica,
5 yy 5 821, ,,1:5 4, 4, adults ” ” ” ”

The other intestinal protozoa were also found more frequently
in children than in adults. At Leeds 32-7 per cent. of adults and
50-8 per cent. of children were found infected with protozoa other
than F. histolytica. The most striking difference was in the rate
of infection with lamblia (Giardia intestinalis), the figures being :

Leeds. Sheffield.
Adults. Children. Adults. Children.
Percentage . 3:8 39-8 7.2 15:8

The percentages given are all: probably too low, since in the
majority of cases they are calculated on the result of one
examination only.

APPENDIX.
Non-dysenteric military patients.

In order that a comparison might be made with the foregoing
results obtained from civilians, a certain number of non-dysenteric
military patients were examined during July 1918. The majority
were nephritis cases at Killingbeck Military Hospital, Leeds, the
remainder being surgical cases at East Leeds War Hospital, and
about five were from the Leeds General Infirmary. The results
are tabulated below :

Total No. of cases examined r je F ‘ ‘ 71

Protozoa : Percent. infected.
Entamoeba histolytica . ; 7 i ‘i ; 7:0
Entamoeba coli . “ ‘ 3 P 40-8
Endolimax nana ‘ * 4 . 11:3
Todamoeba biitschlii . i ‘ i ; ‘ 4-2
Giardia intestinalis i ‘ ‘ ‘ 2 : 85
Chilomastix mesnili : : ‘ 4-2

37

Notes on the cases carrying K. histolytica.

Case M. 462, had been in France 24 years but never in the
East. Had no history of dysentery or diarrhoea or any other
intestinal trouble. Surgical case. Cysts 7 in diameter.

Case M. 463, had been in France, South Africa, Ceylon, Singa-
pore, but never had dysentery, diarrhoea, or any other intestinal
ailment. Nephritis case. Cysts 7-8 » in diameter.

Case M. 464, had been in France but not in the East. Slight
diarrhoea in France about a year ago. Nephritis case. Cysts 10 p.

Case M. 465. Trench fever case. Untortunately, this patient
was sent away before any information could be obtained from him.
Had certainly been in France. Cysts 12 p.

Case I. 466. Discharged soldier in Leeds General Infirmary.
Had been in France but not in the East. Never had a day’s
illness in his life before he was wounded in France in 1917.
The majority of the men in his regiment in France had suffered
from dysentery. Cysts 12 y.

Thus it appears as if about 7 per cent. of the military patients
who are sent to hospitals for diseases other than dysentery are
carriers of Entamoeba histolytica.

5. Reaping Report.
By R.C. McLean.

The following examinations were carried out in the labora-
tories attached to the Royal Berkshire Hospital and the Reading
War Hospital.

Those examined were, with few exceptions, inmates of either
the Royal Berkshire Hospital or of the Park Isolation Hospital,
Reading. I wish to acknowledge my indebtedness to the medical
staff of those institutions for permission to conduct the investiga-
tion, and to the Matrons and Sisters for their kind help in
collecting and forwarding specimens for examination.

The total number of persons examined was 140, divided thus :

Males 57.
Adults | Females 60.
Children under twelve 23.

Of these, 20 (15 males, 5 females) gave particulars of residence
abroad. Among these were 7 ex-soldiers with a record of service
in France during the War. None of them had dysentery recorded
in their medical histories. [The total number of persons who had
never been abroad was thus 120. The stools of each were examined
only once. |

The total number giving an account of previous intestinal
disorder was 4, of whom the following are the particulars :

M.58. Carcinoma of rectum in July 1918. No residence abroad.
No protozoa.

38

M. 81. Dysentery in Reading 1896. Visited China 1850. No
protozoa. te

F. 26. Dysentery in Reading 1913—‘slight.’ Visited the West
Indies 1912. No protozoa. t

F.115. ‘Clinical Dysentery’ at date of examination. A military
nursing sister. No residence abroad. No protozoa.

Below is a summary, in tabular form, of the results of the
protozoological examinations of the stools of the persons who had
never been abroad.

Total No. of cases examined é 7 ¥ i . 120

Protozoa : No. of cases infected. Percentage.
Entamoeba histolytica ‘s 5 3 ‘i : 2.5
Entamoeba coli - é é P 20 ; * 16.6
Endolimax nana. % c F 10 ‘ é 8.3
Giardia intestinalis 3 ; 13 ; ‘ 10-8
Chilomastix mesnili P ; ‘ 1 : 5 0.8

It is interesting to note that the three cases in which cysts of
E. histolytica were found were all females in the same ward of
the Berkshire Hospital. Their ages and occupations were:

Case No. Age. Occupation.
6 66 Nil (house duties only).
15 19 Domestic servant.
38 18 Laundry maid.

As two of these—Nos. 15 and 38—were young girls in employ-
ment in villages, they may be regarded as liable to contact with
returned soldiers. The third was a woman living in a good
residential district of Reading. None had any trace of intestinal
disorder present or past, but they were all three evacuating the
cysts in large numbers. ;

[From the entries on the cards, it appears that the cysts of
Case 6 measured 9-18 » in diameter; those of Case 15, 8-11] p.
The diameter of the cysts of Case 38 is not recorded. It may be
added that Cases 15 and 88 were also infected with EF. nana, and
Case 6 with Giardia.]

Finally, it may be noted that worm eggs were found in the
stools of 11 cases (Trichuris trichiura, 7; Ascaris lumbricoides, 8 ;
Oxyuris vermicularis, 1).

39

CHAPTER IV. SUMMARY OF ALL REPORTS, AND DIS-
CUSSION OF CERTAIN POINTS OF PARTICULAR
INTEREST.

In this chapter I propose to combine and discuss the results
obtained by all the workers concerned in the present investigation.
I shall begin with a consideration of the incidence of infection
with the various protozoa studied.

A. The Incidence of Protozoal Infections in Persons who have
never left Britain.

There is now a fairly large accumulation of statistics bearing
on this subject, and it 1s therefore now possible to estimate the
probable incidence of several different protozoal infections with
some precision. In order to arrive at a just estimate of the
results as a whole it will be necessary, in the first place, to add
together the findings recorded in the several Reports.

The findings of Smith and Matthews are mostly presented in
the form of percentages; and I have therefore worked out their
actual figures in order to be able to combine them with those of
the later workers. I have thought it necessary, for the present
purpose, to exclude the results recorded by them for asylum
patients. The people of this category are in several ways not
fair samples of the population, and there is reason to suppose
that their habits and mode of life are conducive to the acquisition
of intestinal infections to an abnormal extent. Excluding, there-
fore, the mental cases examined by Matthews and Smith (1919 a)
and Smith (1919), I have obtained the following figures from all
the Reports published by the Liverpool workers:

Protozoa !
wae.

Cases. Total No. E.h. E.c. Ein. Ib. Got. Chem.
Civilians, Royal Infirmary . 450 7 #30 11 1 Qf 7
Army Recruits. - 1098 62 200 60 5 77 2
Children ‘ F i 548 10 61 15 1 77 #10
Cadets . ‘ P " 41 1 11 Y @ 1 0

Grand total . 2137 80 302 87 7 182 19

This table gives the actual numbers of persons found infected
with intestinal protozoa in the four series of cases investigated by

'™ In this and the two subsequent tables the following abbreviations are used for
the names of the intestinal protozoa which come into consideration :
E.h, = Entamoeba histolytica.

E. ce. = Entamoeba coli.
E.n, = Endolimax nana
I.b

. b. = Lodamoeba biitschlit.
G. i. = Giardia intestinalis.
Ch. m. = Chilomastix mesnili.

40

Matthews and Smith: but it must be remembered that the findings
are based throughout on the results of only one examination per
case. None of the 2,187 persons in the whole series had ever been
abroad.

If we now take the results of the newer Reports, given on
earlier pages, and express them in the same way—converting
percentages into actual numbers as before, when necessary—we
obtain the figures shown in the following table:

Protozoa.

Cases at TotalNo #.h Ean Ein. Lb Gi. Chim.
Birmingham. : 101 6 28 7 1 5 1
Brighton . < 55 1 10 4 0 2 3
Bristol * : : 227 7 105 15 0 15 24
Leeds and Sheffield . 506 10 106 23 0 76 45
Reading. : 3 120 3 20 10 0 13 1

Grand total . 1009 27 =—.269 59 1 111 74

If we add these findings from 1,009 individuals who have
never been abroad to those from the 2,187 similar cases in the
Liverpool series, we obtain the following results :

Protozoa.

Cases, Total No E.hk Ec Ein. Ib. Git. Chim.
Liverpool (4 series) 2137 80 302 87 7 182 19
Six new series . . 1009 27 =269 59 1 111 74

Grand total . 3146 107 571 146 “8 298 98

Percent. 3-4 18-1 4:6 0.25 9.8 29

These final percentages, based on the records obtained from
the examination of over three thousand individuals—men, women,
and children—who have lived all their lives in Britain, give us
material for making an approximately correct estimate of the
extent to which the indigenous population of these islands is
infected with intestinal protozoa. But they cannot be accepted,
as they stand, as correct ; and for the following reasons.

The greater part of the series (over 2,000 persons) is composed
of the Liverpool cases. These were all examined but once apiece,
and they thus form—in this respect—a homogeneous series. The
other series, however (over 1,000 cases, or roughly. one-third of
the whole), consist of persons examined a variable number of
times each, and consequently the whole series is not homogeneous
in respect to the number of examinations made per case. It is
well known—from the figures already collected and published by
myself (1917) and others—that the number of infections found
in any series examined depends upon several factors: and one of
the most important of these is the number of examinations made
per case in the series. (I leave out of account now the other
factors—such as the competence of the examiner, the time taken
in making the examination, &c.—since there is no reason to

41

discuss these questions here. All the examiners whose work is
under consideration were specially trained for this work, and not
employed in it until I was personally satisfied of their compe-
tence. They all used similar methods, and may, I think, be
trusted to have exercised due care and diligence.) The number
of examinations made per case in the new series is roughly as
follows:

In the Birmingham series (101 cases), all but three cases were
examined thrice each. At Brighton (55 cases), most cases had
only one examination, but a few two or three. At Bristol, about
a half of the 227 cases studied had three examinations apiece, and
the rest one or two. The Leeds and Sheffield cases (338 and 168
cases respectively) mostly received one examination each, but a’
number received two or more. The 120 cases at Reading were
examined only once each. It is thus evident that the majority
of the cases in the whole series received but one examination
apiece; though a significant proportion received two or three, and
a negligible number more than three.

Now from figures which I have published elsewhere (1917),
from those recorded by the Liverpool workers and others, and
from those which I have accumulated since, it is clear that if any
series of cases is examined only once apiece, the number of
infections found is very considerably less than that which actually
existed. The errors due to deficient examination are not easily
determinable with precision ; but it is probable that, if the series
examined is sufficiently large, they are approximately of the
following order of magnitude: A series of cases examined once
apiece may be expected to disclose about one-third of the infections
actually present. The number of infections found will, at all
events, almost certainly be less than one-half of the real number.
The error for a series examined thrice per case is more easily
determined: and it is probable that, in such a series, between
one-half and two-thirds of the actual number of infections will
have been detected.

From these considerations it is clear that the percentages
given in the last table—since they are based, for the most part,
on series examined only once per case—must be multiplied by at
least two, or even by as much as three, in order to obtain the true
incidence of infection. To multiply by two would almost certainly
give too low a value, since a relatively small number of cases
received more than one examination ; but if we multiply by three,
we shall run the risk of obtaining too high a figure, since this
would be the factor appropriate to a series examined throughout
only once apiece. It is not at present possible to deal with findings
of this sort with great mathematical accuracy, but it is probably
safe to assume that the true figures lie between the limits which
can be approximately determined in this manner. I believe,
therefore, that the following figures give a fair estimate of the
true incidence of infection with the various protozoa, as indi-
cated by the minimal actual findings exhibited in the preceding
table:

Estimated percentage

Protozoon : incidence.
Entamoeba histolyticu e P P 7—10
Entamoeba colt Z ‘i 4 . 86—54
Endolimax nana . 3. A ° ‘ 9—13
Iodamoeba biitschlit 4 ‘ ‘ . 05 —0.75
Giardia intestinalis x F . - . 18—27
Chilomastix mesnili : * a F Fi 6— 9

It is now necessary to consider each intestinal protozoon in
greater detail, since there are special points of interest connected
with each and these have hitherto been omitted. I shall begin
with Entamoeba histolytica, which is the most important, and
which must therefore be considered in greatest detail.

1. Entamoeba histolytica.—It is clear that infections with this
protozoon are by no means uncommon in the resident population
of Britain. At least one carrier of this parasite has been found
by every worker who has taken part in the present investigation.
It has been demonstrated that 3-4 per cent. of examined persons
who have never been abroad (over 3,000 cases) are infected ; and,
as already stated, this probably indicates that some 7 to 10 per
cent. of these individuals actually harboured the parasite.

If it be permissible to generalize from these findings, for a
relatively small number oF cases, to the population as a whole,
then it appears that the people of these islands are infected to
a noteworthy extent—an extent, at any rate, which was quite
unsuspected until recently. It may, of course, be objected that
such generalization is not yet justified. The sample examined is
small: it may not be representative. On the other hand, it may
be remarked that the sample, though small, is not. very small;
and there is no obvious reason why it should not constitute a fair
sample—unless it be that it consists mainly of persons belonging
to the lower grades of society. It must not be forgotten, however,
that among the higher grades it becomes increasingly difficult to
find persons who have never been abroad, and who have therefore
only been exposed to infection at home. When this is borne in
mind, it appears not improbable that the entire population—
including all who have and all who have not been abroad— would,
if subjected to examination, prove to be even more heavily
infected with L. histolytica than the figures here recorded seem
to indicate. There seem no good grounds, at all events, for sup-
posing that the incidence for the total population is less.

The first indigenous case of E. histolytica infection recorded in
Britain is probably that of Dickinson (1862), though the diagnosis
rests on indirect evidence! The case of Saundby and Miller
(1909) appears to be the firstin which £. histolytica was actually
seen,” and the case described by Wenyon (1916) was apparently
the earliest recognized carrier showing cysts in the stools. The
later cases, described by the Liverpool workers and others, belong
almost entirely to this class—more or less healthy persons (carriers)
showing no clinical signs of disease due to their infections.

1 See p. 17. 2 See p. 19. 5 See p. 7.

43

It is certain, from the morphology of the organism and its
pathogenicity to the cat—-and sometimes to human beings—that
the amoebae and cysts found in British subjects really belong
to the species known as Kntamoeba histolytica—already familiar
as the ‘cause’ of amoebic dysentery and hepatic abscess in the
tropics. It has been shown (Wenyon and O’Connor (1917),
Dobell and Jepps (1918), &c.) that there are different strains of
this species, distinguishable by the dimensions of their cysts.
No detailed study of the strains found in British infections has
yet been made: but it is clear, from the measurements recorded
by several workers (see Chapter ITI), that similar strains exist in
Britain. The commonest—as in the case of the ‘tropical’ infec-
tions—appear to be those with cysts measuring 7-9 uw or 12-13 yp
in mean diameter; but there is not yet sufficient evidence to show
the relative frequency of the various strains in Britain.

Up to the present I have considered the incidence of E. histo-
lytica infection in Britain en bloc—without distinction of age,
sex, locality, or occupation of the infected individuals. Something
on each of these heads must be added here.

Age.—The age at which infection with EL. histolytica may be
first acquired has not yet been established with certainty, but it
is undoubtedly very early. The largest series of children
examined are those of Matthews and Smith (1919), who examined
548, and of Miss Nutt, who examined 185. The first series showed
that 1-8 per cent. were infected with E. histolytica, the second 2-7
per cent.

Matthews and Smith (1919) state that ‘among fifty children,
under one year of age, no infections were found’; but one infec-
tion with HE. histolytica was discovered by them ‘in a girl just
three years of age’. Thisis probably the youngest case in all the
series, but Mr. Campbell has recorded (p. 31) another E. histolytica
infection in a child of 3; and it may be recalled that Moore’s
patient (1881) died—apparently of an amoebic abscess of the liver
—at the age of 34 years. It is possible that in the case recorded
by Mr. Thacker (p. 28) the patient contracted amoebic dysentery
when only two years old.

There is now definite evidence that infections with intestinal
protozoa may be acquired during the first year of life (cf. Giardia,
p. 52); and, although such early infection has not yet been
observed in the case of E. histolytica, there appears to be no
reason to suppose that it behaves, in this respect, differently from
the other common intestinal organisms.

Infections with E. histolytica—and all other intestinal protozoa
—appear to be remarkably persistent, and it is probable that when
an infection is once acquired it lasts, in most cases, forthe rest of
life. (Cf. Wenyon and O’Connor (1917), Dobell and Stevenson
(1918).) The longer a person lives, the longer he is exposed to the
risk of becoming infected; and consequently one would expect
that, ceteris paribus, older people would show a higher degree of
infection than younger. This appears to be true. Matthews and
Smith have given the following figures bearing on this point:

44,

Age of Cases. No. examined. Percentage of £. histolytica.
1— 5 275 1
5—12 223 3.1
circa 18 1098 5-6

I am not sure whether these authors accept this interpretation
of their figures, for they appear to believe that some intestinal
infections may be commoner in children than in adults. This
supposition is linked with their hypothesis that protozoal infec-
tions of the intestine do not persist indefinitely, but tend to die
out in the course of time. They have not been able, however, to
obtain any direct or conclusive evidence of this, and there are
many observations which are not consistent with such a belief.
It must be noted here, further, that the above figures are selected,
and it is possible to select others which might lead to a different
conclusion. The numbers constituting most of their series are
comparatively small, however, and the error inherent in asystem
of only one examination per case is large. And consequently
when results such as those recorded by Miss Nutt (p. 36) are
considered—she found 2-7 per cent. of 185 children and only 1-5
per cent. of 821 adults infected with EH. histolytica—it is by no
means easy to draw certain conclusions from them. It is at least
debatable whether these findings indicate—as they might seem
to at first sight—that the children were more heavily infected
than the adults: and on other grounds such a generalization
appears to me unwarranted.

Sex.—In several series the cases have been sorted into sexes,
and the findings presented for the two classes separately. The
results have been consistent throughout, and show clearly that
E. histolytica occurs in males and females with equal frequency.
It will be unnecessary to recapitulate all the findings here: an
example will suffice. Miss Nutt, in the Leeds series, found 1-2
per cent. of adult males infected, and the same percentage of
adult females. Other series gave comparable results, and
Matthews and Smith have already concluded that the distribu-
tion of £. histolytica—and other intestinal protozoa—is ‘irre-
spective of sex’.

Occupation.— Matthews and Smith (1919) note that ‘some of
the results we have obtained seem to indicate that there may be
occupational differences in the incidence of infection’ with /
histolytica. They give the occupations of a number of the cases
which they studied, and these have been recorded also for most.
of the individuals in the newer reports printed in the previous
chapter. From all the records—including those of Baylis (1919),
and others already printed elsewhere—I have been able to collect
information concerning the occupation of one hundred persons
found to be infected with EF. histolytica in Britain. Not one of
these had ever been abroad prior to the time of examination. I
have purposely excluded from this series all children under
12, and patients in lunatic asylums. On analysing and classify-
ing these cases I obtained the following list :

45

A
°

e
S| et
|| Sl OHHH RH HH HED DN DDN WWOWRAR ROO OWAS

Occupation.
Miners . : P
Engineers, mechanics, &c.
Clerks, shop assistants, &c.
Housewives, domestic servants, &c.
Dock labourers, &e. . é : .
Farm labourers
Metal workers .
Spinners and weavers
Carters . :
Railwaymen, porters
Stone-workers, &. .
Labourers
Butchers .
Glass-workers .
Chemical workers .-
Carpenters, &e.
Bootmakers . ‘
Packers, warehousemen .
Schoolboys
Sanitary worker
Fisherman
Tailor
Gardener.
Grocer
Greengrocer
Miller
Baker ‘ ‘ ‘
No occupation (paupers)

Total

I give these figures for what they may be worth. They do not,
unfortunately, give us any indication of thg relative frequency
of infection among different classes of workers: but they are of
some interest in other ways. For example, the fact that E
histolytica occurs among domestic servants, bakers, butchers,
grocers, and other persons who habitually handle food, suggests
possibilities which cannot be ignored in considering the spread of
infection through the community. (Cf. p. 54 infra.)

On general grounds one would expect E. histolytica and other
intestinal protozoa to occur most frequently among people who
live under the most insanitary conditions. Prompt and efficient
disposal of faeces, and great personal cleanliness, would certainly
limit the spread of infection. It is scarcely surprising to find
that farm hands and dockers are infected, and nobody is likely to
be astonished at seeing a‘ sanitary worker ’in the above list. Itis
unfortunate that no figures are available to indicate the incidence
of infection among these various classes, and among groups of
persons belonging to higher social strata. It will be remembered
that practically all the persons hitherto studied belong to the
labouring and artisan classes; and consequently all the carriers
found are of the same status.

The large number of miners in the list will be noted, and this
record is of particular interest. The infected individuals were
mostly found by Matthews and Smith in a series of colliers. In
this series, consisting of 78 men, no less than 10, or 12-8 per cent.,
were found to be infected with E. histolytica. All the infected

46

individuals came from the South Wales coalfields. Although the
series is small this percentage is remarkably high, when it is
remembered that the stools were examined only once apiece. It
is probably too high to be without significance, and appears to
indicate that miners are infected to a greater extent than many
other classes of the community: which might, indeed, have been
expected, since the localization and spread of some other parasites
in mines is already well known.

The high rate of infection with E. histolytica found among
lunatics should also be noted here. Atoneasylum Matthews and
Smith (1919 a) found 9-7 per cent. of the inmates infected, as a
result of making only one examination per case. This isa high
rate, but not sohigh as a previously published record for the same
asylum appeared to indicate (Yorke, 1918). This series well
illustrates the possible errors in small samples. In the first
report, when only 46 cases had been examined, no less than 19.5
per cent. were found infected with L. histolytica. Later, when
207 cases had been studied, this percentage fellto9-7._ At another
asylum, where he examined 504 patients (once apiece), Smith
(1919) found only 4-2 per cent. infected. Campbell (supra, p. 31)
found 2-94 per cent. of ‘mental cases’, in a workhouse, infected
with E. histolytica—as compared with 2-75 per cent. in a larger
series of ‘non-mental’ cases in the same institution. Such figures
as these do not justify the conclusion that all lunatic asylums are
hotbeds of E. hastolytica infection.

In considering the possible correlation of &. histolytica infection
with particular occypations or modes of life, it is important to
remember that the parasite occurs in children—even in those of
very tender age. When this is borne in mind, and the results of
the investigation of several families by Smith and Matthews +
and Kuenen? are also taken into account, it seems clear that the
home is no longer negligible as a source of contagion; and that
occupation may, perhaps, be one of the less important of the
factors which determine ‘the acquisition of infection with E
histolytica.

Geographical Distribution.—In the reports already published,
and in those now presented in Chapter III, there is some in-
formation about the present distribution of E. histolytica in
Britain. It is not complete, but it is, in some respects, suggestive.

Most of the persons in whom JF. histolytica has been found
have been interrogated regarding their usual place of resi-
dence: and this has been recorded. The workers at Liverpool,
Birmingham, Bristol, Brighton, Leeds, Sheffield, and Reading,
have found most of their infected cases among residents in the
districts in which they worked. The fact that not one of these
workers failed to find local cases of infection shows that E. histo-
lytica probably has a wide distribution. But by no means all
the cases examined were habitually resident in the places in
which their examination took place. Some of them had left
their native towns or villages—to undergo military training,

1 See p. 55, infra. 2 See p. 60.

47

and for other reasons—and were found, consequently, in places

to which they did not properly belong. For example, the Welsh

colliers examined by Matthews and Smith at Liverpool] did not

belong to this city: and it seems probable that they had con-

tracted their infections in their native country rather than in

Lancashire., Yet this is not absolutely certain, of course: and

this uncertainty must be borne in mind in attempting to draw

conclusions from the incomplete records which are available.
With the foregoing reservation, it may be stated that cases of

indigenous LH. histolytica infection have now been found in

England—north, south, east, west, and the midlands: and in

natives of Wales, Scotland, and Ireland. The records, from all

sources, contain instances of the occurrence of FE. histolytica in

persons usually resident in the following counties:

Lancashire

Yorkshire

Cumberland

Westmoreland

Cheshire

Shropshire

Staffordshire Carnarvon

Warwickshire Cardigan

Monmouth wan Carmarthen

Gloucestershire Glamorgan

Somerset

Berkshire

Hertfordshire

Northamptonshire

Sussex

London

ENGLAND 4

East Lothian _, § Derry
PaEND: Shetland Isles TRREAN | Cork

I have not thought it worth while to record the precise
localities; for the incomplete records at present available do not
supply sufficient evidence for attempting to estimate the geo-
graphical distribution of E. histolytica in detail. It is possible
that the parasite is commoner in some places than in others, but
there is no clear evidence of this in the records. The largest
numbers of cases have been found in the places where the longest
search has been made for them; and since no cases have yet
been looked for in many areas, a complete survey is out of the
question at the present moment.

Nevertheless, I believe that the available evidence indicates
clearly that E histolytica infection is prevalent throughout the
length and breadth of the British Isles. Probably no region—not
excepting even the smallest inhabited islands—will be found, if
investigated, to be free from infection. This conclusion harmo-
nizes with what is already known about the distribution of this
parasite in the rest of the world: for the evidence is steadily
accumulating to show that its occurrence is world-wide, and is
not limited to any particular region of the globe or race of
mankind.

Relation to Disease.—The workers at Liverpool ‘have, ap-
parently, found no evidence that the large number of healthy but

48

infected persons whom they studied were, as a class, more prone
to suffer from dysentery or other intestinal diseases than un-
infected persons from the same walks in life. The later workers
—whose results are here recorded—have obtained concordant
results. Histories of all the cases studied were obtained, as far
as possible, and recorded: and inspection of these records shows
that a past or present history of dysentery is apparently no
commoner in persons infected with E. histolytica tltan in those who
are nominally ‘uninfected’. The figures are, however, for various
reasons inconclusive. For example, when a person is found to
have suffered in the past from ‘dysentery’, it is now usually im-
possible to ascertain its cause. The complaint was generally
diagnosed on clinical grounds; and even if the patient is found
later to harbour E. histolytica it is by no means certain that this
parasite was the cause of the trouble. The patient may have
suffered from bacillary dysentery, whilst remaining a ‘healthy’
carrier of the amoeba; or he may have acquired his infection
after the attack of dysentery. A history of ‘diarrhoea’ is even
more difficult to interpret; for there are but few who, on being
closely interrogated, are found not to have suffered, upon occasion,
from this common complaint. Furthermore, when a person has
been examined but once, and found ‘negative’ for L. histolytica,
the conclusion that he is ‘not infected’ is by no means warranted.
Consequently, in all our series the ‘negative’ cases with a past
history of dysentery or diarrhoea cannot furnish us with reliable
statistics of the incidence of these diseases in persons uninfected
with E. histolytica.

The findings, given for what they are worth, appear to be as
follows for the infected persons so far studied. The Liverpool
workers, in their first published series, state of the ten cases of
E. histolytica infection investigated that ‘none of them gave
a history of dysentery’. The full histories of the cases in their
later series are not recorded, but it seems unlikely that these
cases were-—in this respect—substantially different from those in
the earlier series. Of the twenty-seven British carriers of E. his-
tolytica studied at Birmingham, Brighton, Bristol, Leeds, Sheffield,
and Reading, only one has a history of ‘dysentery’, while three
are stated to have suffered from more or less serious attacks of
‘diarrhoea’ in the past. It is easy to pick out random samples
of twenty-seven individuals from the ‘ uninfected’ persons in the
same series showing past records of diarrhoea or dysentery in
approximately the same proportion. It is noteworthy, moreover,
that there is not a single infected individual, in any series, with
a history of hepatic abscess.

(2) Entamoeba coli.—-It is now clear that E. coli, the large
harmless amoeba of the human bowel, occurs commonly through-

1 I exclude the case recorded by Armitage (1919) from the ‘British’ series; for
the patient, though he apparently contracted an amoebic abscess of the liver,
followed by another in the brain, in England, and had never been in tropical or
subtropical countries, was a native of New Zealand.

49

out the British Isles. This was to have been expected, and calls
for no particular comment. It occurs in both sexes, apparently
with equal frequency, and has been found in persons of all ages
from the second year onwards (Matthews and Smith, Miss
Nutt).

Although indigenous cases of E. coli infection were doubtless
known to workers in this country before the war, the first re-
corded in the literature appear to be two described by Smith and
Matthews (1917). Since then many others have been found by
the same workers and others. From the records it appears pro-
bable that the true incidence of infection with this organism in
the British Isles is high. Of the persons already examined,
probably between one-third and one-half were infected—taking
them in the aggregate. Some differences in distribution appear
in the various records, but for various reasons, already considered,
it is doubtful how far these are real. Campbell (p. 31) at
Bristol, and Miss Nutt (p. 33) at Leeds, found the organism
commoner in adults than in children: but at Sheffield Miss Nutt
(p. 85) found the incidence in the two classes approximately
equal. Matthews and Smith (1919, p. 364) give the following
figures —based on one examination per case—for three classes of
persons examined by them:

: Civilian Army
Children. Adults. Recruits.
Percent. infected with E. coli sag Lis _ 6.7 fae 18.2

In a group of 207 asylum patients they found no less than
45-9 per cent. infected—as a result of only one examination per
case. This indicates a very high rate of infection in this group.
(See Matthews and Smith (1919 a), p.91.) High figures were also.
obtained for Welsh miners and some other groups. To judge
from most of the larger series, and those in which more than one
examination per case was made—these series being freer from
errors due to small sampling and deficient examination—it
appears probable that 50 per cent. is a conservative estimate of
the true incidence of infection with Z. coli in the general popu-
lation of the British Isles. At present there is no conclusive
evidence indicating a localized distribution, except that derived
from lunatics in asylums—to which reference has just been
made.

(3) Endolimax nana.—This small non-pathogenic amoeba ap-
pears to be common in Britain. The first British cases of infection
were found by Matthews and Smith—reported by Yorke (1918)
—and by Miss’D. L. Mackinnon (1918). The latter found three
out of thirty-four soldiers, who ‘had never been out of England ’,
infected with this organism. Since then Matthews and Smith
and all the workers under the War Office Dysentery Committee
have found further infections in other classes of cases.

The percentages recorded in most series are low—the highest
being 12-1 per cent. found in asylum patients by Matthews and
Smith (1919 a). The patients were examined only once apiece:

50

and it may be noted that the inmates of another asylum, similarly
examined by Smith (1919) subsequently, gave a percentage of
only 8. Nothing else noteworthy regarding the incidence or
distribution of this amoeba appears in the records.

Although the figures so far obtained indicate that only some
9 to 18 per cent. of Britons harbour this organism, there is reason
to believe that this figure is too low. The organism is very small,
and infections are in consequence easily overlooked; and it was
not until comparatively late in the War that most protozoologists
in this country became familiar with it. Careful examination of
large numbers of soldiers returning from abroad has shown that
FE. nana is very common in them—being the next commonest
amoeba after E. coli. My own records show that it probably
occurs in not less than 50 per cent. of such cases.

(4) Iodamoeba biitschlii—So far as records are available, this
amoeba appears to be rare in Britain. It undoubtedly occurs,
however, though the findings indicate that it is present in less
than 1 per cent. of the population. The first indigenous infections
described appear to be those found by Matthews and Smith
(1919).1. Only one case of infection has as yet been recorded in
a child under twelve (Matthews and Smith), and at present the
records are too meagre for it to be possible to draw any con-
clusions regarding the incidence of the organism in relation to
sex, age, or occupation. I will merely note that this amoeba
appears to be less common in British residents than in troops re-
turning from overseas. The highest rate of infection hitherto
recorded in British cases is 1 per cent.—found by Smith (1919) in
a series of 504 inmates of a lunatic asylum.

The published records give figures for England and Wales
only. I may add, however, that Case 393 of Baylis (1919)—as
appears from his card entries, though not stated in his published
paper—was infected with J. biitschlii, and this shows that the
organism probably also occurs in Ireland. This is all that can be
said at present regarding its distribution in these islands.

(5) Dientamoeba fragilis.—Not a single instance of infection
with this small and apparently rare amoeba has been recorded in
any of the series here considered. That it occurs in persons who
have never left Britain is, however, certain: for I have recorded,
with Miss M. W. Jepps, one case of infection in a person belong-
ing to this category (see Jepps and Dobell, 1918). At present
this is the only British case known to me.

The organism may be commoner than these findings appear
to indicate, for it is small and extremely delicate, and perishes
soon after leaving the body. Its cysts are still unknown, and
the organism itself can only be found in soft stools examined in
a very fresh condition. Consequently, even when present it is

1 Recorded by these workers throughout under the name of ‘ Iodine cysts’, See
my book (1919) for the history of this organism.

51

probably often overlooked, and negative records cannot be re-
garded as reliable evidence of its absence.

(6) Giardia intestinalis.—This flagellate—better known under
the name of Lamblia—occurs commonly in people who have
never left Britain. The first British infections were recorded by
Smith and Matthews (1916), and since then it has been found by
every worker who has examined cases of this class—including
Miss Mackinnon (1918) and Baylis (1919), in addition to those
whose work is here reported.

The chief noteworthy fact about this protozoon is that it has
been found more frequently in children than in adults. The re-
corded figures are very striking, and may be briefly recapitulated
here:

Percent. G. intestinalis

~~.

Investigator. Place. Adults. Children.
Matthews and Smith! . Liverpool : ‘ 7.0 14.1
Campbell ‘ “ 7 Bristol . i 3.9 16:3
Miss Nutt ; ; Leeds. E é 3-8 39.8
5 : F 5 : Sheffield 7.2 15.8
McLean? . ; 3 Reading 9.3 17-4

The uniformity with which Giardia has been found more
frequently in children cannot be accidental, and it seems clear
that these figures must have a real significance. But what this
significance is, is not so clear. Matthews and Smith (1919) in-
terpret their findings as indicating that infection with Giardia
is actually commoner in children than in adults. They believe
that this protozoon—and others found in the human bowel—
‘may disappear from the intestine in the course of time’: ‘it
may be that the flagellate is mainly a parasite of children and
becomes rarer in older people’. This may be true: but it must
be remembered that failure to find a given organism in the stools
is by no means the same thing as absence of it from the intestine.
It is often extremely difficult to detect Giardia infections—in
adults, at all events—by examination of the faeces; and to find
an infection it may be necessary to prolong the examination until
the stools have been carefully searched on dozens of occasions.*
Figures which I have elsewhere published * appear to indicate
that the chances are about 7 to 2 against the infection being de-
tected by means of a single examination of the stools of the
average infected individual. Further, neither Matthews and
Smith, nor any other workers, have yet been able to adduce
a single concrete case in which a Giardia infection has been
proved to have died out. This organism is, in my experience,
remarkably persistent. I have had one infected individual under
observation for over ten years; aud although it is frequently im-
possible to find the organism in the stools, the infection is still

1 These figures (adults) are for 1,098 Army recruits.

2 Percentages calculated hy me from particulars entered on cards.

3 See my previous Report (1917), where this subject is considered at length.
4 Ibid. p. 18.

52

present, and has shown no signs of disappearing from the bowel.
The other common intestinal protozoa appear to be equally per-
sistent.

I therefore hesitate to accept this obvious explanation. I be-
lieve the figures merely show that Giardia is more easily found
in the stools of children than in those of adults: they do not
prove that children as a whole are more frequently infected. On
the other hand, it appears quite probable that children, indi-
vidually, when infected have heavier infections than adult
individuals. This would not be surprising, and many analogous
instances in which young animals show, individually, a far higher
degree of protozoal infection than adults of the same species
could easily be quoted. It seems not at all improbable that in
children, when recently infected, Giardia multiplies more rapidly,
and appears more copiously in the stools, than it does later in
adult individuals in whom the infection has become chronic. It
is perhaps easier, therefore, to find evidence of infection in
children ; but there is as yet no real evidence that children as
a class are more frequently infected than adults, and none that
Giardia infections tend to disappear when once established.

There is some very interesting evidence to show the age at
which Giardia infections may be acquired. Matthews and Smith
(1919) found no intestinal protozoa in infants during the first
year of life: but they found several infections with Giardia—and
also with other protozoa—in children aged between one and two
years, and concluded that they ‘may become infected with in-
testinal protozoa soon after they are twelve months old’. There
is conclusive evidence now, however, that Giardia infections at
least are contracted still earlier. .

Miss Nutt, at Leeds and Sheffield, examined the stools of
25 children aged 12 months or less: and she found Giardia in
no less than 6 of these. Her results—compiled from her cards—
were as follows:

Age of Child. No. infected with Giardia.
3 weeks . 3 ‘ c 1
3 months 1
9 4; 1
WW) 4, 1
12, 2

These findings are, 1 think, very remarkable. That a child
only 3 weeks old may already harbour Giardia would hardly
have been suspected. It implies gross contamination of its food
with human faeces: and since all the intestinal protozoa are
transmitted by similar means, it shows that—where suitably dirty
conditions obtain—a child may become infected with any in-
testinal protozoon shortly after birth.

(7) Chilomastix mesnili.—This flagellate appears to be fairly
common in Britain. It has been found by all the workers en-
gaged in the present investigation, but the incidence of infection
varies greatly in different records. Matthews and Smith (1919,

53

1919 a) tound 19 infections in all the cases (2,137, excluding
asylum patients) which they examined; a percentage of only
about 0-9. The other workers, whose reports are printed here,
found altogether 74 cases in 1,009 examined, or 7-3 per cent.
Even when allowance is made for the fact that the first series
was examined only once per case, and the second more frequently
in some instances, the discrepancy in these findings is consider-
able. Miss Mackinnon (1918) found 1 infection in 84 ‘ British’
cases at Southampton; and Baylis (1919) records only 0-25 per
cent, in his series of 400 naval cases. The highest figure re-
corded in any British series is 23-2 per cent., found by Matthews
and Smith (1919 a) in 207 patients in a lunatic asylum.

The figures generally—of which the foregoing are a sample—
show such variations that I am in much doubt as to their signi-
ficance. I have estimated roughly (p. 42) that the total
findings indicate that some 6 to 9 per cent. of the British popu-
lation may harbour this flagellate: but I am not disposed to
attach much importance to these figures. The only certain
conclusion that emerges from the findings generally is that
Chilomastia is apparently less common in British residents than
in soldiers who have seen service abroad. In such persons I have
invariably found a higher rate of infection.

The first British cases of infection with Chilomastix were re-
corded! by Yorke, Carter, Mackinnon, Matthews, and Smith
(1917). Nothing else regarding this organism seems worthy of
special comment here.

(8) Trichomonas hominis——Up to the present this flagellate
has been reported in one series of British cases only—the asylum
patients examined by Smith (1919) at Rainhill. He tound
altogether six infected out of a total of 504 examined. Of the
members of this series 34 had been abroad: but it appears that
at least one of the patients who had never left England (Case
J. Ho.) was infected with Trichomonas. Whether the other
infected cases were ‘ British’ or not is not stated.

In the other series examined by Smith and Matthews, and by
the later workers along similar lines, there is not a single case of
Trichomonas infection reported. None was found by any worker
tor the War Office Committee, and none by Baylis (1919) in his
naval cases, nor by Miss Mackinnon (1918) in her series of ‘ British ’
soldiers. It thus seems clear that the flagellate occurs in persons
who have never left Britain, though it is uncommon; and at
present there are no figures which permit of even an approximate
estimate of its frequency.

Trichomonas hominis can, as a rule, be found only in soft or
liquid stools, and its cysts are at present unknown. Consequently
it is not surprising that it has not been found in a large number
of healthy persons with normally formed stools. Its apparent
absence cannot, therefore, be taken to prove that it is as uncommon
as the findings might at first sight seem to indicate.

1 Recorded under the name Tetramitus.

54

(9) Other Protozoa.—No protozoa other than those just con-
sidered have yet been found in the stools of persons who have
never left the British Isles. Nevertheless, I think it worth while
to point out this obvious fact, as it may direct further attention
to the point and possibly induce some workers to bring forward
further records or undertake new investigations.

I would particularly emphasize the fact that no infections with
intestinal coccidia or with Balantidium appear to have been
reported in British residents who have never been abroad. As
regards the former, it may be noted that there is one British case
of supposed coccidiosis of the liver (Silcock, 1890); but this is
still somewhat doubtful. I have discussed this case elsewhere,
in a review of our knowledge of coccidiosis in man (1919 a), and
need say no more about it here. Since I wrote this paper, no
new facts have, to my knowledge, come to light.?

As regards Balantidiwm coli, I would point out that it is
somewhat singular that no British cases of infection with this
ciliate appear to have been recorded. It is now generally accepted
that B. coli is a parasite proper to the pig, from which animal man
may occasionally acquire an accidental infection. Swineherds and
others particularly associated with pigs are especially liable to
balantidiosis. In parts of the British Isles—e.g. in rural Ireland
—conditions conducive to infection are apparently not lacking:
and one would expect human cases of balantidiosis to occur, from
time to time, if the parasite were present in our native pigs.
From personal experience I can say confidently that it is. Ihave,
in fact, never examined the faeces of pigs in this country carefully
without finding Balantidium present, often in large numbers.
It seems, therefore, somewhat remarkable that no human cases of
balantidiosis are yet on record—so far as I can ascertain.

The other intestinal protozoa described from man are at present
too little known or too doubtful to merit special individual mention
here.

B. The Spread of Infections in Britain.

Although much information concerning the incidence of
protozoal infections in Britain has now been obtained, very little
direct evidence is yet available to show how such infections are
spread through the community. Such facts as have been elicited
may be briefly mentioned here.

All the intestinal protozoa of man—with the possible exceptions
of Trichomonas hominis and Dientamoeba, whose cysts are still
unknown—are probably transmitted from man to man in the same
manner. The active forms of all these organisms are capable of
living in the intestine, where they multiply by fission. Outside
the human body, however, they cannot long survive. They have

1 An English case of intestinal ‘coccidiosis’ has, however, been recently described
by Lockhart-Mummery and Gabriel (1919). Through the kindness of Dr. F. G.
Crookshank I was able to examine sections showing the structures interpreted as
coccidia, and I have no hesitation in saying that they were neither coccidia nor any
other protozoa ; and consequently that this case was certainly not one of coccidiosis.

55

but feeble powers of resistance, and are rapidly killed by drying
and all conditions which differ from those under which they
normally live in the bowel. If ingested in the active state by
a human being they always perish. In other words, the active
organisms can live in the intestine only, and are incapable of
playing any direct part in the spread of infections from one host.
to another. But in certain circumstances—which are not yet
properly understood—these active organisms can encyst in the
bowel and pass out in the form of more or less resistant cysts
with the faeces. It is by ingesting such cysts that a new host
becomes infected.

It is thus evident that the actual source of infection is,in every
case, the person who harbours active protozoa in his gut and
passes their cysts in his stools: whilst the spread of infection to
other persons is brought about by any or every circumstance which
insures these cysts being ingested, while still fresh and living,
by another individual.

It seems reasonable to assume that infections are usually
acquired by swallowing food or drink which has been recently
contaminated by fresh human faeces containing cysts. This
contamination may conceivably occur .in a variety of ways—by
the agency of flies, the pollution of water with sewage, or other-
wise. The present reports supply no direct evidence bearing on
these problems, and it is therefore unnecessary to discuss the
various possibilities here. What they do supply, however, is
evidence that the contamination of food and drink with fresh
human faeces—however it may occur—cannot be uncommon in
this country: and it furnishes some suggestive facts which may
indicate where the most important foci of infection: should be
sought. The evidence for the former conclusion is indirect, and
is derived from the demonstration that a considerable proportion
of the people of this country has actually acquired infection, in
some way, with intestinal protozoa: for the latter inference, the
evidence is contained in some observations of Matthews and Smith,
which will be briefly considered here.

These workers (Matthews and Smith (1919), p. 365) ‘in order

to obtain a closer insight into the actual process of spread of
these protozoal infections ... singled out certain cases, chiefly
those [children] infected with E. histolytica, and have examined
the whole family of which each one wasa member’. They state
that ‘in only one family’ out of seven examined, were they ‘able
to examine the parents as well as the children and the records
in this case (Family I) proved of great interest’. ‘In all the other
tamilies,’ they continue, ‘we examined-the children only. .
It is of great importance to keep clearly in mind that these are
the results of one examination only. They are therefore minimum
results. At least the infections recorded were present; probably,
in fact almost certainly, others also.’ Their results are recorded
in a table (op. cit., Table V, p. 366), which need not be copied here
in full. On account of its great interest, however, and as an
example of the results obtained, I give below—in a modified
form—the findings for Family I.

56

Protozoal Infections found in Family I.

Parents Children
——. pee.

Protozoa. IS. LS. LS. BS. Jas. J.S. M.S, D.S.
Entamoeba histolytica 3 + + + + + ee + +
E.coli. $ é . wee + + i + + + aii
Endolimax nana. e + + + + + ie + +
Giardia intestinalis . ists aie sae Hes vate aint + +
Chilomastix mesnili . ide Sas sith sd #34 + wes tiie

Ages. 41 41 16 18 11 9 7 3

[+ denotes that an infection was found, ... that it was not found during the single
examination made. ]

Matthews and Smith conclude, from all their observations,
‘that within certain families infections are much more common
than in the general population of children. This is strikingly
seen in Family I, where, in one family only, there are almost as
many £. histolytica infections as we have found in the 548 cases
taken from single members of different families. This applies
also to the other infections, particularly to &. coli and EH. nana.

These authors have remarked further that ‘there are at least
two possible ways in which this state of affairs may have been
brought about. (1) A single member (or some small number of
members) of the family has become infected in a way at present
unknown and from this source the infection has spread to other
members of the family... . (2) The whole family, or those mem-
bers of it who have similar infections, may have been infected
simultaneously, for instance by all eating food from the same
contaminated source, Matthews and Smith ‘think the former
method the more probable’: and with reference to the particular
families in question they add the following information. ‘With
regard to the possible source of these protozoal infections it may
be recorded that in each of the families investigated, one member
—1in six of the families the tather, in the seventh a brother—had
been abroad and had visited the home after going abroad. In five
cases this member of the family was a soldier and in two cases a
sailor. Itis therefore possible that all the infections had their
origin abroad. It is not at all necessary to make this supposition
however, for protozoal infections, as we have shown (Matthews
and Smith, 1919), are sufficiently common in all sections of the
population to warrant the belief that they may have existed in
this country before the way.’

Attempts were made to determine, by measurements of the
cysts, how many races of FE. histolytica and E. coli were present
in the members of two families. From the few observations
which they were able to make Matthews and Smith concluded
that ‘the evidence does not go far, but such as it is, it points to
one race, and therefore presumably one source of infection, for the
£. histolytica infection in the two members examined of Family II,
and to two sources ot infection in the four members of Family 1’.

There is but little that can profitably be added to the foregoing
observations atthe present moment. In this connexion, however,

57

I would call attention to the similar observations recently made
in Holland by Kuenen (1918)—considered more fully on p. 60;
and I would emphasize once more two of the important facts
which the present reports have revealed. These are, first, that
intestinal protozoa are far from uncommon in British children,
in whom they occur even in the first year of life. The statement
of Matthews and Smith (1919, p. 364 n.) that ‘liability to infection
does not appear to occur until the child has entered his second
year’ can no longer be regarded as a true proposition (see p. 52);
and the possibility of infection at a very early age will in future
always have to be considered in any discussion of the means by
which intestinal protozoa are disseminated. Secondly, we now
know that females are not less subject to infection than males;
and that domestic servants, cooks, and other female members of
the household may harbour E. histolytica and other protozoa.

We have seen also (p. 45) that the purveyors of food for
domestic consumption—such as butchers and bakers—are also
sometimes infected with # histolytica and other intestinal protozoa,
and they can certainly acquire such organisms without going
abroad. There is also some evidence that people who are closely
associated for considerable periods, and under conditions which
are not sanitarily perfect, are apparently apt to acquire infections
from one another. Atall events, the high rates of infection found
among colliers (see p. 45) and the inmates of lunatic asylums
(p. 46) appear to point in this direction.

It appears more than probable that all the common intestinal
protozoa of man occur indigenously in Britain; and with obvious
sources of contagion close at hand it thus appears no longer
necessary to seek a foreign origin for every case of protozoal
infection found in this country.

CHAPTER V. RECENT OBSERVATIONS ON THE OCCUR-
RENCE OF £. HISTOLYTICA IN FRANCE, HOLLAND,
AND GERMANY.

A pviscussion of the occurrence of E. histolytica and the other
intestinal protozoa of man in Europe generally, does not properly
come within the scope of the present Report. But since Britain
is a part of Europe, and since the British findings are of more
than local interest, it seems to me desirable to consider, before
I end, some comparable findings which have been recorded by
our nearest European neighbours. I shall therefore give here, as
briefly as possible, the recent results obtained, along similar lines,
by workers in France, Holland, and Germany—these being the
only adjacent countries from which, so far as I am aware, any
information is yet available.

No comprehensive survey of the intestinal protozoa harboured
by the native population appears to have been yet attempted in
any European country save Britain; and it has seemed to me

58

unnecessary to collect, at the present moment, all the scraps of
information previously published which appear to indicate that
most of the common intestinal protozoa of man are indigenous in
Europe generally. But the large number of native British infec-
tions with FE. histolytica revealed in the present Reports must be
considered in relation to the incidence of infection with this
parasite in the world at large—else we may form a very erroneous
opinion of its significance. The other intestinal protozoa found
in Britain should also, of course, be considered in a similar
manner: butas J. histolytica is, for practical reasons, more impor-
tant, and as information about the others is even more scanty,
I shall here leave them out of account.

The notes which follow are merely notes, and make no
pretensions to being an exhaustive survey of the literature.

The Occurrence of E. histolytica in France—There is now
evidence to prove that ZH. histolytica occurs indigenously in the
population ot France. The evidence is chiefly derived from
records of sporadic cases of amoebic dysentery and liver abscess
in persons who have never left France.

Galliard and Brumpt (1912) have published the results of
a careful study of an indigenous case of amoebic dysentery.
Their patient was a young male Parisian, aged 25, suffering
from acute dysentery and passing numerous amoebae in his
stools. The observations and experiments of these workers
show conclusively that the amoeba found was E. histolytica. In
a brief survey of the literature, the authors were able to find five
earlier recorded cases which, in their opinion, are to be interpreted
as indigenous French cases of disease due to E. histolytica (by
these authors called ‘ Amoeba dysenteriae’).

In the following year Paviot and Garin (1913) reported
another indigenous case of amoebic dysentery observed at Lyons.
The amoebae found in their patient—who died of the disease—
appear to have been undoubtedly £. histolytica. (I assume that
some of the authors’ observations were inexact.) These authors
also refer to a number of apparently similar previous cases.

A little later Landouzy and Debré (1914) described an indi-
genous fatal case of amoebic abscess of the liver, following
dysentery. The patient was a bargee who had never left France..
The clinical and post-mortem findings leave no doubt that this
also was a case of £. histolytica infection. In a useful table the
authors summarize previously published observations on 13
apparently similar indigenous cases of E. histolytica infection
recorded in France. They also add a warning of the danger
which may threaten the community as a result of the importation
of large bodies of colonial troops, infected with the parasite, into
France during the War.

Some interesting observations were recorded two years later
by Ravaut and Krolunitski (1916). They stated—but without
giving details—that since the outbreak of the War they had
found 25 cases of E histolytica infection ‘of indisputably indi-

59

genous origin’, (They call the parasites, however, ‘ Amoeba
Histolytica’ or ‘A. H.’) This large number of French cases was
discovered within the limits of only a ‘small area’ and ‘in the
space of several weeks’. These authors carried out an investiga-
tion of the stools of certain ‘individuals who did not show, at
the time of examination, any dysenteric symptoms’. They
examined, in all, 200 such persons, with the following results :

Of 72 orderlies in Hospital 8. (which had received many cases
of dysentery), 10 were found to be passing cysts of EF. histoly-
tica. Out of these 10 cases, only 4 had a previous history of
having suffered from intestinal ailments.

Of 82 orderlies in Hospital G. (in which dysentery cases had
been ‘ relatively very rare’), 2 showed cysts of E. histolytica
in their stools. Only 1 of these had a previous history of
dysentery.

Of 96 soldiers, who were in these two hospitals for various
ailments, 22 showed E: histolytica cysts. A dysenteric history
was elicited for 19 of these cases.

Among these 200 persons there were thus, in all, 34 individuals
infected with EL, histolytica. Of these, 24 had adysenteric history,
while 10 had apparently shown no symptoms due to their
infections—i.e. were ‘healthy’ contact carriers. From these
findings Ravaut and Krolunitski drew the conclusion: that as
many as 5 per cent. of healthy persons, in the region studied, are
infected with E. histolytica. Although this conclusion has been
copied—-and apparently accepted—by some reviewers of these
results, it is evident that the findings recorded do not warrant
such a deduction. They are of considerable interest; but
obviously they do not indicate what percentage of healthy
persons, with no history of dysentery, is infected with EZ histoly-
tica: and the authors’ comparison of these findings with the
results of Mathis—who found 8 per cent. of such persons infected
in Tonkin—is hardly possible. It should be added that the
histories of the individuals in these series are not recorded, so
that it is not possible to state how many—if any—of them can
be regarded as indigenous cases of EF. histolytica infection.

Labbé (1919) has recently recorded 8 cases of ‘amoebic
dysentery’ which he has observed in Paris. (The author refers
to the finding of ‘amoebae’ and ‘cysts’ in the stools, but does
not mention the species to which they belonged.) He states that
‘sometimes the disease might have been contracted during a
sojourn outside of France’, but ‘sometimes the amoebiasis was
contracted in France—even in Paris’. Though his cases may be
cases of amoebic dysentery which occurred in France, the par-
ticulars recorded do not show how many of the patients studied
had really acquired their infections in that country. (Only one
case is definitely stated never to have been abroad, and at least
two appear to have contracted their dysentery in the tropics.)

The Occurrence of E. histolytica in Holland.—About two years

60

ago some interesting observations were made and recorded in
Holland by Kuenen (1918). As practically no notice has hitherto
been taken of his work, I propose to summarize it here.

Kuenen, who appears to have been unaware of the observations
made in this country, is already known for his careful work on
amoebiasis in the Dutch East Indies. Having there studied the
intestinal protozoa of Europeans and natives, it occurred to him,
on his return to Holland, that similar investigations carried out
at home might yield interesting results. He therefore began to
study the stools of certain hospital patients in Amsterdam.
Before long he found some who were passing cysts of E. histolytica,
and although some of these carriers were found—as was to be
expected—to be persons who had been in the tropics and there
suffered from dysentery, he also, to his surprise, found several
cases of E, histolytica infection in Dutch residents who had never
been abroad. The following is a short summary of the indigenous
cases recorded.

Case 1.—A dock-worker. Though £. histolytica cysts were re-
peatedly found in his stools, he showed no symptoms referable to
his infection during his stay in hospital. He had never been
abroad, but had worked on board ships plying between Holland
and the Indies, and had therefore very probably been in contact
with colonial carriers of the parasite.

Case .2.—A military patient—a miner by calling. No in-
testinal symptoms could be elicited, and no history of association
with friends or relatives who had been in the Dutch Indies.
E. histolytica cysts were present in the stools.

Case 3.—A boy of 12, from Amsterdam. He had been suffer-
ing from dysentery, with intermissions and relapses, for 8 months.
Typical LE. histolytica amoebae were found in the bloody mucous
stools.

Case 4,—Another boy of 12, also from Amsterdam. Had
suffered from diarrhoea or dysentery, with intermissions, for
5 months. At different times he passed typical adult, precystic,
and encysted forms of E. histolytica in his stools.

The last two patients (Cases 3 and 4) had scarcely ever spent
a single day out of their native city. They were unrelated and
unacquainted with one another. The stools of all the other
members of their families were examined, but none of them
found infected with L. histolytica. The father of Case 3 had
spent 8 weeks in the Indies some 20 years previously; but apart
from this no indications of a possible colonial contamination
through other members of the two families could be discovered.
Both patients were treated with emetine hydrochloride hypo-
dermically, and were cured of their symptoms but remained
carriers of the parasite.

Case 5.—A married Amsterdam woman of 82. Since 18 years
old she had had attacks of diarrhoea, sometimes with blood and
mucus. Many cysts and precystic forms of E. histolytica were
found in her loose stools. No contact with relatives from the
Indies could be established. The husband and two daughters of

61

this patient were also examined. The husband was apparently
free: the children were, however, both infected (Cases 6 and 7).

- Case 6.—Daughter of preceding. She had occasionally suffered
from bowel trouble, and had passed some blood and slime in the
ee year. Typical EL. histolytica cysts were present in the
stools. a2

Case 7.—Daughter of Case 5. No symptoms of intestinal
trouble. A few &. histolytica cysts found in the stools.

Case 8.—A married woman, aged 32, a native of Wormerveer,
now living at Haarlem. Since the age of 18 she had suffered
from occasional severe attacks of diarrhoea. Large numbers of
E. histolytica cysts were found in her stools. The husband and
the son of this patient were also examined, but not found to be
infected. :

.. Kuenen discusses these cases at some length; but I will
merely note here that he concludes—in my opinion very pro-
perly-—that it is a mistake to regard E. histolytica as a parasite
peculiar to the tropics, and to seek an imported origin for all in-
fections discovered in Holland. LE. histolytica probably occurs
indigenously in that country; and if, as Kuenen believes, Case 5
contaminated her two children (Cases 6 and 7), infection can
evidently be spread there without foreign intervention.

. It may be added that Nolen (1918).was reminded, by Kuenen’s
paper, of a case which he studied in 1908. His patient was
a Dutch fisherman, aged 42, belonging to Vlaardingen, who had
suffered for 2 years from dysentery. In his bloody mucous stools
numerous active amoebae containing red blood corpuscles were
found. This was doubtless, therefore, a case of true amoebic
dysentery. Its interest lies in the circumstance that the patient
had never been, in the exercise of his calling, further afield than
England. He had never been in the tropics or in Eastern Europe,
and must therefore have contracted his infection either in Holland
or in England. ;

The Occurrence of KE. histolytica in Germany.—In a recent
paper Fischer (1920) has recorded several cases of indigenous
amoebic dysentery in Germany. This observer—who has had
experience of amoebic dysentery in China—appears to be un-
aware of the work already accomplished in England, France, and
Holland: and it is clear from his paper that he is not abreast of
the present state of knowledge of the amoebae of man. His
findings, in so far as they are of interest in this connexion, are
briefly as follows :

The author has examined the stools of 120 patients, suffering
from various complaints (mostly stomach and bowel affections)
in a hospital at Gottingen. He found &. histolytica in 2 (or 3?)
cases, and other intestinal protozoa in several others. The
positive cases were the following:

Case 1.—A young woman of 18, with clinical dysentery. In
the bloody mucous stools amoebae containing red blood corpuscles
were found, but no cysts. They were diagnosed as EH. histolytica.

62

It is stated that this is an ‘autochthonous’ case of amoebic
dysentery, but details of previous history are not given; it being
merely noted that ‘contact with amoebic dysentery patients
could not be established’. The administration of emetine appears
to have had no curative effect.

Case 2.—A ‘young’ man (no age stated) who had suffered
from clinical dysentery in the army. He had had frequent
stools—sometimes containing mucus, but no blood—accompanied
by tenesmus, for a year and a half. Amoebae (none containing
red blood corpuscles) and cysts measuring 10-12 » in diameter
were found in the stools, and identified as those of EF. histolytica.
No other essential facts are recorded.

Case 3.—Regarded by the author as doubtful. A man, aged
24, suffering from ‘colitis’, He had served in the army from
1914 to 1918. In his stools ‘a few amoebae with phagocytized
red blood corpuscles’ were found—also, it may be noted, macro-
phages containing the same inclusions. No cysts were found,
and no other essential details are given.

Although Fischer calls all these cases indigenous, and says
they prove that there are ‘ actually autochthonous cases of amoebic
dysentery in Germany’, no proof of these statements is supplied
in the present paper. The author merely records cases of
amoebic dysentery, or amgebic infection, detected in Germany.
Further evidence is necessary to establish the fact that the
infections were contracted in that country. The author does not
allude to any earlier observations bearing upon this subject, but
I may mention that at least one indigenous case appears to have
been previously recorded. For Jiirgens (1906) states that he per-
formed a post-mortem examination on a boy of 16, at the Charité
Hospital (Berlin), who had lived in Germany all his life but
presented, notwithstanding, typical lesions of amoebic dysentery.

The foregoing observations, while they show the necessity of
further work along similar lines, make it clear, I believe, that
E. histolytica occurs indigenously in France, Holland, and
Germany. They supply no exact figures for comparison with
those now available for Britain, but they indicate clearly that
the conditions found in this country are not peculiar. Indeed,
they make it highly probable that the incidence of infection with
E. histolytica—and other intestinal protozoa—within our shores
is not greater, nor the occurrence of amoebic diseases commoner,
than in the countries inhabited by our nearest neighbours in
Europe.

63

CHAPTER VI. CONCLUDING REMARKS.

Tue observations recorded in foregoing chapters have de-
monstrated conclusively that all the commoner intestinal protozoa
of man occur now in the population of the British Isles. The
species actually recorded, up to the present moment, are the
following :

1. Entamoeba histolytica.
2. Entamoeba coli.

. Endolimax nana.

. Lodamoeba biitschlit.

. Dientamoeba fragilis.
. Giardia intestinalis.

. Chilomastia mesnili.
8. Trichomonas hominis.

Raizopopa
(Amoebaea)

NIE OUP OO

MastTIGoPHORA
(Flagellata)

Infections with organisms belonging to the other main sub-
divisions of the Protozoa—the Sporozoa (e.g. Coccidia) and
Ciliophora (e.g. Balantidium)—have not yet been recorded.

The probable frequency with which the above protozoa occur
in Britain has been discussed in Chapter IV, and need not be
considered again here. I would only remark that the estimates at
which I have arrived are based upon the results of an examination
of the stools of over 3,000 British residents, of all ages and both
sexes, who had never left these islands. They therefore have
a substantial basis.

From a practical standpoint, the most important figures are
those relating to the incidence of infection with Entamoeba histo-
lytica—the ‘dysentery amoeba’. It has been demonstrated that
not less than 3-4 per cent. of the persons already examined
harbour this parasite; and it is probable that this figure—which
represents an absolute minimum—indicates that the true rate of
infection is of the order of 7 to 10 per cent.

The evidence now obtained appears to show clearly that
Ei. histolytica—as well as many other intestinal protozoa—occurs
indigenously in Britain. It has been suggested, however, that
the occurrence of large numbers of carriers of this parasite among
our home population at the present day is a consequence of the
War. There is, indeed, good evidence to prove that our troops
returning from the tropics, and other places where FE. histolytica
is known to be endemic, were often heavily infected ; and it is
true that an extensive infection of the resident civil population
of Britain has been demonstrated only since the outbreak of the
War. Consequently, the present state of affairs may be due to
the contamination of the civil population by an infected soldiery
returning home. This conclusion is, I believe, unjustifiable and
almost certainly incorrect. All the evidence is against it. We
know—from the early records considered in Chapter I]—that
long before the War £, histolytica occurred in British residents

64

who had never been abroad. We know that the parasite occurs
in widely separated parts of the country, and is comparatively
common. We know that it occurs at the present time in every
part of the world where it has been sought; and from its re-
lative harmlessness to human beings it seems probable that its
association with mankind is no new thing. The very fact that
E. histolytica is now comparatively common in persons who have
never left the country, whilst amoebic diseases are uncommon,
argues a degree of tolerance in the community such as is incon-
sistent with the supposition of its recent importation. Finally,
it has not been possible, in those gases where careful inquiries
have been made, to establish any direct connexion between the
native cases of infection and carriers returning from abroad.

The proof that E. histolytica and other intestinal protozoa
occur not uncommonly in the resident civil population of these
islands offers a wide and somewhat novel prospect for con-
templation by the British physician. The organisms themselves
are—save to those who have studied tropical medicine—
comparatively unfamiliar, and consequently apt to be regarded
with suspicion. Medical practitioners in this country will there-
fore desire some further information concerning the protozoa in
question, and will naturally ask what all the figures in this
Report really mean—whether they have any practical importance,
and, if so, what it is. To answer such questions finally is hardly
possible at the present moment. Nevertheless, approximate
answers can, I think, even now be found; and in the remainder
of this chapter I propose to give my own general conclusions
from the findings before us, and to discuss very briefly certain
problems and points of interest which they suggest.

In the first place, the figures mean—and to my mind this
is their worst meaning—that the inhabitants of Britain must
frequently consume food and drink which has been exposed to
gross contamination with fresh human faeces. The findings
demonstrate this conclusively. Of the protozoa here considered,
not one lives—so far as we know at present—anywhere but in
the human bowel. The cysts of all are discharged in human
faeces only; they cannot long survive outside the human body ;
and they cannot withstand drying. Infection can only be acquired,
in natural conditions, by swallowing fresh, undried cysts derived
from the faeces of a human being. Consequently, when we find
persons infected with intestinal protozoa we must conclude that
they have previously swallowed particles of the fairly fresh and
damp excrement of other persons; and when we find many people
presenting such evidence of pollution, we can only conclude that
the disposal of human faeces has not yet been brought generally
to that pitch of perfection which seems desirable.

The exact mechanism by which E. histolytica and other intestinal
protozoa are spread through the community is not yet fully under-
stood ; but from the facts now available it is clear that in the past
we have been too prone to lay stress upon foreign sources of
infection. We have ignored the fact that we ourselves harbour,

65

and have probably for centuries harboured, an abundance of
protozoa. If, at the present moment, a case of amoebic dysentery
were discovered in a British household, it is probable that an
attempt would be made to trace the origin of the infection to
some male member of the family who happened to have been
abroad—especially if he had served in the Army and there suffered
from ‘dysentery’. But it must, in future, be realized that the
source of infection is not necessarily the soldier son, returned
from foreign parts. It may equally well be the mother of the
family, who has never been abroad; it may be the nursemaid or
the cook—with no signs of dysentery about them; it may be the
greengrocer who handles the uncooked vegetables and fruit con-
sumed by the family. All these hitherto unsuspected persons
may be passing cysts of EH. histolytica and other protozoa by
thousands every day. Certain vocations, sojourn abroad, and
some other obvious factors are no doubt rightly regarded with
suspicion when considering possible sources of infection: but in
future suspicion will also fall upon the home circle, and the mere
circumstances that a man lives at home, does not work in the
sewers, has not had dysentery, and has never been abroad, can
hardly be regarded as sound reasons for believing that he is,
therefore, not infected with E£. histolytica,

The foregoing points are chiefly for the consideration of the
sanitarian, but there is another which is worthy of notice by the
statistician also, This is that the figures now obtained offer us
a méans of checking and correcting certain others which have
been previously arrived at. If a body of troops returning home
is subjected to protozoological examination, the results obtained
can now be more accurately interpreted than has been possible
hitherto. For example, if, in such troops, it is found that .some
10 per cent. are infected with £. histolytica, it is no longer easy
to argue that they have become contaminated abroad; or that
they are importing foreign parasites and thereby threatening
danger to the rest of the community. Such a figure would,
indeed, be almost devoid of significance, since we now have
evidence that the men concerned might have been already
infected to a similar extent before ever they set out from home.
The earlier records of the incidence of protozoal infections in our
returning troops will all have to be reinterpreted in the light of
the new observations.

The clinician will probably be more concerned with knowing
whether intestinal protozoa cause diseases, and if so, whether
these are sufficiently serious to be worthy of his attention.
Fortunately, our present knowledge, though imperfect, is able to
supply fairly satisfactory answers to these questions. It has now
been proved that two of the intestinal protozoa of man are faculta-
tively pathogenic—namely, Entamoeba histolytica and Balantidium
coli. The latter has not yet been found in man in Britain (i.e. as
an indigenous infection): the former has, however, been shown
to be fairly common in these islands; and as it can—in certain
circumstances—cause dysentery, liver abscess, and other diseases,

66

it obviously merits -very careful attention. There is as yet no
conclusive evidence to prove that any of the other intestinal
protozoa of man are pathogenic; while there is much evidence,
on the other hand, to show that they are, in the majority of
cases, harmless, As possible causes of human disease they may,
therefore, all be left out of account for the present.

As regards FE. histolytica, the evidence clearly shows that this
parasite is not responsible for any considerable proportion of the
disease of this country, though it shows equally clearly that it is
responsible for a small number of cases. This statement is, how-
ever, in all probability applicable to all other countries where the
parasite is known to occur. Britain is not in a peculiar position
in this respect.

The fact that the majority of indigenous infections with
E. histolytica have been found in comparatively healthy indi-
viduals, with no past or present symptoms of dysentery or liver
abscess, has led some people to wonder whether the ‘ E. histolytica’
of natives of Great Britain is, after all, the real E. histolytica of
the tropics—the amoeba which causes amoebic dysentery and
other diseases. There is, however, no longer any room for doubt
on this subject. It can be confidently asserted that the British
parasite is of the same species as the amoeba of tropical amoebic
dysentery. It is morphologically indistinguishable; and it is
similarly a facultatively pathogenic parasite—as the indigenous
human cases of amoebic dysentery and liver abscess indicate, and
as its transmission from healthy human carriers to the cat
confirms. In this animal the organism causes acute amoebic
dysentery indistinguishable from that produced by tropical
strains of the parasite.

Although there can be no doubt as to the identity of the
British parasite, there is possibly still room for wonder at the
fact that, although some 7 to 10 per cent. of the population is
infected, yet amoebic dysentery and liver abscess are rarities in
this country. But in contemplating this apparent discrepancy
the following points have been all too often overlooked. First,
infection with &. histolytica does not invariably, or even usually,
result in dysentery—even in the tropics or other places where
‘amoebiasis’ is reputed to be ‘endemic’. The belief that it does
was based upon faulty knowledge of the life-history of the parasite
and its relations to its host,! and it is now certain that it is the
exception, and not the rule, for E. histolytica to cause dysentery
or liver abscess in human beings. (This does not mean, of course,
that it does not usually cause ulceration or erosion of its host’s
intestine. It must always do this, as it is an obligatory tissue-
parasite: but the injury of the intestine is not usually sufficient
to give rise to any clinically recognizable symptoms.) The con-
ditions observed in England are thus not really peculiar. They
merely illustrate a special instance of a general phenomenon.

1 I need not labour the point here. The facts now are, or should be, well known.
The reader who seeks further information on the subject will find it in my book on
the amoebae of man (1919).

67

In the second place, it must be remembered that it has not yet
been proved that amoebic diseases are so excessively rare in
Britain as they are usually assumed to be. We know from the
observations of Dickinson, Moore, Saundby and Miller, Marshall,
and Worster-Drought and Rosewarne, that both amoebic dysentery
and liver abscess occur in persons who have never left this
country.1_ We can hardly doubt, from the more recent observa-
tions of Laidlaw (1918), that British cases of amoebic disease
will be found to be more frequent when they are more frequently
and carefully looked for. The work of Bartlett (1917), Laidlaw
(1918), and others, suggests that some at least of the cases hitherto
diagnosed as ‘ulcerative colitis’ by British physicians may be
really caused by E: histolytica. It is, indeed, almost impossible
to read such works as those of Gemmel (1898) or Hawkins (1909)
without suspecting that some of their patients suffered, though
they did not realize it, from amoebic dysentery. What other
conclusion can we°draw, for example, from Gemmel’s 80 autopsies
on cases of ‘idiopathic ulcerative colitis’—containing two dysen-
teric patients displaying ulcerated large intestines coupled with
abscesses in their livers? Furthermore, intestinal disturbances,
such as constipation and diarrhoea, are the commonest symptoms.
of infection with E. histolytica; and few practitioners will be
prepared to prove that among their patients suffering from these
everyday complaints there are none whose symptoms are due to
amoebic infection. Again, from the recent observations of Smith
(1919) it appears probable that some of the ‘asylum dysentery’ in
England may be amoebic ?— though from the work of Gettings and
others it seems probable that the proportion is inconsiderable.

It thus seems reasonable to conclude that amoebic diseases are
rare in Britain, as they probably are everywhere else in the
world—rare, that is to say, in proportion to the number of
persons infected with the parasite which ‘causes’ them—yet
not so extremely rare as defective observations and inadequate
statistics might lead one, at first sight, to suppose.

’ Thirdly, there is another point which should not be overlooked.
Although it now appears certain that ‘pathogenic’ and ‘non-
pathogenic’ strains of Z. histolytica do not exist *—all strains of
the species being tissue-parasites and consequently capable of
being ‘ pathogenic’ to a susceptible host—nevertheless it does
not follow that all strains are equally ‘harmless’ to all hosts.
Amoebic dysentery is the consequence of an incompatibility
between the amoebae and their host: it is an abnormal or
‘diseased’ condition for both. The carrier of the parasite is
a compatible host—one adapted to life with the amoebae, and
one to whom the amoebae themselves are adapted. Now it
appears probable that £. histolytica has parasitized man for
avery long time. This is indicated by its geographical distribu-

1 See Chapter IT.

? The observations of Gemmiel (1898)—alluded to above—also seem to point to the
same conclusion.

5 Cf. Dobell (1919), p. 58 et seq.

68

tion—apparently world-wide; by its frequency—a considerable
percentage of every race of man properly studied having been
found infected; and by the fact that its normal host is the
‘healthy’ carrier. In the course of ages E. histolytica has become
well adapted to man, and man well adapted to E. histolytica.
But there are many races of Man, and there are probably many
races of E. histolytica—some of these, indeed, being already easily
recognizable by the dimensions of their cysts. On analogy with
other protozoa it is probable that there are also many physio-
logically different races—at present indistinguishable. It is
therefore by no means an extravagant hypothesis to suppose that,
in the course of time, particular races of amoebae have become
specially adapted to particular races of human beings. The races
of E. histolytica occurring in Britain may well be peculiarly
suited to a life in Britons: the races in Africa to African natives.
But if the Briton goes to Africa, or if the African comes to
Britain, and acquires the parasite indigenous to the country,
it is possible that these new combinations might produce a
different result. It is possible that African strains of amoebae
may be unsuited to a life in British bowels, and may in this
abnormal environment give rise to dysentery more readily than
they do in theiy* native habitation in the negro. I will not
assert that this is the correct or complete explanation of what
appear at present to be the facts regarding the incidence of
amoebic diseases; but I think that some such hypothesis as the
foregoing offers the most plausible line of interpretation, and
I know.of no other which is consistent with all the established
facts—many of which are very curious and, at first sight, contra-
dictory.

I would emphasize here once more that the observations already
made in Britain, in France, in Holland, and in adjacent European
countries, all tend to show most clearly that E. histolytica is as
much at home in Western Europe as it is in the tropics. The
distribution of this amoeba is almost certainly world-wide. It
probably occurs now wherever there are men, and has so occurred
from timeimmemorial. £. histolytica,like the eagle of Prometheus,
preys upon the perpetually regenerated flesh of the human body;
and in the words quoted by ‘the beloved Physician ’, ‘ Where-
soever the body is, thither will the eagles be gathered together.’

In conclusion, I will sum up in a few words the present posi-
tion with regard to E. histolytica—as I conceive it—in so far as it
concerns the population and practitioners of this country.

Entamoeba histolytica is, or may be, a ‘cause’ of human
disease ; but usually it is comparatively harmless to the persons it
inhabits—at all events, in a population in which it has been long
established. The parasite occurs commonly in Britain, in the
resident native population, but to the majority of its hosts it
causes little or no inconvenience. It is probably not a new or
recently imported parasite, but at least as old an inhabitant of
these islands as the British nation. It has apparently caused but
little trouble in the past, and is not likely to cause more in the

69

future. Its prevalence, therefore, need not be regarded with
alarm. Nevertheless, the frequency with which it still occurs
indicates that conditions are still suitable for its dispersal; and
as these conditions imply personal uncleanliness or faulty sanita-
tion, it is clear that, as a nation, we still have much to learn
about individual and communal hygiene.

Moreover, though &. histolytica is often comparatively innocuous,
itis harmful and even dangerous to certain abnormally susceptible
individuals; and if such persons are rare, they are, nevertheless, not
negligible. Consequently, it will be necessary in future for British
physicians to remember £& histolytica when they are called upon to
treat cases of dysentery, chronic diarrhoea, ‘ulcerative colitis’, or
other intestinal ailments which may possibly be due to this
parasite; and to remember it also when they encounter patients
displaying symptoms of hepatitis, hepatic abscess, and similar
disorders, in the causation of which JH. histolytica plays a part.
Amoebic dysentery is a disease which, if promptly and properly
treated, is usually amenable to specific therapy; but one which,
when neglected or mistreated, often becomes chronic, leads to
much misery and unnecessary suffering, and frequently ter-
minates fatally.

Fortunately, modern methods of diagnosis have made it
possible to recognize the amoebic diseases with certainty ; and if
they have also revealed possibilities of trouble which have lain
hitherto unsuspected, they have at the same time put our know-
ledge of both the cause and the cure of these diseases on a sound
scientific foundation. Therefore, let the British physician grieve
not, nor be filled with forebodings at the outcome of the work
chronicled in these pages: but let him rather rejoice that it gives
him new light and new weapons—if he will but use them—for
his fight against disease and death.

REFERENCES.

Armitace, F. L. (1919). Amoebic abscess of the brain: with notes on a case follow-
ing amoebic abscess of the liver. Journ. Trop. Med. & Hyg., xxii, 69.

Bartietr, G. B. (1917). Pathology of dysentery in the Mediterranean Expedi-
tionary Force, 1915. Quart. Journ. Med., x, 185.

Bassett-Suiry, P. W. (1900). Abscess of the left lobe of the liver, with particular
reference to its amoebic causation. Brit. Med. Journ., ii, 552.

Bayuis, H. A. (1919). Incidence of Entamoeba histolytica and other intestinal pro-
tozoa among 400 healthy new entries to the Royal Navy. Lancet, i, 54.

—— (1920). Intestinal protozoa] infections, among officers and men of the Royal
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Carrer, H. F., Marruews, J. R., Mackinnon, D. L., and Smirn, A. Mains (1918).
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“Liverpool from various Expeditionary Forces.] Medical Research Committee,
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70

Dickinson, [W. H.] (1862). Large abscess of the liver consequent upon dysentery,
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—— (1881). Abscess of the liver consequent upon dysentery contracted in Eng-
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Dopett, C. (1916). Incidence and treatment of Entamoeba hislolytica infection at
Walton Hospital. Brit. Med. Journ., ii, 612.

—— (1917). Reports upon Investigations in the United Kingdom of Dysentery
Cases received from the Eastern Mediterranean. 1.—Amoebic Dysentery and
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—— (1919). The Amoebae living in Man: a zoological monograph. (London.)

—— (19194). A revision of the Coccidia parasitic in Man. Parasitol. xi, 147.

Doser, C., Gertines, H. S., Jerps, M. W., and Srepuxns, J. B. (1918). A study
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Medical Research Committee, Special Report Series, No. 15. (London.)

Dozett, C., and Juprs, M. W. (1918). A study of the diverse races of Entamoeba
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Doseit, C., and Srevenson, A. C. (1918). A note on the duration of infections
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Fiscuer, W. (1920). Ueber Darmamében und Amébenruhr in Deutschland.
Berlin, klin. Wochenschr., lvii, 7. ‘

GALLIARD, M., and Brumpt, E. (1912). Un eas de dysenterie amibienne auto-
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GemMeEL, J. F. (1898). Idiopathic ulcerative colitis (dysentery). (London.)

Haut, I. Warxer, Apam, D. C., and Savaez, R. E. (1916). Convalescent para-
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Hawkins, H. P. (1909). Anaddress on the natural history of ulcerative colitis and
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Jepps, M. W, and Dosetz, C. (1918). Dientamweba fragilis n. g., n.sp., a new in-
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Jeprs, M. W., and Meaxins, J: C. (1917). Detection and treatment with emetine
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JUreens (1906). Ueber Amében-Enteritis und ihre Beziehungen zur epidemi-
schen Ruhr. Berlin. klin. Wochenschr., xliii, 1607.

Kuewen, W. A. (1918). Amoebiasis in Nederland. Nederlandsch Tijdschr. v. G key
lxii, 1140.

Lasse, M. (1919). La fréquence des dysenteries amibiennes méconnues. Bull.
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Larwiaw, P. P. (1918). Cases of Entamoeba histolytica infection in British resi-
dents. Guy’s Hosp. Repts. (1917), lxix, 149.

Lanpovuzy, L., and Despre, R. (1914). Les ‘ Porteurs de germes’ importateurs de
maladies exotiques, particuli¢rement de la dysenterie amibienne. Bull. Acad.
Méd. Paris (8° sér.), Ixxi, 439.

Locxuart-Mummery, P. and GagrreL, W. B. (1919). Case of intestinal coccidiosis
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Low, G. C., and Dopetz, C. (1916). Three cases of Entamoeba histolytica infection
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Macxinnon, D. L, (1918). Notes on the intestinal protozoal infections of 1,680 men
examined at the University War Hospital, Southampton. JIbid., ii, 386.

Marsuatz, D. G. (1912). A case of amoebic dysentery occurring in a man who
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Marruews, J. R., and Smirn, A. Mains (1919). The spread and incidence of in-
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Liverpool Royal Infirmary. II.—Army recruits. III.—Children. Ann. Trop.
Med. & Parasitol., xii, 349. '

(1919), The spread and incidence of intestinal protozoal infections

in the population of Great Britain. IV.—Asylum patients. V.—University

and school cadets. JIbid., xiii, 91. 2

Moors, N. (1881). Abscess of liver in a child. Trans. Path. Soc. London, xxxii, 182.

Noxen (1918). Discussie [over Kuenen (1918)}. Nederlandsch Tijdschr. v. Geneesk.,
Ixii, 1145. F

Pavior, ae and Ganuy, C. (1913). Etude sur la dysenterie amibienne autochtone.
Journ, Physiol. et Path. Gén., xv, 342.

71

Ravaut, P., and Kroxunrrsxr, G. (1916). Les kystes amibiens. Importance de
leur recherche dans le diagnostic et la pathogénie de la dysenterie amibienne.
Presse Méd., xxiv, 289.

Saunpsy, R., and Mitumr, J. (1909). A case of amoebic dysentery with abscess of
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i, 771.

Surry, A. Mazins (1919). Cases of acute amoebic dysentery in asylum patients
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Surry, A. Mazins, and Marrnews, J. R. (1916). Lamblia infections in men who
have never been out of England. Brit. Med. Journ., ii, 389.

— — (1917). The intestinal protozoa of non-dysenteric cases. Ann. Trop.
Med. & Parasitol., x, 361.

—— —-— (1917a). Further records of the occurrence of intestinal protozoa in
non-dysenteric cases. Jbid., xi, 183.

Turnur, O. P., and Tayizr,} N. (1919). Preliminary report concerning the exami-
nation of 3,277 patients for the Entamoeba histolytica, &c. Journ. Roy. Army
Med. Corps, xxxiii, 245.

Watxer, E. L. (and Setrarps, A. W.] (1913). Experimental entamoebie dysentery.
Philippine Journ, Sci. (B., Trop. Med.), viii, 253.

Wenvyon, C. M. (1916). The protozoological findings in 556 cases of intestinal dis-
order from the Eastern Mediterranean War Area. Journ. Roy. Army Med. Corps,
xxvi, 445.

Wenvon, C. M., and O'Connor, F. W. (1917). Human Intestinal Protozoa in the Near
East. (London.)

Worsrer-Droveut, C., and Rosewarne, D. D. (1916). Amoebic dysentery in a man
who had never Jeft England. Brit. Med. Journ., i, 715.

Yorxr, W. (1918). The presence of Entamoeba histolytica and E. coli cysts in people
who have not been out of England. Trans. Soc. Trop. Med. & Hyg., xi, 291.

—— (1919). Amoebic dysentery in England. Brit. Med. Journ., i, 451.

Yorxr, W., Carter, H. F., Mackinnon, D. L., Matruews, J. R., and Smiru, A.
Maxis (1917). Persons who have never been out of Great Britain as carriers of
Entamoeba histolytica. Ann. Trop. Med. & Parasitol., xi, 87.

1 This name is misprinted as ‘ Taylor’ in the original.

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