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                                  Surra.                                  7

the outbreak. It has been proved that cattle harbour for
years the Surra parasite in their blood without showing any
outward symptoms, and that, although blood examination
fails to reveal the presence of the trypanosome, the blood
is still infective. In the present instance, four apparently
healthy cart bullocks were tested, and the blood from one of
the four gave Surra to the inoculated rabbit. Unfortunately
the native owners objected to their cattle being bled even
in a small amount and no further tests could be made.

The swampy land and jungle round the Bojiaghat stable
harbour Tabanidæ in large numbers before the rains, and it
is possible that these flies may have been the means of trans-
mitting the disease from cattle, but the disease continued to
spread rapidly after the disappearance of these flies. There
are also grounds for concluding that the Stomoxys could not
have been the sole agent in the transmission of the disease.
The zone in which the cases spread was confined to Kath-
godam and Bojiaghat ; the Stomoxys were of more general
distribution. The Stomoxys attacks in the day time when the
healthy horses were worked in contact with the affected ones.
The horses exposed to this infection during the day but
stabled apart from infected animals during the night, did not
contract the disease. Within the infected zones the ponies as
well as the bulls and buffaloes were badly bitten at night
by some insects (presumably a mosquito) which could not be
discovered at work.

Recently Mr. Leese has informed me that camels are
bitten in a similar manner at night, and that the Sarbans in
the Dera Ghazi Khan district send away their camels during
and after the rains to avoid the mosquitoes which are said to
be a cause of " fever and death. "

Among camels, Surra is following the extension of canal
irrigation, another fact which points to the probability of the
mosquito being concerned in the transmission of the disease.
Unfortunately the investigation of this outbreak was com-
menced at too late a date. It is proposed, if opportunity arises,
to continue the observations on the biting flies and mosquitoes
on this road during the present year.

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