40
REPORT OF THE IMPERIAL INSTITUTE OF VETERINARY RESEARCH,
of a virulent strain might be taken as indicative of the degree of resistance possessed by
the animal. Groups of cattle were thus vaccinated with (i) dead avirulent, (ii) dead
virulent, (iii) living avirulent, (iv) living moderately virulent, and (v) living virulent
cultures of B. abortus. These animals were then to be tested at certain intervals in
convenient batches up to a year by inoculation of virulent cultures, and their blood exa-
mined daily by plate culture, simultaneously with " control," unvaccinated animals
treated with the same test material. Until the close of the year under report one test
only on the series of vaccinated animals had been completed, to test their immunity
after a three months' interval. The results indicated that the system of testing was a
valuable one, but unfortunately the decline in virulence after retention in the laboratory
of what had been the highly virulent strain used for test purposes made the results less
striking than they might otherwise have been. The work is still in progress.
(e) Coccidiosis. It was stated in the preceding Report that this subject was under in-
vestigation at Muktesar by Mr. Cooper, and that bovine coccidiosis seemed to be a wide-
spread infection in India. Thus, out of 90 hill bulls examined during the year under report
coccidia could be detected in the fæces by a floatation method (SHEATHER' S) on first examin-
ation in 88 bulls, and in the remaining two on the fourth and fifth examinations. Again, it
has been pointed out elsewhere in this Report that the infection is markedly resuscitated
by the onset of rinderpest, and that even a relatively mild degree of this infection is apt
to depress the intestinal mucosa to such an extent as to allow proliferation of and invasion
by the coccidia to assume the nature of a serious complicating affection. It is of interest
in this connection to note that out of a group of 199 hill bulls in which post-mortem lesions
of rinderpest were discoverable, there was evidence in 73, or 36.7 per cent., that coccidiosis
had been resuscitated to the status of a distinct clinical affection. Rinderpest appears to
exert a pronounced special action in exciting this phenomenon as compared with the action
displayed by other diseases, for in the case of 340 bulls examined post-mortem during the
same period and affected with diseases other than rinderpest evidence of affection with coc-
cidiosis was detected in 11 only. Infection with foot and mouth disease and large doses
of the organism of bovine contagious abortion did not seem to bring about resuscitation,
but certain irritant drugs, such as croton oil, appeared to possess this property. The
oocysts found in " carriers " were found to display considerable variation in size, from. 15
to 55 microns in diameter, and possessed thick capsules, but with the considerable increase
in numbers produced during resuscitation the size was found to become uniformly small
and. the capsules very thin. Difficulties were experienced in studying the sporogonous
development of the bovine oocysts, contrary to the ease with which this stage can be stud-
ied with rabbit coccidia.
Coccidiosis was also found to be a common infection in buffaloes, but no case of
resuscitation to the state of a clinical affection was found in these animals. In the fæces
of 88 rabbits examined post-mortem coccidiosis was detected in 69.
The subject of bovine coccidiosis seemed to warratn study under plains conditions for
the high incidence of infection among cattle used at the laboratory, derived from the
Kumaon hills, might be a local phenomenon, analogous to the known wide prevalence of
infection among cattle in the higher Swiss Alps ; hence, Mr. Cooper was instructed to
undertake systematic investigations of the condition during a four months' tour in what
was considered to be a suitable plains area, namely Assam. Infection of cattle was
found by him to be very widespread in this province, and exhibited the characteristics
displayed in Kumaon cattle. Cases of the natural affection were also discovered, and in
five oxen coccidia of what are believed to be a new species, belonging to the class
Isospora, were detected.
At Muktesar, coccidia were found in specimens from sheep, goats, pigs, dogs, cats,
rats, wild birds, and lizard, but none were found in an elephant, monkeys, mice,
bats, or fowls. During the Assam tour, they were found, as has been stated in cattle
and buffaloes, and also in sheep, goats, pigs (wild and domestic), dogs, foxes, cats (wild),
mongooses, hares (wild) rabbits, squirrels, rats, fowls (wild and domestic), geese, ducks
(wild and domestic), pheasants, pigeons, crows and other small wild birds, and gharials ;
they were not found in elephants, horses, deer, monkeys,bears, guinea-pigs, bats, partrid-
ges, snipe, wild doves, snakes, or fish (the number of some of the latter animals available
for examination was not large).
(f) Tuberculosis. It has been stated in the preceding Report that a preliminary experi-
ment carried out in the cold weather season of 1923-24 by Dr. M. B. Soparkar seemed to
point to the possession of a greater resistance towards tuberculosis by Indian cattle and
buffaloes than is found in European cattle. Hence, arrangements were made with agri¬