NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
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THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY. [V, III
The indirect method of the histologist and pathologist may, however, teach
us a great deal. The papers summarised by Hoeppli (1927) on the methods by
which parasitic nematodes may feed, and the work of Fourie (1931), Mueller
(1929) and others, demonstrate this. These papers give us information about
the histological effects of nematodes on the tissues of their hosts, and also some
information about the effects of the parasitic larvae. Hoepplis' summary, and
his own work also show that adult nematodes, whatever their parasitic larvae
may do, probably feed, as general biology would teach us to expect, in different
ways according to the nature of their mouths, and that degrees of parasitism can
be discerned among them, similar to those shown by other parasites and indicated
by similar structural differences.
Some nematodes, such as the hookworms, have buccal teeth with which
they browse upon the epithelium of the alimentary canal. The work done upon
these species strongly suggests that they do, in fact, digest the tissue which they
thus rasp or suck off. It has been suggested that they also help, by the damage
they thus do, the entry of pathogenic organisms into the submucosa and the
blood.
Taylor and Purchase (1931) could not, however, experimentally prove that
the entry of pathogenic organisms is thus facilitated by damage done to the
alimentary canal. Their method was to introduce into the alimentary canal
pathogenic organisms together with, but necessarily outside, the infective larvae.
The writer (1933) found that B. coli, and presumably pathogenic organisms as
well, could be bottled up, so to speak, inside the intestines of the first parasitic
larvae, so that theoretically they could be inoculated by these into the submucosa
of the host, into which they would burrow, each larva acting like a hypodermic
needle. It is possible, therefore, although attempts to infect animals in this way
have so far failed, that nematode larvae may thus transmit disease whether they
damage the gut extensively or not. There is here an interesting field for investi-
gation which would throw much needed light, not only on the food of both the
larvae and the adult worms, but also on the transmission of bacterial diseases
by nematodes.
*
*
*
*
Another interesting problem is opened up by the demonstration by Hoeppli
(1927) and others that nematodes embedded in the walls of the alimentary canal
may be surrounded by areas of cytolysed tissue upon which may they be feeding.
It is supposed that the substances producing this sytolysis are specific enzymes
produced by the nematodes to prepare the tissues for digestion; and Mueller
(1929) suggests that it is the particular function of the so-called excretory system
of nematodes to produce these substances. This system certainly shows little
morphological resemblance to any of the excretory organs of other animals.
BEARING OF PHYSIOLOGY OF PARASITIC NEMATODES ON THEIR CONTROL.
281
There is here, therefore, an interesting problem requiring the co-operation of the
morbid anatomist, the physiologist and the pathologist. It is typical of a great
many problems of the same type that urgently need investigation, because the
study of them may help us to treat the specific damage caused by nematodes.
Among other problems of this kind are the possible effects of nematodes
upon the calcium metabolism of the host, either through indirect effects on the
parathyroids or in some other way, and also their effects upon the general meta-
bolism of the host. Stewart and Shearer (1933) are investigating these. Much
work has also been done upon the effect of vitamins in the diet of animals infected
with nematodes. It seems that lack of vitamins increases the liability to in-
fection, but this may be only part of the well-known increased susceptibility to
disease due to the same cause, because it has been concluded that nematodes
do not themselves feed upon the vitamins. The writer found that the addition
of vitamins to hanging drops containing first parasitic larvae had no effect upon
their development.
The effects of the larval stages upon the host, whether these migrate through
the tissues or not, need much more investigation. More detailed physiological
study is also needed of the larvae of such wholly parasitic species as Trichinella,
their " encystment" in the muscles, and the general question why such larvae
come to rest in certain situations. It is possible, for example, that their meta-
bolism is in some way associated with glycogen deposits, so that the muscles and
the liver are particularly favourable to them. Whether a special mode of respira-
tion determines such an association is unknown, although there is some evidence
that the respiration of nematodes may be similar to that of muscle tissues (Slater,
1928). A similar tendency of cestode larval stages to congregate in certain
tissues may have a similar explanation.
*
*
*
*
Mueller's work (1929) upon the nematode cuticle opens up the general question
of excretion by nematode parasites. He found that the cuticle of a freshly killed
adult Ascaris was readily permeable, under the conditions of his experiment,
to urea and potassium iodide, but that it would not allow, under the conditions of
his experiment, glucose to pass through it, unless a 5 per cent. solution of this in
saline was used and even then only small quantities came through. These experi-
ments need verification and repetition under different conditions—at a constant
body temperature, for example. Other experiments should be done, not with
dead nematodes removed from the body of their hosts, but with living nematodes
or their larvae, in artificial media more closely resembling the body fluids, if not
in these themselves. The first parasitic larvae could be exsheathed artificially
and thus studied in sterile media by the writer's (1933A) method. They could,
however, only be so studied by those who are competent to study the biophysics
K
BEARING OF PHYSIOLOGY OF PARASITIC NEMATODES ON THEIR CONTROL.
283
such worm-free animals, and could meet the cost and labour of maintaining them,
we should probably only succeed in producing races of domesticated animals which
would be more, instead of less, susceptible to diseases due to parasites, a procedure
which is exemplified to-day by the various breeds of dogs and other inbred animals
fostered by civilisation, if modern man himself, indeed, is not the most striking
example of it. For this reason also we shall be wiser to study the plan adopted by
nature herself, and to seek to produce animals healthy because they are in equili-
brium with their parasites.
Among the conditions upon which this equilibrium depends, are the factors
governing the so-called resistance and immunity to nematode and other metazoa
parasites. Taylor's (1934) recent field experiments relating to this intricate
and difficult question, are valuable. We do not know yet whether this so-called
immunity and resistance resembles that known to bacteriologists or not. Some
of the work summarised by Taliaferro (1929) and also the work done upon specific
toxins produced by some nematodes and the antitoxins to these manufactured by
the hosts, suggest that it is. The recent work of Stumberg (1933) on the detection
of the proteins of Haemonchus in the sera of infected sheep and goats seems parti-
cularly promising. Valuable methods of diagnosis of nematode infections, as well
as of treatment of them, may emerge from work of this kind. It seems important
especially, that we should not allow the immunology of bacterial infections to
influence unduly our study of any similar phenomena which the investigation of
diseases due to metazoa may bring to light. Much recent work suggests indeed
that we are as yet only on the threshold of a field of research the future results of
which may alter many of our conceptions of diseases due to metazoa. It may show
us, among other things that what is now called an age-resistance to nematode
infections is in reality traceable to definite physiological relationships between
host and parasite, and that inbreeding, too much coddling and care of domesti-
cated animals and other farm practices which tend to weaken resistance to
disease that has been acquired in the evolution of the species concerned, may all
be doing more harm than good, and that there is a limit to the modern tendency
towards elaborate supervision and care of farm stock, beyond which disaster and
and not improvement lies.
There is, moreover, another reason why we shall do well to study the physio-
logical relationship of the host and its parasites, and try to base remedial measures
upon these. It will always be cheaper and easier to apply such measures, because
they will be readily combined with normal farm practice. They would also relieve
us of the dangers inseparable from the use of some of our most efficient
drugs. They would relieve us, for example, from the use of carbon tetrachloride
which, efficient though it is, may have effects on the host, even when it is used
by experienced workers, which are worse than those of the disease which it is
designedto cure.
K 2
BEARING OF PHYSIOLOGY OF PARASITIC NEMATODES ON THEIR CONTROL.
285
exerted. Our object, it should be remembered, is not necessarily to kill all the
nematodes present, but to inhibit their activities and propagation, without at
the same time injuring their hosts.
This mehod of treatment by giving one drug with the object of rendering
the parasite more susceptible to another drug given either with it or afterwards,
is a method that has not perhaps been applied sufficiently to nematode diseases.
If two drugs are thus given together, as for example copper sulphate and mustard
are sometimes given, the enhanced effect of their combined administration
may be due to the production by intestinal bacteria from one or both of them
of substances which, like the H 2 S just mentioned, render the parasites more sus-
ceptible. If we knew more about the chemical composition and permeability of
the nematode cuticle, we could extend our application of this principle.
Not less important in the treatment of nematode diseases is a preliminary
treatment, akin to that essential in the treatment of cestode infections, designed
to remove any substances by which nematodes may be protected from any anthel-
mintics which we may succeed in getting unaltered into the stomach and intestine.
The mucus secretion which nematodes provoke is one of the best protections of this
kind that they have, and one of the most serious obstacles to successful treatment.
We need much more work directed specifically to find out how this mucus may
be removed before anthelmintics are given. It is possible that methods of treating
human mucous colitis may be adapted for this purpose. It is certainly true that,
so long as we take no special measures to remove this mucus, the full effect of an
anthelmintics will not be obtained.
Mueller's work upon the mode of action of carbon tetrachloride is also a good
example of the physiological approach to the study of anthelmintics. He found
that this drug, being fat soluble, is concentrated in those parts of the nematode's
body where the fat deposits occur, namely in the muscles, along the nerve cords,
and under the cuticle. It is concentrated, therefore, just where its action is most
effective, and Mueller suggests that it paralyses rather than kills the nematodes,
so that this is why they are passed out of the host.
Mueller did not, how-
ever, find out why carbon tetrachloride permeated the cuticle. If we knew that,
the knowledge might suggest other drugs less dangerous to the host.
This physiological attitude to the problems of treatment is even more neces-
sary when we remember that not only the " adult " nematodes of some species, but
their parasitic larvae also do considerable damage. These often lie embedded in
the tissues or migrate through them or are carried by the blood to the lungs,
the muscles, the tendons and elsewhere. They cannot, therefore, be directly
treated by drugs given by the mouth. If we give these, they must be given with a
knowledge of their alteration in the intestine and the absorption of their deri-
vatives, and it is the latter which we direct at the nematodes, if we do not, indeed,
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inject them directly into the blood or elsewhere. We should know much better
what substances to inject, if we knew something of the physiology of these
parasitic larvae.
*
*
*
*
It must be obvious in the light of all these considerations, that the real
method of studying parasitic nematodes and the diseases they cause will not be
found until we can control in vitro not only their free living and their parasitic
larvae, but the mature worms themselves. Remote as this ideal may seem, we
should pursue it if only for the reason that attempts thus to cultivate nematodes
will add to our knowledge of their physiology. It will be objected that in vitro
experiments do not help us in the control of disease in living animals or plants,
and no one who has studied this question will treat this objection lightly ; but the
object of our in vitro control of nematodes will not be to gain information which
we may hope directly to apply to the treatment of disease, but information of
the kind upon which the whole of modern medicine and veterinary practice is
based. The future alone will show whether the patient study of nematode
physiology by every method at our command, will, or will not, increase
our control over them and their effects. It is certainly true that we ought to
make use of all these methods, whatever our views of their comparative
efficacy, if only for the reason that the parasitic nematodes are among the most
serious menaces to the continued success of our race and our civilisation.
REFERENCES.
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Rep. (17th) Dir. Vet. Serv. Anim. Indust.
Onderstepoort, Part II.
pp. 495-572.
GOODEY, T. 1933. Plant parasitic nematodes and the diseases they cause.
London, 306 pp.
HOEPPLI, R. 1927. "Über Beziehungen zwischen dem biologischen Verhalten
parasitischer Nematoden and histologischen Reaktionen des Wirbeltier-
körpers." Arch. Schiffs. u. Tropenhyg., XXXI, Beih. 3,205—290. (W.L.
1804.)
LAPAGE, G. 1933. The cultivation of infective nematode larvae on cultures of
Bacillus coli. Rep. (3rd) Inst. Anim. Path. Univ. Camb., 237—271.
(W. L. 18252b.)
—,
1933A. Cultivation of parasitic nematodes. Nature, Lond., CXXXI (3312),
583—584. (W. L. 14900).
—,
1935. The second ecdysis of nematode larvae. Parasitology, XXVII [in
the press]. (W. L. 16035.)
McCOY, O. R. 1930. The influence of temperature, hydrogen-ion concentration
and oxygen tension on the development of the eggs and larvae of the dog
hookworm, Ancylostoma caninum. Amer. J. Hyg., XI (2), 413—448. (W. L.
600a).
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MUELLER, J. M. 1929. Studies on the microscopical anatomy and physiology of
Ascaris lumbricoides and Ascaris megalocephala, Z. zellforsch., VIII (3),
361—403. (W. L. 23639b.)
SLATER, W. K. 1928. Anaerobic life in animals. Biol. Rev. III (4), 303—328.
(W.L. 2976b.)
SHEARER, G. D. & STEWART, J. 1933. The effects of nematode infestations on the
metabolism of the host. Parts I, II & III. Rep. (3rd) Inst. Anim. Path.
Univ. Camb., 58—129. (W. L. 18252b.)
STUMBERG, J. E. 1933. The detection of proteins of the nematode, Haemonchus
contortus, in the sera of infected sheep and goats. Amer. J. Hyg., XVIII (2)
247-265. (W. L. 600a.)
TALIAFERRO, W. H. 1929. The immunology of parasitic infections. London,
414+xv pp.
TAYLOR, E. L. 1934. "Field experiments on the immunity of lambs to parasitic
gastritis caused by a mixed infection of trichostrongylid nematodes. " J.
Helminth., XII (3), 143—164. (W. L. 11224b.)
—,
1934A. The epidemiology of parasitic gastritis in sheep. J. Agric. Sci.
XXIV, 192-208. (W. L. 109866.)
TAYLOR, E. L. & PURCHASE, H. S. 1931. Do penetrating nematode larvae assist
bacterial invasion from the bowel? Parasitology, XXIII (3), 301—309.
(W. L. 16035.)
VECLIA, °F. 1915. The anatomy and life-history of the Haemonchus contortus
(Rud.). Rep. (3rd & 4th) Vet. Res. S. Afr., 347—500. (W. L. 18640.)
THEILERIASIS OF YOUNG CALVES IN BAGHDAD DAIRIES.
BY
C. MACHATTIE*
Director, Veterinary Vaccine Lymph and Serum Institute, Baghdad.
(Reprinted from the Transactions of the Royal Society of Tropical Medicine and Hygiene,
Vol. XXVIII.No. 6.)
INTRODUCTION.
During the years 1917 to 1919, the authorities, with the object of improving
and augmenting the indigenous breeds of cattle and supplying the military and
civil populations with fresh dairy products, imported from India three thousand
five hundred head of Hansi and Sindi breeds; later, in 1921, sixteen Ayrshire
bulls were imported. The interval which has elapsed since then has proved that
these selected breeds cross well with the indigenous cattle and their progeny are
to some extent diffused over the country. Most of the best cows are on the Royal
farms, the Government farms and two large commercial dairies in the Baghdad
area.
This collection of the majority of the best cows into large herds under ex-
perienced supervision and within easy access of the laboratory, facilitates investi-
gation of diseases such as theileriasis, which requires close supervision of the
animals over a period of months. It is necessary to emphasize the fact that no
bovine has been imported into Iraq since 1921.
Early in 1934, a veterinary assistant was attached to the Royal farms in
Baghdad area. His duties were to tour these daily and see that certain measures
designed to effect a higher standard of animal management and hygiene were
being carried out.
On July 9th he arrived at the main dairy just as a herdsman was disposing of
the carcase of a young calf by the effective method of throwing it out for jackals,
scavenger hawks, etc., to pick clean in the course of the night. A postmortem
examination was made and the smears from liver and spleen were forwarded to
the writer with a report that the former organ was of a yellow color and the
spleen was enlarged. The calf was a female aged 13 days. Smear showed a 90 per
cent. to 100 per cent. invasion of the red blood corpuscles by ring-shaped haema¬
tozoa similar to those shown in Plat XXV, Fig. 1. In the spleen and liver were
*This paper is published by the permission of Farouq Beg El-Damlougi, Director
of Veterinary Affairs, Iraq, whose kindly aid and encouragement have made the
investigation possible. [ Ed. Trans. Roy. Soc. Trop. Med. and Hyg. ]
( 288 )
Ind. Jour. Vety. Sci. & Anim. Husb. Vol. V, Pt. 3.
PLATE XXV.
1
2
3
4
5
6
FIG. 1. Theileria annulata in peripheral blood of calf 18 days old.
FIG. 2. Schizonts (Koch's "blue bodies") of T. annulata in liver smear.
FIG. 3. Young schizont of T. annulata in mononuclear cell of liver.
FIGS. 4 & 5. Trypanosoma theileri in blood.
FIG. 6. Crithidial forms in squash preparation of tick (Hyalomma aegyptium) taken from calf
infected with T. Theileri.
THEILERIASIS OF YOUNG CALVES.
289
abundant and typical plasma bodies either in lymphocytic cells or lying free
(Plate XXV, Figs. 2 and 3). The appearances, when considered with the post-
mortem report on the solid organs, were sufficient to justify a diagnosis of acute
theileriasis.
GENERAL OBSERVATIONS.
The dairy was visited and the Indian jemadar, in charge of stock since the
war, questioned. A summary of his observations combined later with those
of jemadars and cattlemen at the other dairies is detailed in this paper, because
they show how easy it is for an almost symptomless disease, confined to young
calves, to exist in an area for years and yet completely escape the cognisance of
all except persons whose occupation necessitates their actually living amongst
dairy cattle the whole year round for a number of years sufficient to imprint on
their minds that regularly occurring annual inexplicable deaths have certain
points in common, such as a marked age factor and nervous disorders often asso-
ciated with fits and sometimes with jaundice.
The cattleman's experience of the disease is as follows :—
Every year approximately 75 per cent. of the total number of cross-bred
calves born in Baghdad dairies die before they reach the age of 1 month.
Mortalities on the grand scale generally commence in June and cease in
September, but in some years they may continue throughout the winter. Such
young calves die after an illness of only a few hours. The usual history is that in
the morning one calf or two are found dead showing no external signs of disease or
injury. Observed during the day, a calf apparently quite healthy collapses and
dies in a fit; or it may recover.
Several attempts have been made to utilize the veal of calves killed on the
first appearance of fits, but the flesh is ' wet' and generally the whole carcase
jaundiced, so that if the flesh is eaten at all, it is only by the poorest hangers-on
at the dairies. All of the cattlemen are familiar with a postmortem appearance
of a soft ' mushy ' liver of a peculiar yellow colour and an enlarged spleen. Most
surviving calves show a harsh staring coat and a general appearance of bad
health until they are about 3 months old, after which period they gradually put
on condition until at 6 months it is exceptional to find one which is not in robust
health. After they are 3 months old, only rarely do unaccountable deaths occur.
During the period approaching 2 and 3 months of age, about four calves per
month die at each farm. They are the better conditioned calves but show blood-
stained or streaked diarrhœa. Within a week to 10 days they either recover or
become very thin, show increased lachrymation and now and then bawl in an
unnatural manner, as if in terror; there is very marked depression, the animal
becoming heavy-eyed even to the extent of the eyes being closed; they become
prostrated and twist the head in unconscious fashion or press the head against
wall or any obstruction ; such cases with nervous symptoms rarely recover.
L