192
Contagious Abortion of Cattle, Sheep and Goats
[VOL. XVIII, PART III,
Sections I, II and III. Epidemiology
Section I outlines the distribution of Brucellosis in India, and at the sale time distinguishes,
two forms of the disease viz., an imported and an indigenous. The former occurs in organized farms
whilst the latter is shown to have a remarkable incidence in its being almost entirely confined to
the villages of the humid Indian peninsula. The character of indigenous strains is peculiar. Bru-
cellosis of any sort was found to be rare in the arid north-west and fairly common in the south. Details
are given of both farm and village outbreaks.
Section II is mainly composed of epidemiological data for the various classes of Indian stock
(e.g., mean figures of frequency of abortion). Examples of exceptional occurrences are also given.
It is concluded that the descending order of the susceptibility amongst the various stock is European
cows ; crossbred European-zebu ; indigenous zebu ; buffaloes ; goats ; sheep.
Section III reviews, in the light of the field findings, the probable means by which Brucellosis is
spread in India, and it appears that elementary hygiene and climate are of supreme importance in
this respect. The extremes of the Indian climate offer an unusual opportunity for the study of the
effect of climate on the spread of the disease and a hypothesis that moisture is an almost essential
factor in the dissemination of Brucellosis is deduced from the distribution of the infection in this
country. This hypothesis not only fits the observed facts but is supported by an experimental de-
monstration that Brucella die much more rapidly in dry, than in moist, air.
Section IV. Bacteriology
Section IV records the examination of some 50 Indian Brucella strains. From the aspect of
virulence (white mice tests), antigenic structure and sensitiveness and tendency to dissociate these
strains are unremarkable. In one respect only do they differ from these of Europe, i.e., some 40 per
cent of all Indian field strains have typing characteristics intermediate between abortus and melitensis.
All village strains were of this nature and evidence is adduced which suggests this is an indigenous
strain.
Section V. Diagnosis
The standards for an all-India tube agglutination test are discussed and fixed in section V.
This test is intended for fine diagnosis but the use of the quick test is urged for survey work. The
reliability and specificity of these tests in Indian animals are reviewed and examples of the interpreta-
tion of field results are given. A number of optimum proportion tests fixing the best density for tube
antigen are reported and a simple method used for standardizing the density against reconstructed
dried serum is explained.
Section VI. Human infection
Section VI discusses the human aspect of Brucellosis in India. Reports of the prevalence of
melitensis infection in this country, published during the first decade of the century, are reconciled
with contemporary reports, asserting the scarcity of the disease by supposing that spread of infection
from the Mediterranean basin is obstructed by the interposing deserts, and that the infection referred
to in the earlier records was introduced into strictly localized areas by trooping movements from
Malta. Man's liability to infection by the indigenous strains of south India is discussed, but little
real evidence can be adduced in this connection.
Section VII. Control
Section VII deals with control of Brucellosis (a) by hygiene and (b) by vaccination. In India,
it is not usually feasible to control minor endemics by sufficiently frequent tests followed by disposal.
It has been noticed, however, that where zebu live more or less on the ranch system, in dry sunny
climate, Brucellosis is almost self-eliminating ; this tendency, augmented by a brief maternal segrega-