The upland taluks adjoining the Agency also suffer, though to a much less extent, from malarial fever. In 1869-70, before the advent of the theory that all malaria is conveyed by the anopheles mosquito, elaborate enquiries were made as to the prevalence and causes of the disease in these parts of the district, and the Sanitary Commissioner arrived at the conclusion that the fever in the plains was due to the northerly winds which sweep over the malarious forests of the hill tracts. He pointed out that the taluks which were most open to breezes from the sea had the least fever, while those which were most exposed to wind blowing across unhealthy jungles had the highest ratios of sickness and death from malaria.
The question had also been raised at that time whether the great increase of irrigation under the recently-constructed anicut was in any way responsible for the insalubrity of the district. It was known that in some places (the Punjab, for example) irrigation was invariably accompanied by malaria. Enquiries were therefore directed at the same time to the elucidation of this point. The conclusion arrived at was that the irrigation had had no effect upon the prevalence of malaria. The result of five years' registration of vital statistics 'demonstrates in a very clear manner that the intensity of fever in any taluk has no relation to the extent of irrigation of the land, but is solely due to its geographical position and its exposure to malarious winds during the north-east monsoon.' The irrigated taluks were in fact found to suffer in very varying degrees. For five years the death-rate in Rámachandrapuram taluk had been 11.9 per thousand, while in Amalápuram and Narasapur it was 6.5 and 4.6 per thousand respectively. The difference was attributed entirely to the position of the taluks, the former being exposed to winds from the north, while the latter are swept by sea-breezes.1[1] Theories regarding the dissemination of malaria have doubtless changed since those days, and vital statistics in rural areas are seldom sufficiently accurate to afford a firm foundation for debatable propositions; but the fact remains that the delta taluks (unlike irrigated areas in some places in this Presidency — the valley of the Tungabhadra, for example) are not greatly subject to malaria and are, in fact, the part of the district in which it is least prevalent.
Cholera, however, is endemic throughout the delta. It is chiefly conveyed from place to place along the lines of communication, that is, by the movement of persons affected with
- ↑ 1 Proceedings of the Madras Government, Public Department, June 14, 1871 and G,0. No. 143, dated 30th December 1872.
