188
Contagious Abortion of Cattle, Sheep and Goats
[VOL. XVIII, PART III,
Buffaloes
Throughout part I, constant allusion has been made to certain peculiarities of buffalo abortion
whose specificity was held in question. The salient points recapitulated are (i) sharp epidemics
of buffalo abortion can often be connected with preceding heavy rains, (ii) when these epidemics
are primary and where the buffaloes are not co-habiting with cattle, it is unusual to find more than
a few doubtful Brucella reactors amongst the affected buffaloes, (iii) in exacerbations of minor ende-
mics, when buffaloes are co-habiting with Brucella-infected cattle, the reactor rate in buffaloes is
about half of that in cattle and the serum titres of the buffaloes are low compared with those of the
cows, (iv) towards the end of prolonged outbreaks of abortion in buffaloes Brucella reactor rates have
been noted equal to the normal rate in cows irrespective of whether the buffaloes are with cows or
not, (v) buffaloes seem slow to contract Brucellosis from co-habiting cows, (vi) at least one epidemic
of buffalo abortion has been investigated in which unusual symptoms have been noted.
It seems that these anomalies can be explained by one of three postulates, viz., (1) that the
abortions are the result of some effect of the rain, e.g., chill, of depression (2) that they are caused
by an atypically manifested Brucellosis, exascerbated by rain, (3) that they are due to an unknown
rain-invoked infection. The possibility of the chilling effect of rain being the unaided cause of abor-
tion seems, at first sight, remote, for there is usually a lag period of some weeks between the rains and
the epidemic. As, however, a similar lag is sometimes observed when abortions are plainly the sequel
of fevers, this possibility cannot be entirely discarded. Indeed, on deeper enquiry, this postulate
becomes more attractive, in as much as the two species in which unexplicable abortions connected with
rains occur, are the buffalo and the goat, animals which are liable to be severely affected by chilling.
It might be further argued that continuous rainfall enhances this effect by depressing the buffalo's
very sensitive metabolism over long periods. Brucellosis could be accepted as the cause, were Brucella
reactors constantly and adequately present in all epidemics, and the part played by the rain could
be explained by the hypothesis of ' a better infective dose being transmitted by fluids ' (p. 134).
But, if, in the face of so many poor agglutination reactions, an aetiology of Brucellosis is insisted
upon, then it must be conceded that, in primary outbreaks, the Brucella agglutination response of
buffaloes is bad. There is considerable data to be found throughout this paper which adds support
to this supposition ; furthermore, it is irrefutable that Brucellosis is at least intercurrent in many
epidemics, and, while, in this disease, the carrier-role of fluids seems a reasonable one, the preserving
value of humidity on the contagion has been demonstrated.
Finally, if neither of the preceding suppositions be tenable, then certain sporadic primary out-
breaks of buffalo abortion must be due to an unknown waterborne infection, for this is the only other
solution which fits the facts. Nevertheless, it remains a solution without an aetiology, and to de-
monstrate the difficulty of securing evidence of another causal factor the following case report is
cited.
In an epidemic of abortions among buffaloes co-habiting with and presumably infected by cattle,
the Brucella reactor rate in buffaloes was half that of the cows, the rate in the cows being normal.
In the buffaloes only, there were the following symptoms, which disagreed with the Brucella syndrome,
(1) abortions occurred much earlier in pregnancy than was normal for Brucella infected buffaloes,
i.e., at three months term (2) a proportion of buffaloes were emitting a purulent vaginal discharge,
(3) a few necrotic ulcers the size of a shilling were seen on the vaginal mucosa. Sabotage, plant-
poisoning and the sequel of vaccinations or febrile infections could be ruled out. The vaginal secre-
tions were examined for protozoa by the usual means and for bacterial infection by numerous small
animal injections and direct cultures. But no pathogen, including the Brucella microbe, could be
found. It is to be noted that the outbreak was preceded about one month earlier by exceptional
rains.
For the present, therefore, it is not possible to adjudicate between the three hypothesis, and
plainly, experiment should determine the true course of Brucellosis in buffaloes and the effect of their