MUKTESAR, FOR THE YEAR ENDING THE 31ST MARCH, 1927
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test (cross-agglutination, absorption tests) have been found to vary in
" type," so that on direct comparison at the laboratory with the four
serological types differentiated by MEYER among Bacillus abortus-
melitensis strains there have been found types to correspond with each.
This finding, in the light of what is known regarding the differential
properties of types among other micro-organisms (e.g., pneumococcus),
is considered to be of significance in the preparation of cultures for
vaccination. The vaccine now issued from the laboratory comprises
representatives of each type, which have lost their virulence completely
through long sojourn in artificial media. The mixed culture is grown on
agar slopes, to be emulsified for use as a live vaccine immediately prior
to use by the field workers.
Abortion in mares. Research upon this affection has also been noticed
in previous Reports. Large numbers of agglutination tests for the diag-
nosis of the common causal organism (Bacillus abortivo-equinus) have
been undertaken during the last six years at the laboratory, and an
attempt made to control the disease in certain important studs by the
periodical testing of all equines and the segregation of infected animals.
This work has been difficult, on account of the considerable gradation
in the intensity of the reactions observed among animals in infected
studs, so that it is difficult to distinguish always with certainty animals
that are infected from those that are healthy. The tendency to per-
sistence and considerable spread of the affection seems to vary very
much with the locality upon which brood animals are kept: in certain
establishments where there is much close grazing the tendency is for
the disease to persist in a virulent form: on others where the animals
are well scattered or are largely fed with cut fodder the proportion of
infection observed is often very high, with a low incidence of actual
abortion. The policy of segregation has been persevered in on one
large establishment (the Hissar Farm) for five years, but the results have
been disappointing. Some animals have been noticed to carry infection
for as long as two years, and afterwards become re-infected shortly
after they have been declared clean. It is also likely that organisms
of the Bacillus coli type are frequent concomitant or additional
causes of infectious abortion, as has been demonstrated in other parts of
the world. Vaccination prior to service with dead B. abortivo-equinus
has not been entirely successful. With the knowledge that the immu-
nity conferred after a single vaccination with members of the para-
typhoid group of bacilli does not much exceed two months and the indi-
cations published by such authorities as MIESSNER on this affection, it has
now been resolved to treat the brood mares on heavily infected estab-
lishments by repeated vaccination, once every two months, throughout
the period of gestation, except during the latter months.
Strangles. Attempts at prophylactic vaccination against this disease
were continued during the strangles season covering the cold weather
of 1925-26 at the Army Remount Depôts, Mona and Sargodha. The
incoming batches of young stock were divided into three lots:—(a)
to be treated by so-called pyo-vaccination; (b) to be inoculated with