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(b) the railway premises, their environment and the relation of
plague to such premises, and
(c) other contributory causes such as imperfect drainage, storage
of commodities or garbage conducive to the harbouring or feeding of
rats.
III.-PREVENTIVE MEASURES.
10. Preventive measures may be either A. Seasonal or B.
Permanent.
11. A. Seasonal Preventive Measures.-The seasonal measures to be
taken may be classed under four heads-(a) rat destruction, (b) cleanli-
ness, (c) control of movement of (i) goods and (ii) persons, and
(d) inoculation.
12. (a) Rat destruction.-It is doubtful whether rat destruction has
ever been thoroughly carried out in any district. There has been entire
lack of organization, there has been little supervision of ratters, and no
care has been taken to deal systematically with well-known infected
areas. In order to be effective, rat operations must be organized on a
large scale throughout the non-epidemic season and especially a month
or two before the date of probable reappearance. As already pointed
out, it is useless to attempt to destroy the whole of the rats in a town.
Intensive operations must be directed towards keeping down the rat
population in and around these areas known to be foci of plague
recrudescence. Traps and poison baits should be used alternately over
periods of about ten days, care being taken that baits and poison pills
are renewed daily. Energetic and sustained campaigns carried out on
these lines will help to keep the rat population at a low level, and a
reduced rat population, even if it remains -in proximity to man, is
incapable of maintaining a serious epizootic; but if sustained effort be
not secured, and if the campaign be not carried out systematically, the
results will be disappointing and will kindle the popular scepticism as
to the value of rat destruction. It is obvious that, if the best results
are to be obtained, the local health authorities must concentrate atten-
tion on these foci which investigation has shown to be the danger spots.
13. (b) Cleanliness.-Insanitary conditions and overcrowding favour
infestation by rats and are important factors in determining the
spread of plague, whilst persons who live under healthy and sanitary
conditions run but little risk. The habit of using the streets and lanes
as depositories for filth, refuse and garbage affords an abundant food
supply for the rats. Rats will not remain where they can get no food,
and special attention should therefore be paid to the systematic removal
of garbage and rubbish and the general cleanliness of dwellings, house-
drains, gullies, court-yards and their surroundings The improvement
of conservancy in towns and villages is one of the primary duties of a
local body, and the health staff should take every possible step to ensure
that this factor in the spread of plague does not exist in the area for
which it is responsible.
14. It would be of immense advantage to the public health of India
if the people generally could be brought to realize the importance of a
periodic cleansing of the home. It is not a process that involves
expense, All that is needed is a little trouble. It should be within
the power of local health authorities to educate public opinion in this