NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
SCHISTOSOMA INDICUM, MONTGOMERY, IN EQUINES
7
tive results. Tonics containing strychnine were prescribed. The following post-
mortem findings were recorded:—
Liver enlarged, 32 lbs. in weight. Capsule covered with innumerable small
papules the size of a pea, giving an uneven surface to the liver. When the
liver substance was cut into, the surface had a marbled appearance. Some small
papules were found on the diaphragm and also on the serous coat of the small in-
testine. Four Habronema worms were found in mucous coat of the stomach. The
officer further stated that, about three weeks earlier, he had an identical case in a
mule which he destroyed for debility and that he had two more mules in the
hospital which he suspected to be suffering from the same condition. In the
histological report, it was stated that the picture was that of a very advanced
cirrhosis of long standing. Very little liver tissue could be detected in sections as
it had been replaced to a large extent by fibrous connective tissue. Naked eye
appearance was characteristic of " hobnail liver ". No parasites to account for the
lesion were detected and this result was explained on the hypothesis that in the
tissues received hitherto, including the present case, the lesion almost certainly
represented the end result of an infection, in which it was no longer possible to
discover the causal agent.
CASE REPORT NO. 6.
Pieces of lung and liver from mule No. 29 of No. 16 D. T. T. Company, Secun-
derabad, were received on 23rd August 1929.
The liver was studded with numerous millet seed sized calcified nodules both
on the surface and in the parenchyma. The small pieces of lung appeared a little
denser in consistence and contained what appeared to be fibrous nodules possibly
of old verminous origin. Bronchial and mediastinal glands were rather enlarged,
especially the latter, which was twice the normal size. The glands were œdematous
on section but showed no macroscopic lesions.
During life the mule had a pot-bellied appearance. There was very obvious
deficiency of muscle on the back and quarters and he showed markedly accelerated
respiration. The temperature was normal except on the first day of admission and
the animal fed well. He was admitted to hospital on 7th August 1929 with the
record of a progressive loss of condition and with the appearance of a case of
broken wind, but the character of the respiration was not typical of broken wind.
It was destroyed on 16th August 1929 as unlikely to recover.
Apart from the usual picture of nodulated portal cirrhosis of the liver, histolo-
gical examination of lung pieces made then revealed a chronic catarrhal type of
pneumonia, believed to be directly or indirectly connected with a parasitic infection.
8 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ III, I
CASE REPORT NO. 7.
Liver, lung, spleen and mesenteric gland, collected from mule No. 10, 2nd
Indian Divisional Signals, Quetta, were received on 28th November 1929.
Veterinary History Sheet.
Dark Brown Gold Mule No. 10.
Date of
admission.
17-5-24
22-6-25
30-5-27
15-11-27
27-9-29
Date of
discharge.
10-7-24
30-6-25
6-8-27
5-12-27
18-11-29
Number of
days.
54
8
68
20
52
Disease.
Debility
Ulcer, Bursati
....
Ulcer, Bursati
....
R. eye Pedal Ostitis O. F. .
Entozoa
Result.
Duty.
Duty.
Duty.
Duty.
..
For the last two years of its life, this mule had been in poor condition, no
muscles on back, pot-bellied, with obvious signs of ascites. During training that
year he proved to be of no use. Being unable to do his work he was admitted to the
Veterinary Hospital and treated for Entozoa, although no eggs or parasites were
found on fæcal examination. He was destroyed on 22nd November 1929 and
the post-mortem examination showed the following lesions :—
Serous flocculent fluid in the abdominal cavity. Liver cirrhotic, greatly
enlarged, weighing 31 lbs. and almost white in colour and permeated with hard
nodules. Lungs and spleen were in a similar condition. Blood from the portal
vein was examined but no schistosomes were found.
Histological examination showed the lungs and liver to be studded with very
numerous calcified nodules varying from the size of a pinhead to that of a pea.
Spleen also showed a few such nodules with areas of infarction, the last mentioned
lesion being probably connected with embolism from the same cause as of the
lungs and liver lesions.
CASE REPORT NO. 8.
Liver, lung, small colon and mesenteric lymph gland were received from
Military Hospital, Jubbulpore, on 7th March 1932.
The subject was a Bay Australian Mare—12 years old. Joined " G " Divi-
sional Signals on 8th August 1926 and was stationed at Jubbulpore and Secundera¬
SCHISTOSOMA INDICUM, MONTGOMERY, IN EQUINES
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bad. This horse had apparently been in good health until August 1931, the only
diseases of importance previous to this were colic in 1926, and influenza in
February-March 1931. She was treated for intestinal parasites in August-
September and for colic twice during September and October 1931. Admitted to
hospital on 5th January 1932 in poor condition and treated for intestinal para-
sites. As there was no improvement in condition, the animal was tested with
Mallein and afterwards with Tuberculin, in each case with a negative result. She
was destroyed on 27th February 1932. Post-mortem examination showed the
following:—
Liver.—Cirrhosis and small calcified nodules throughout the parenchyma, weight
47 lbs.
Lungs.—Numerous calcified nodules throughout, about the size of a grain of
gram.
Small Colon.—The external surface of the whole of this part of the intestine
was entirely covered with nodules of a fibrous consistency.
Large Colon.—Lesions similar to those of small colon were present throughout,
but were much less numerous.
Kidneys.—Oedematous, cirrhotic, capsules adherent. Mesenteric lymphatic
gland—small calcified nodules present.
Bladder.—One nodule on internal surface.
All other organs apparently normal, parietal pleura and peritoneum healthy.
Histological examination of serial sections revealed Schistosoma indicum ova in
the centre of the nodules in the liver, small colon, mesenteric gland and the lung.
Although considerable pains have been taken in compiling the above case
reports to include as comprehensive a description as possible of the symptomatology
of the condition on the basis of the covering letters which accompanied the samples
of specimens in the collection of this Institute, and which have now been proved to
be definite cases of Schistosomiasis, it will be readily realised that the clinical
descriptions given above refer to the late stages only. At this stage the animals,
from which the tissues were collected, had either naturally succumbed to the
disease or they were in such a " worn out " and incurable condition that they had
to be destroyed. Further in these advanced cases the symptoms exhibited were
obviously the result of the primary infection with its secondary sequelae. In
order that field workers may be in a position to recognise with precision the
clinical symptoms of the initial stages of this disease, it seems advisable that a few
remarks to supplement the case reports be made here. As a result of the present
studies and from what knowledge is available of such forms of human bilharziosis
10 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ III, I
as simulate the cases now under consideration, viz., Schistosomiasis of the Far
East (Katayama disease, due to S. japonicum) and Egyptian Schistosomiasis, due
to S. mansoni, it is easy to understand why the earlier symptoms of the equine
disease have failed to be recorded. The cercarial infection may take place in one
of two ways, viz., either through the cutaneous route or through the digestive
tract, and the latter seems more probable. The early stages of the disease may be
characterised by lesions involving the integument of the limb or the gastro-intes-
tinal tract. Whichever it is, there is little that is significant in an urticarial rash,
a papular lesion or a transitory gastro-intestinal catarrh to suggest the possibility
of a schistosome infection having been contracted. Occasional loose fæces asso-
ciated with some inappetence can be interpreted as mere indigestion, and premoni-
tory symptoms such as an intermittent high temperature are likely to be dismissed
with a palliative or symptomatic treatment. The occurrence of such minor ail-
ments will scarcely be recalled at the time when the disease has made good
headway, and when the affected animals (of which generally there are several)
begin to show signs of lethargy and unthriftiness for no apparent reason,
examination of fæces or of stomach contents collected by lavage is usually
carried out. Nematode worms or their ova in varying numbers may be detected
and anthelminthic or vermifuge measures adopted accordingly. Although some
transitory benefits may be seen, it is soon realised that the progress of
unthriftiness has not been checked. Icterus and anaemia develop gradually but
the suspicion of biliary fever is not confirmed by blood smear examination.
Chronic insidious conditions like subacute glanders or tuberculosis are also ex-
cluded as a result of tests with appropriate biological reagents. A vigorous tonic
treatment and liberal allowance of nutritious rations are prescribed but the animal
is found to be getting worse in spite of all human efforts to the contrary. Vary-
ing amounts of dropsical transudation common to conditions of debility may
accumulate in the dependent parts and this explains the entry of attacks of
lymphangitis or swollen legs made in the Veterinary History sheets of some of
these cases. Exudation of fluid into the peritoneal cavity also takes place
but in the normally obese abdomen this escapes notice. Part of it undergoes
reabsorption but increased exudation continues and with the progressive enlarge-
ment of the liver abdomen becomes pendulous. This appearance becomes more
pronounced because of advancing general emaciation. The enlarged liver may be
palpated per rectum and found to occupy considerable portions of the abdominal
cavity. On manipulation the animal may evince pain. The back muscles are
greatly atrophied and when the liver has undergone enormous enlargement, the
patient has the appearance of a gravid mare, to employ the expression used by
Williams [1914]. With the extension of the malady, circumscribed multiple foci of
SCHISTOSOMA INDICUM, MONTGOMERY, IN EQUINES
11
the disease affect various internal organs, e.g., intestine, liver, lung, spleen, pancreas,
etc. The pressure exerted by the enlarged liver and the reduced functional acti-
vity of the affected organs lead to metabolic disturbances; interfering with the
absorption and digestion of food respiration and circulation. A cough of varying
intensity and recurring attacks of diarrhœa are to be expected.
In connection with the above attempt to describe the probable course of a
typical case of this disease, it will be of interest to study some actual photographs
(Figs. 613 and 614) of a Chinese boy suffering from chronic Schistosomiasis of
the Far East, as given by Byam and Archibald [1923] in their notable treatise on the
" Practice of Medicine in the Tropics ". It will be noted that the boy has under-
gone an extreme form of emaciation and weakness, the abdomen shows an upper
distension and the feet are dropsical.
With regard to the geographical distribution of the condition, it appears to be
mainly restricted to the northern parts of India, though specimens have been
received from places as far south as Secunderabad and as far east as Muzaffarpur
in Bihar. Each of the different species of the equine tribe appears to be equally
affected and it is generally the older animals, which suffer most.
MORBID ANATOMY.
Liver.—The changes in this organ should be considered first, since this is the
seat of the most easily recognisable gross changes, but before taking up a consider-
ation of the hepatic changes peculiar to this disease, it is desirable to refer to
certain peculiarities of the equine liver. The horse is not provided with a gall
bladder and hence it is rarely the subject of any biliary concretions. Infection
with flukes is not common and it is only rarely that cancerous growths are
encountered in this organ of the horse. Yet the size, weight, colour and consis-
tency of the organ vary in quite a number of cases for no apparent cause. To
quote McFadyean [1889], the horse appears to be more frequently the subject of
hepatic cirrhosis than any of the other domesticated animals. In the disease to
be described here, the surface of the organ is comparatively smooth in the greater
part of its extent, and pale whitish patches or strings of fibrous tissue may be seen
on the capsule as an evidence of appreciable perihepatitis possibly supervening on
ascites or peritonitis. The organ is invariably enlarged and is much heavier than
normal. The weight ranges from 15 lbs. to 90 lbs., the latter figure being recorded
by Williams [1914]. The heaviest liver from which portions have been forwarded
to this Institute was stated to be 75 lbs. Generally the shape of the lobes is
maintained though one lobe may be a little more enlarged than the other and at no
stage has any atrophy of the liver been noticed, contrary to what is known to occur
in " hobnail" liver.
12 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ III, I
Numerous minute greyish white or chalky white nodules resembling miliary
tubercles can be seen immediately beneath the transparent capsule (Plate I,
specimen Nos. 1532 and 562 iii). These nodules are more or less calcified, as large
as a sago grain, but rarely, they may attain the size of a split pea. Palpation of
the surface gives a slightly irregular feel, but the organ is never characteristically
' hobnailed ' even in an extreme case. Occasionally several advanced nodules may
be seen crowded together over the surface of the organ (Plate I, specimen
No. 750-B). In rare cases elevated nodular areas of induration may also be seen
protruding in a like manner (Plate I, specimen No. 993). Degenerative
softening of the nodules has never been seen to be associated with the condition.
The organ cuts with a gritty or cartilaginous feel, and then will be seen many more
minute nodules which are red in the early stages but vary from greyish or greyish
white to pearl white in colour as the disease advances (Plate I, specimen
No. 1558 left). If an individual nodule is removed with the point of a knife and
a caustic potash preparation of the crushed material be examined under the
microscope one or two oval, spined eggs may be seen. The cut surfaces present
a coarse net-work of grey or greyish white bands of fibrous tissue of varying breadth,
enclosing in each mesh rounded islets of yellow or yellowish brown hepatic tissue.
When the disease has advanced further, the linear tracts of connective tissue become
so thickened and prominent as to present a marbled appearance or a " claypipe
stem " picture due to thickened bile ducts as delineated by Symmers [1903] in cases
of Egyptian Schistosomiasis (caused by S. mansoni). The liver may be so densely
packed with the nodules in varying stages of calcification and organisation that
very little true liver tissue can be recognised by the naked eye. The old nodules
may be so highly calcified that they readily become enucleated on the slightest dis-
turbance with the knife (Plate II, Fig. 1).
The development of the lesion in this equine affection takes place in the same
manner as in the case of other forms of schistosomiasis. There are certain
differences, of course, but they may be ascribed to the different degrees of patho-
genicity of the species of the parasite concerned and probably also due to the
varying powers of resistance possessed by the invaded equine tissues. The essential
lesion of the disease is a nodulated cirrhosis, practically restricted to the portal
tract in the initial stage (Plate III, Fig. 4). The nodule in its earliest stage
is mainly cellular in character, being composed of a heavy accumulation of mono-
nuclear neutrophile cells and rare polymorphonuclears which again are loosely
surrounded by a few delicate fibrils of connective tissue (Plate III, Fig. 2).
With regard to the origin of these fibrils careful examination of sections has shown
that they are merely the normal supporting tissue which has become arranged
around the irritant in order that it may be phagocytised in situ. The offending
PLATE III.
FIG. 1. (×68)
FIG. 2. (×480)
FIG. 3. (×100)
FIG. 4. (× 14)
For explanation see page 27.
PLATE IV.
FIG. 1. (× 55)
FIG. 2. (× 330)
FIG. 3. (× 240)
FIG. 4. (× 55)
For explanation see page 27.
SCHISTOSOMA INDICUM, MONTGOMERY, IN EQUINES
13
ovum lies quite free in the centre and it may be mentioned here that during these
studies sections of the female worm also have been seen in the centre of these
nodules in one sample of tissue only (Plate IV, Fig. 4). With the infiltration
of eosinophile leucocytes becoming denser in the surrounding areas, the formation
of rings of younger connective tissue takes place from the periphery inwards, the
earlier formed strands having attained maturity in the meantime. As the nodule
proceeds to further development, the ovum may still continue to lie freely in a
central cavity of the nodule or a kind of fibrinous, eosinophile, degeneration
' lymph' may accumulate around it. In the latter case, a varying number of
wandering cells with pyknotic and fragmented nuclear material is recognisable in
this pale reddish mass (Plate III, Fig. 3). The amount of the degenerated
cellular debris lying in the eosinophile substance may be considerable depending
upon the extent of toxic material elaborated by the developing embryo from inside
the egg-shell and this amorphous substance generally forms an irregular area
around the ovum. Some eosinophile leucocytes may reach this area of degenerated
material and a few others are seen lying in between the circular rings of more or
less developed fibrous connective tissue, but the densest eosinophile concentration
continues to be in the immediate proximity of the fibrous capsule of an individual
nodule, but always outside the latter (Plate III, Fig. 2). Phagocytic activity
around the central amorphous mass manifests itself and fibrin-like threads are seen
radiating out in a loose manner. The phagocytic cells are then seen to assume
a radial arrangement, with the broader parts of the cells directed outside (Plate
IV, Fig. 3). In some nodules the. arrangement may be so well developed as to
suggest a relationship with the classical " ray fungus ". In the opinion of Shafi
Mohammad [1931] these radiating and nucleated filaments are giant cells which
have been flattened out and elongated due to the pressure and counterpressure
exerted by the formation of concentric rings of fibrous tissue and this view is in
conformity with the findings recorded here. With further organisation, the radial
arrangement of elongated cells is lost and more or less successful attempts at giant
cell formation become manifest. Commencement of calcification begins immediately
around the ovum, the cellular contents of which seem to have lost the character
of viability, the egg-shell having undergone a partial crenation and blackening.
Lime salts have been seen to be deposited in the concentric rings of connective
tissue (Plate IV, Fig. 1). [It may be parenthetically mentioned here that the
same degree of predisposition to calcareous degeneration of the liver has not been
observed in similar bilharzial conditions which occur among human beings in Egypt
and the Far East]. The deposition of lime salt progresses with further organisa-
tion, fibrosis and giant cell activity (Plate IV, Fig. 2) until in the completely
fibrosed nodule, nothing excepting a part of the disrupted egg-shell can be seen
SCHISTOSOMA INDICUM, MONTGOMERY, IN EQUINES
15
cells generally remain healthy for an extremely long period. It has been seen earlier
that the liver undergoes a very pronounced hypertrophy in size but in the strict
sense, the term hypertrophic cirrhosis would scarcely apply to this condition since
an actual hypertrophic increase of liver cells has not been detected in these studies.
In seeking to find an explanation for the presence of the most advanced and the
earliest lesions side by side in the same liver, one is inclined to the view that the
ova have been carried to the liver at different times from larger veins supplying
other viscera, in particular the intestines. The obliteration and occlusion of the
majority of the portal vessels, the extent of which can be appreciated from Plate
II, Fig. I, would scarcely afford sufficient room for a migratory gravid female
to lay eggs in situ and then to escape.
As regards the ovum which is found in these lesions, it is a typical Schistosome
ovum, with a terminal spine, and as will be seen later it agrees in size with the
limits laid down for the ova of S. indicum, Montgomery. The egg-shell is composed
of a peculiar chitinous material, which is highly resistant to the phagocytic action
of body cells but the developing miracidium is readily destroyed by the phagocytes,
which appear to have no difficulty in obtaining entrance into the shell-cavity.
Although the egg-shell is soft enough to lose its characteristic shape or contour, the
persistence of disrupted remnants with a betraying spine in the centre of an altogether
fibrosed nodule, is a very striking and common occurrence (Plate IV, Fig. 1).
Another remarkable finding has been the persistence of a couple of eggs side by side
in a centre of dense calcification, there being no change in the shape of the eggshells,
contrary to the usual crenation or disruption that is generally met with. Of the
dozen or more ova that have been measured from sections of the liver, the largest
was found to have 0.128 × 0.040 mm. as the dimensions, whereas the length of a
number of eggs varied from 0.084 to 0.094 mm. and the width from 0.031 to
0.041 mm. The eggs seen in sections of intestine were of similar sizes but a few
small eggs, having dimensions like 0.031× 0.012 mm. or 0.069×.021 mm. have
been seen. The small sizes probably refer to the angle at which they were cut.
An egg in a lung section measured 0.85× 0.033 mm. and one from the mesenteric
gland was .079 × 027 mm. The length of the ova of S. indicum measured by
Montgomery varied from 0.092 to 0.10 mm., the width from 0.042 to 0.044 mm.
Intestines.—Although these bilharzial lesions are generally restricted to the
large intestine, they may encroach upon the small intestine and in rare advanced
cases, even upon the stomach. The appearance of the lesions involving either the
mucous or the peritoneal surface is practically the same in the different parts of the
digestive tract but in the majority of cases both surfaces are equally affected. In
fact, if one examines carefully the thickness of the gut wall, no layer is found to be
B
PLATE V.
FIG. 1. (× 45)
FIG. 2. (× 57)
FIG.3. (× 27)
FIG. 4. (× 21)
For explanation see page 27.