122

Report on Kála-ázar.

sign of cessation of its spread over a series of twenty years,
as this epidemic has, and absolutely depopulating certain
tracts of country? If anchylostomiasis could do this, then the
St. Gotthardt tunnel outbreak should have caused such an
epidemic when the infected workers dispersed to their homes
on the completion of the work, for it is recorded that hundreds
and thousands of them suffered. Was this the case? Lutz
writes:

      "As for the Gotthardt tunnel epidemic, it seems to have dis-
appeared in loco after the completion of the work. The infected
labourers were scattered elsewhere, and afforded opportunities of
observing the disease in still wider circles; yet these do not seem to
have given rise to any fresh epidemic outside Italy."

      Again, both the observations of Dr. Dobson and myself
show that the resident natives of Assam less frequently har-
bour the anchylostomia worms than do the coolies imported
from Bengal and other parts of India. Why then should
Assam only suffer from kála-ázar? It cannot be due to any
climatic reasons, for there is no essential difference in this
respect between Assam and Lower Bengal.

      Once more, if kála-ázar is due to a combination of these
two diseases, then it would follow that the severity of the
epidemic would be in proportion to the intensity of the two
factors in any given place or district. Let us see if this is
the case. Now it is generally recognised, and this was
also Dr. Giles' own experience, that there is plenty
of anchylostomiasis in Upper Assam, at least on the
tea gardens, while I find that the recent fever mortality
of the Sibsagar and Dibrugarh districts, which have not
yet been affected by the epidemic, has been higher during
the last four years than it was in the Nowgong district before
the appearance of kála-ázar there. Allowing then for the
slight improvement of registration during recent years, it
is evident that malarial fevers are at least nearly as prevalent
in these upper districts as in Nowgong, apart from kála-ázar,
while the fever-rate of Darrang was higher than that of