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CHAPTER VIII.
FINAL CONCLUSIONS REGARDING MALARIA PREVENTION
IN BOMBAY.
447. In the preceding Chapters the prevalence and distribution of
malaria on the Island of Bombay have been discussed ; the causes responsible
for the existence of autochthonous malaria, in other words, the species of
anopheles mosquito which spreads the disease, have been described, their
breeding places have been examined, and their general distribution in the City
studied ; and the factors which tend to produce fluctuations in the intensity
of malaria from year to year have been considered. The measures which have
been adopted from time to time with a view of mitigating the disease have been
described ; and the cost of such measures and the difficulties to be encountered
in putting them into practice have been reviewed at some length ; and it only
remains to summarise as clearly as possible the final conclusions that have
been arrived at regarding the problem of malaria prevention in Bombay.
448. In the chapter on " Malaria in Bombay " it was shewn that, though
not nearly as prevalent in Bombay generally as in many parts of India,
the disease is present in every part of the Island ; but while infections are
uncommon and as a rule exceedingly mild in the north they are prevalent and
severe in the south ; and although malaria does not appear to be directly
responsible for a very heavy mortality, probably under a thousand deaths per
annum in ordinary year?, there is reason to suppose that it gives rise to a great
amount of sickness, from 60 to 75 per cent. of all fever cases being due to the
disease. The resulting loss to the City amounts, on the average, to a sum, of not
less than Rs. 12,00,000 to Es. 13,00,000 per annum.
449. The many thousand sufferers from malaria are drawn from every
class of the population, the rich as well as the poor; but of the different com-
munities the Pársis appear to shew proportionately the greatest evidence of
malaria infection ; and the results of this are reflected in the high percentage
of enlarged spleens among Pársi children, the relatively larger spleens among
these children in cartain areas, and the general low vitality of the race,
indicated by their failure to shew a natural increase, no great excess of births
over deaths taking place among them from year to year.
450. In the chapter on " Mosquitoes " it was proved that the commonest
anopheles in the island (N. rossi) plays no part in the spread of the disease ; but
Major Liston's discovery of the part played by N. stephensi in the spread of
malaria was confirmed; and it was shewn that the distribution of this mosquito
and its breeding places in the City coincided in a remarkable manner with that
of the relative prevalence and intensity of malaria.
451. As regards the malaria epidemic of 1908, the occurrence of which
suggested the need for an investigation, it has been shewn that, the cause of the
outbreak was neither the importation of the disease nor a wave of malaria passing
over India, but the previous existence of many hundreds of breeding places of
Neocellia stephensi in the City, each of which formed a centre of infection. In
this way many thousand people became infected, and from time to time, as local
conditions were favourable to its spread, malaria increased both in prevalence and
intensity. In 1906 and 1907 there were undoubtedly very many thousand in-
fected persons in A., B. and C. Wards, and the sudden rise in the prices of food in
the latter half of 1907 helped to intensify existing infections, pre-dispose to
relapses and generally favour the spread of malaria. In 1908, in spite of a short
rainfall, the distribution of the rain and general climatic conditions appear to
have been favourable to the production of large numbers of N. stephensi, and
this, occurring at a time when very large numbers of people in the City were
already infected with malaria, caused a great intensification of the disease, which
was enhanced by the further rise in the prices of food in September of that year.