J. R. HADDOW AND J. A. IDNANI 183
Blood is also infective from the time the temperature rises until the temperature drops in
chronic cases.
We have also to record negative results in transmission experiments with four Bhutia goats
(a long-haired variety from the Himalayan hinterland). Whether these goats were naturally immune
cannot be said, as these goats are only supplied to the Institute during the winter months. We
have also no information as to the natural method of transmission in local breeds of goats. It is
peculiar that, although in nature the disease seems to spread readily enough, healthy goats have
been left in contact with artificially infected ones at all stages of the disease for long periods without
acquiring the disease. Later, they were found to be fully susecp ble to artificial inoculation.
AETIOLOGY
The circumstances in which the disease was found led us to suspect a virus as the probable cause,
and filtration experiments with emulsions of nodules confirmed this suspicion. Infective bacteria-
free filtrates were readily obtained from Berkefeld V, Chamberland L1, L2, L3 candles. Cultural
examination for bacteria at the early stages of the lesions was also uniformly negative.
The virus is present in the skin lesions throughout the course and has been recovered from the
scabs more than three weeks after the original inoculation. Virus in dried scabs or in tissues stored
in 50 per cent glycerol remains viable for at least 16 months at 0—5°C.
IMMUNITY
Cross-immunity tests with several strains of pox virus from goats and sheep and with the virus
of contagious ecthyma of goats have shown that the virus now under consideration has no immuno-
logical relationship with these viruses. As already stated, all natural cases so far examined have
been fatal. In our series of passages a few goats inoculated by scarification have survived and this
led us to try the scarification of the skin of the ear as a possible means of inducing a non-fatal attack
of the disease. So far, ten goats have been inoculated by lightly scarifying a small area on the inside
of the ear. All showed a marked thermal reaction with local nodule formation. Six of these were
available for test six weeks to two months after the original inoculation and all were solidly immune
to an intravenous injection of skin nodule suspension. The serum of recovered goats possesses anti-
viral properties and may be used in conjunction with virus to produce active immunity. The immu-
nity following an attack lasts at least two years,—the longest period so far available for test.
DIFFERENTIAL DIAGNOSIS
The only description with which the disease under reference bears some resemblance is that of
Wallace [1935], who during the course of investigation on contagious goat pleuropneumonia encoun-
tered high mortality due to what he termed ' atypical or stone-pox.' The skin lesions observed
by Wallace were unlike classical pox and were probably similar to what have been described in this
article. The absence of vesicles and pustules, the case with which the virus can be filtered, together
with the absence of cross-immunity reactions, and the presence of the virus in the blood stream for
a prolonged period clearly differentiates this condition from goat-pox, while the widespread distri-
bution of the skin lesions, the presence of typical nodules and the absence of cross-immunity differen-
tiates this condition from contagious ecthyma. The presence of the nodules is of diagnostic signi-
ficance in cases where confusion with other infectious or contagious pneumonias of goats might arise.
SUMMARY
An acute highly fatal disease of goats characterized by specific skin eruptions is described. At
first, it was regarded as an atypical form of goat-pox, but detailed studies of the lesions and immu-
nological tests have made it possible to recognize it as a separate disease entity.
The causal agent is a filtrable virus which is present in the blood and skin lesions throughout
the course of the disease. It passes with ease a Chamberland L3 filter.