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An Outbreak of Goat-Pox in Hissar District
[XVII
Spread of the disease
Some adult goats, which were being kept for another experiment in the same enclosure as the
pox-infected kids, were transferred to the main goat dairy one month after the last transmission
experiment. These goats did not catch the infection during five to six weeks they were in contact
with the artificially infected kids, and it was therefore presumed they were healthy. However, six
weeks after the adult goats were transferred, cases of goat-pox were detected among them and also
among the dairy goats. After the disease had subsided in the female stock, it spread to the males
which were being kept away from the dairy goats, to avoid infection. These observations seem to
suggest that the incubation period in goat-pox may be fairly long. According to Melanidi and Tzort-
zaki [1936], the incubation period in goat-pox is two to three days, followed by a stage of skin
eruption lasting for two to three weeks.
Mortality and lesions
From the reports of Disease Investigation Officers [1936-1945], it is found that in Bombay,
in 1938-39, there was 9 per cent mortality in one outbreak and 73 per cent in another ; two outbreaks
recorded in the United Provinces in 1938-39 and 1942-43 showed a mortality-rate varying from
15 to 20 per cent. Vishwanathan [1938-39] reported a 30 per cent mortality-rate in an outbreak
diagnosed in 1938-39. Kuppaswamy [1936] reports a mortality rate of 54 per cent attributing the
high percentage to unfavourable climatic conditions. lack of hygiene and unsuitable food. According
to Donation and Lestoquard [1936] discrepancies in the results of different workers on sheep-pox
are due to differences in the susceptibility of individual sheep and state of the virus, which has three
distinct phases of virulence from extreme to low. This is probably true in the case of goat-pox as
well. Altogether, in the original outbreak, 11 out of 179 female goats (39.7 per cent), 3 out of 13
male goats, 25 out of 100 kids (25 per cent), and 15 out of 30 (50 per cent) castrated kids, males,
suffered from the disease. The incidence was less in females and kids than in males and adults.
The outbreak lasted for about two months. There were only two deaths, viz. goat No. 59, which
developed gangreaous pneumonia as a complication, and an Angora buck which showed pox lesions
in the lung. Mortality was, therefore, low in this outbreak as compared with that reported by the
Disease Investigation Officers [1936-45] possibly due to low virulence of the virus.
In most cases pox nodules were generalized over the body, the teats and scrotum being parti-
cularly affected. There was rise of temperature lasting for 10 days or more, and considerable decline
in the milk yield during the active phase of the outbreak. A typical acute case was that of goat
No. 929. Vesicles were present all over the body, nostils, lips, udder and teats. Pneumonia
developed with rise of temperature to 107°F. This goat, however. recovered after a laborious treat-
ment. In some cases there was suspension of rumination, and rapid respiration. A tendency to
sit in the sun was observed in many cases. On the seventh day vesicles became black and by the
ninth day scabs had formed.
SUSCEPTIBILITY OF OTHER ANIMALS
According to the flock owners, sheep also died during the outbreak, but no affected sheep were
seen at the time of the visit. From the reports of the various Disease Investigation Officers [1936-45]
it seems that in outbreaks of goat-pox only goats were affected, though it is not clearly stated in all
cases that these were the only animals affected. According to Melanidi et al. [1936], cattle, horses,
rabbits and poultry are also susceptible to the virus of goat-pox while man is insusceptible, but it
is only in goats that the disease takes an epizootic form. Slagsvold [1938], on the other hand, states
that disease is readily transmissible among goats and sheep, and attempts to infect cattle, pigs, horses,
rabbits, guinea-pigs and poultry failed. Bennett, Horgan and Haseeb [1944] obtained a typical
pox syndrome in sheep, cows, and rabbits with goat-pox virus, though they found no immunological
relationship between the viruses of vaccinia, sheep-pox and goat-pox. A close relationship, however,
was observed between the viruses of goat-pox and contagious pustular dermatitis of goats. Hutyra
and Marek [1926] have also stated that in some cases transmission of goat-pox to sheep is successful
but that only an incomplete pox exanthema is produced at the point of inoculation.