6
REPORT OF THE IMPERIAL INSTITUTE OF VETERINARY RESEARCH,
a similar period of time also showed that animals could be safely submitted
to this procedure of immunization during hot weather conditions on the
plains.
As in previous years the manufacture of anti-rinderpest serum con-
stituted the chief function of the laboratory ; 28,48,110 doses were issued
during the year, as against an average of 22,84,850 doses during the pre-
ceding three years. The increase in issues is attributable to a general
recrudescence in the number and severity of outbreaks of the disease
throughout India, which are treated by the Provincial veterinary authori-
ties by the application of the " serum alone " method.
The great bulk of serum production is now undertaken, as has been
stated before, at the plains branch laboratory, at Izatnagar, near Bareilly,
for reasons of economy, and the manufactured supplies are returned to
Muktesar for testing and cool storage prior to issue.
(b) Hæmorrhagic septicæmia of cattle. Much progress was made in
our knowledge of methods for dealing effectively with this second most
important disease condition of cattle in India. In affected districts,
notably in the Punjab, liable to seasonal visitations cattle are treated
preventively on a large scale by vaccination, based upon similar methods
of intervention to those adopted for combating human plague. The
local authorities report very favourably upon the efficacy of the system.
In other districts cattle are inoculated only in the actual scene of out-
breaks, with an anti-serum supplied from the laboratory, and the serum
treatment would appear to render conspicuous service in cutting short
immediately the outbreaks. The research work done at the laboratory
has now culminated in the development of a very cheap and rapid method
of anti-serum production,by the simultaneous inoculation of the producers
(buffaloes) with a large initial dose of culture of living antigen of low
virulence and a suitable counteracting dose of serum ; curiously, rigorous
tests have proved that the use of antigen of low virulence leads to the
production of an anti-serum of as high potency as that obtained after the
use of. highly virulent antigen. A most powerful immunity is set up in
susceptible animals by the simultaneous treatment with anti-serum and
a small dose of living culture of degraded virulence.
(c) Contagious bovine abortion. The application of the agglutination
test to the milch cattle belonging to some of the Government Military
Dairies showed that about 50 per cent. are infected with the common
form of this disease, and about 20 per cent. abort, usually repeatedly.
Tests upon cattle belonging to the " grantee " farms of the Punjab,
however, showed that under " natural " conditions of stock raising in
India about 10 per cent. are infected, while none would seem to become
clinically affected with abortion. Efforts to vaccinate cattle at the Mili-
tary Dairies, by the inoculation of massive doses of living culture, whether
of low or high virulence, have hitherto been somewhat discouraging.
Steps are being taken to investigate more thoroughly the factors
governing the production of immunity against this harassing conditions.