16
In places where rats are very numerous plague may develop when
climatic conditions are adverse, i.e., when rat-fleas are scarce, but
plague tends to disappear with the advent of hot .dry weather.
It cannot "be too strongly emphasized that anti-rat measures, directed
towards the eradication of plague infection, can be prosecuted witli
most chance of success in the hot dry months when plague cases and
foci of infection are fewest. The relatively plague-free season should
synchronize with maximum anti-plague effort and not "be regarded as ;;
suitable time for a cessation of anti-plague measures.
Anti-plague measures can be grouped under four heads :—
(a) Rat elimination or the prevention of rat infestation. Th<c
comprises such modifications in the habits, customs t a,nd dwellings o!
a community as will result in a diminished rat infestation in the home
of the people and make the association between rats and men les.
intimate than at present.
(ft) Measures designed to protect the rat population of any givei
town or village from plague infection. These entail a clear under'
standing of the manner in which plague infection is carried from
place to place.
(G) Bat destruction designed, as is («), to diminish the chanoen
of infection, and to keep the rat population at so low a level that i>:
plague be introduced the severity of the resulting epidemic will be
appreciably diminished.
(d) If our efforts under these three heads fail to keep plague out.
it is left to try and render the human population immune to attack:
of the disease by means of inoculation, or to remove the population
at risk from close association with infected rats. The latter involve*
the evacuation of infected dwellings and the provision of temporär}
accommodation outside the rat-infested, plague-infected area.
Measures included under (a), (6) and (c] can be carried out at any
season of the year ; measures under (d~) are generally applicable onl\
in the plague season.
Segregation of the sick is not essential. For all practical purpose.-
the patient suffering from bubonic plague is not ca,pable of infecting
those in close attendance on him. Such a statement is not true oi
pneumonic plague. Small outbreaks of this disease, which is extremely
infectious, are occasionally experienced in India. These are, however,
of infrequent occurrence and of small moment when compared with
the incidence of bubonic plague.
It will be noted that of the four ' components ' of a plague
epidemic, viz., the plague bacillus, the rat-flea, the rat, and man, only
the rat and man have been specifically mentioned in this preliminary
'discussion of preventive measures. The plague bacillus is so short-
lived outside the body of either the rat-flea, the rat, or man, that
for practical purposes it need not be considered as possessing ai;
independent existence. Similarly, the welfare of the rat-flea is so
dependent on the plentiful supply of rats which they parasitize, and
has so short a life apart from its proper host, especially if it be infected
with plague, that ' anti-flea ' measures received no specific mention.
Such measures will be referred to when (b) is under detailed consi-
deration : they have very decided value and should in no wise be
overlooked,