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IMMUNOLOGICAL STUDIES ON PASTEURELLA [Vol. XXVIII, Part III,
Judging from the results of this investigation it would appear safe to assume
that the vaccine can withstand fairly high temperatures. In this experiment, the
vaccine had been kept exposed continuously to temperatures of 37°C and 40°C
for as long as ten days. In the normal course, transport of the vaccine is not likely
to take more than ten days and it would hardly ever be subjected to more rigorous
conditions than these.
(ii) Studies on the vaccine exposed to atmospheric temperatures. An additional
proof of the ability of the vaccine to withstand high temperatures during summer
months without losing its potency was obtained when about 34,000 doses of the
vaccine were despatched during the hot months of May, June and July from Muk-
teswar to far-off places such as Bombay, Poona, Secunderabad, and places in the
Punjab and Jammu and Kashmir in connection with field trials on the vaccine in
these areas. The vaccine was filled in amber-coloured bottles and was packed in
ordinary wooden boxes, which were transported from Mukteswar to the rail-head,
Kathgodam, by bus and further by passenger train. It took about 5-10 days for
the vaccine to reach its destination.
As many as 1684- animals were vaccinated during 1955 with the adjuvant vaccine
transported by bus and rail in the manner indicated above but not even a single
vaccinated animal died of pasteurellosis although there were several deaths due to
haemorrhagic septicaemia in the neighbouring villages where either the animals
had not been protected at all or were vaccinated with the commercial broth vaccine.
Similarly, during 1956, as many as 28,531 animals were inoculated with the adjuvant
vaccine which was transported during the summer months of May, June and July,
but only two animals died of pasteurellosis over an observation period of 5-7 months.
The remaining animals remained quite well throughout the monsoon season while
several deaths occurred amongst the unvaccinated animals as well as in the
animals protected with the commercial broth vaccine,
From the above studies, carried out under laboratory as well as field conditions,
it would appear that the adjuvant vaccine can be safely transported over long dis-
tances during the summer months without any appreciable deterioration of its
potency.
Duration of immunity
In an earlier paper Dhanda et al. [1956] had reported that under laboratory
conditions the adjuvant vaccine conferred adequate immunity in cattle for as long
as eight months which was the maximum period for which tests had been carried out
till then. Another immunity trial was carried out on five vaccinated hill-bulls at an
interval of nine months and 21 days following vaccination. The vaccinated animals
along with three healthy un-vaccinated hill-bulls were challenged with as severe
a dose of virulent culture as 1,000 million mouse M. I. D. All the five vaccinated
hill-bulls resisted the challenge whereas all the controls died of pasteurellosis. Fur-
ther immunity tests will now be undertaken at longer intervals.
Field trials
With the idea of studying the efficacy of the vaccine under field conditions
as many as 28,531 animals in four dairy farms and 38 villages having a history of
annual recurrence of haemorrhagic septicaemia, were vaccinated with the adjuvant
vaccine. The details of vaccination are given in Table VII.