32
Brucellosis in India
in the spread of this disease. The branch of husbandry that is most likely
to affect the spread of Brucellosis in cattle is, undoubtedly, the hygienic
conditions of the animal's environment. Animals kept in semi-ranch con-
ditions or in sanitary quarters with proper drains and maternity wards are
obviously less exposed to infection than chose that are not. With regard to
climate, it is obviously much easier to keep quarters hygienic in sunny,
dry climates than in places with less sunlight and a high rainfall. Indeed, it is
believed that one of the most important factors affecting the spread of
Brucellosis is humidity and lack of sunlight, a belief based on the following
considerations:—
(1) The exposure of the Brucella organism to direct sunlight results in
automatic sterilization within an hour or two. (2) In general, sun-baked sur-
faces are more easy to keep clean than those that are wet or muddy. (3)
In dry climates animals can usually spend most of their time out-of-doors
and this avoids the dangers of overcrowding. (4) In good weather there is
less likelihood of animals becoming chilled.
Weight is lent to the validity of this belief and to the importance
of hygienic surroundings by the following observations :—(1) The diminution
of infection in the Punjab Grantee herds during the period that they have
been self-contained, well-managed units, run on semi-ranch conditions. (2)
The diminution of infection on the Military Dairy Farms, which runs parallel
with the improvement of buildings and the erection of maternity wards in
these institutions. (3) The distribution of village infection in South India, which
is in general greatest on the humid east coast and least on the arid Deccan
Plateau. (4) The fact that during the four rainless years at Hissar, abortion
in the Government farm was 50 per cent less than in the six previous years of
normal rainfall. (5) The extraordinarily high incidence of infection in
buffaloes in farms around Bombay.
Item (5) requires a little elaboration. In a certain buffalo farm near
Bombay, the annual abortion rate for the last 5 years has been 25 per cent
of the total breeding stock. This is by far the highest abortion rate yet en-
countered in India ; much higher indeed than the highest rate observed
amongst delicate European stock and some explanation of this unusual state
of affairs is needed. Apparently, the reason is that in this part of the country
buffaloes breed seasonally, i.e. the majority calves in the post-monsoon
month of September. Animals, therefore, are liable to abort from May on-
wards. Actually, however, most of the abortions occur in August and the
wave of abortions coincides with the occurrence of the monsoon, during
which all animals are closely confined, sometimes for weeks on end in warm,
humid stables, some of which have mud floors. It is hardly surprising, there-
fore, that in these conditions a disease should assume exceptional proportions.
The last factor thought to affect the spread of Brucellosis is phasic
susceptibility but, owing to the short duration of the present researches, it is not
possible as yet to estimate the importance of this influence.
The diagnosis of Brucellosis
Two methods of diagnosing Brucellosis are described in detail in the
appendices but this opportunity may be taken to clear up some misconceptions
concerning the Brucella agglutination test.