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XI.-SUMMARY OF CHIEF CAUSES AT WORK IN BRINGING
ABOUT A CONDITION OF INTENSE MALARIA IN
THE DUARS AND THE POSSIBLE REMOTE EFFECTS
OF THIS CONDITION.
(1) The Duars is not merely malarious; it is an area of malaria
hyper-endemicity, i.e., the conditions more or less general throughout
the year are those rarely seen except when malaria is epidemic. The
endemic index of malaria ranged from 50 per cent. to 100 per cent. and
remains persistently high from year to year throughout the whole dis-
trict, and a very large portion of the adult population suffers more or
less constantly from the disease.
(2) Black-water fever among Europeans, Bengalis, and to a less
extent among the coolies, is one of the consequences of hyper-endemic
malaria.
(3) The explanation of the special intensity of malaria in the Du-
ars is to be found in the fact that it is an example on a large scale of the
tropical aggregation of labour, a condition which plays an important
rô1e in the epidemiology of malaria in the tropics and especially in India.
(4) What largely determines existing conditions in the Duars is
its labour system. Indirectly it is also this system Which prevents the
use of any but the best class of labour such as that recruited from
Chota Nagpur.
(5) One of the chief causes leading to increased intensity of
malaria in the Duars is the fact that at the commencement of
their life in the district all new coolies are placed under the disad-
vantages imposed by the present labour system. The defects in the
system as they affect malaria are-
(a) The burdening of the new coolie from the very outset of life
in the Duars, when all his resources are necessary to enable
him to combat malaria successfully, with the repayment
of debts largely incurred in the course of his recruitment.
(b) Want of direct relations between the planter and the coolie,
the position held by the "sardar" and the making of