SEVERE AND WIDESPREAD OUTBREAK OF RINDERPEST      103

progeny that have grown up in the interval that the' virus ' finds a medium at
hand for its ready propagation and, concomitantly, progressive exaltation of its
disease-producing properties."

This explanation of Edwards applied in a remarkable degree to the suscep-
tibility of the farm stock which had remained free from this disease for a number
of years.

According to Haupt it requires from 5 to 6 weeks before the disease affects all
animals of a herd consisting of 15 to 20 animals. Consequently rinderpest did
not spread very rapidly in large herds of the farm in the outbreak under report.

                    CONTROL OF THE OUTBREAK

Kerr and Menon [1934] report that goat blood virus alone and goat tissue
vaccine alone was used successfully on an extended scale in face of the disease
in Bengal, and similar conditions being the experience in this province, it was
decided to control the outbreak by means of goat virus alone vaccination.

To commence with, it was decided to immunise the female produce at Kher-
wan which were then free from infection. These inoculations at Kherwan were
meant to serve a dual purpose ; firstly to immunise the animals which were becom-
ing once more susceptible on account of the passing off of the serum effects and,
secondly, to study the nature of the reactions to be expected in the main herd.
Consequently 1,151 heifers and 33 bullocks were inoculated with the goat virus.

It was then decided to tackle the main infected herd where goat tissue vaccine
was brought into use. Any animal exhibiting the slightest signs of ill-health
was excluded from the vaccine inoculations and segregated for observation. In
all, the following number of incontact animals were vaccinated :—