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causes are usually at work, as in the case of a grain godown customarily
used for the storage of grain brought from a place which is perennially
infected.
6. It is unfortunate that no accurate record exists for any town in
this Presidency of the genesis and history of the plague epidemics which
have afflicted it, nor has any special attention been directed to the loca-
lities and buildings in which the outbreaks began, or to the sources from
which infection has been imported. Yet these factors should be well
known to the local authorities, and should be the very foundation of
their preventive policy. Recent inquiries have, for example, elicited the
following facts :-
(a) Salem district is regularly infected from the Mysore State
through Hosur, and once plague appears in that town, it is a matter of
a few weeks or even days for it to make its appearance in Salem town
itself.
(b) In Coimbatore town, Uppilipalaiyam and the weavers' and
chucklers' quarters are well-known foci of infection from which plague
spreads year by year, and the town itself is periodically infected from
Mysore State or from South Kanara.
7. It is obvious that preventive measures which ignore fundamental
factors of the kind can have little practical value. It is a needless
extravagance, for instance, to attempt to destroy the rat population of
a whole town instead of concentrating effort on the localities where the
rat population is most dense, or where grain or cotton from areas
known to be infected is habitually stored. Until exact information is
on record for every town which is subject to epidemics, as to the foci
and channels of plague infection, the preventive staff is groping in the
dark.
8. The first duty of a health staff is therefore that of investigation.
To illustrate the kind of investigation needed, plague mortality figures
for the five towns, Bellary, Coimbatore, Salem, Mangalore and
Vaniyambadi, have been collected for the twenty years, 1902-21, and
graphs have been prepared (attached to this memorandum), showing
the average monthly mortality in each. The first group demonstrates
the seasonal prevalence which plague exhibits everywhere. The second
group of graphs gives the actual deaths by months for the same period,
and illustrate the irregularity with which epidemics have appeared in
the towns in question. While perfect accuracy cannot be claimed for
the figures on which they are based, the graphs prove the need for
ascertaining why plague should break out in a given year and reappear
at irregular intervals of two, three or more years. There must be
some reasons for these irregularly occurring recrudescences and it is
only by intensive inquiry that the causes can be ascertained.
9. Experience proves that in towns and villages susceptible to
epidemics, infection usually spreads from grain dealers' stores, cloth
bazaars and petty shops which afford special facilities in the form of
food and shelter for the multiplication of rats. The first duty of a local
health authority is therefore to compile an accurate record of the
following points:-
(a) the location, method of construction of granaries for trade as
well as for household purposes, and their relation to the course of
epidemics,
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