CO129-410 - Governor Sir May - 1914 [3-5] — Page 242

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This mathematical relationship has been described by Profes- sor Sir Ronald Ross as the "flare phenomenon in connection

more particularly with outbreaks of Malaria

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a small increase in the number of infected mosquitoes in a district leading to a very large increase in the number of human cases, and the inference is that even though one "cannot hope to wholly exterminate either rats or mosquitoes, yet they may be reduced in numbers to such a level that infection among them becomes an almost negligible quantity. The analogy is not absolutely complete, however, because while the mosquito

obtains its infection from man the rat obtaine hie from

another rat, but that the same "flare phenomenon" does occur is proved by the above figures. One is able to reduce the mosquito population by removing or treating their breeding grounds, but the only method by which one can permanently reduce the rat population of a City is by reducing their food

supply.

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It has been established beyond question that to reduce the rat population of a City by poisoning and trapping is a purely temporary measure, so long as there remains an ample food supply; this is because any temporary reduction in num- bere is compensated for by increased breeding among the remainder, and within a few months the rat population returns

to its previous level, while there is the further danger, in

a Plague infected district, that the adult immune rats so

killed off will be replaced by young rate which are suscepti-

ble to Plague,

Hence we do not organize wholesale rat poisoning cam-

paigns in this Colony, but are careful to collect and examine

all rate found dead, or caught by house-holders and others

and we undertake the clearance of isolated blocks of buildings

whenever special circumstances warrant such a course. Our rat

returns therefore represent a more or less definite percentage

of the normal death-rate among the rat population, and the

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