The eradication campaign faltered, for historical reasons some of which are tentatively suggested above and which would be worthy of fuller study as an important part of recent medical history; it is one of those historical topics so intertwined with political and social history that an interdisciplinary approach would be fruitful — if the necessary documents could be made accessible, in India and perhaps in international organisations and subscribing government archives too.
Once the campaign faltered malaria seems to have diffused from the four foci suggested, the Kutch saltmarsh area and the hill-forest tracts of Madhya, Orissa and Assam. The role of wet years in areas normally arid, semi-arid or only moderately humid seems crucial in the diffusion process, and if the gaps in the rainfall anomaly maps can be filled we shall try to provide a more rigorous analysis of this relationship. Some humid and perhumid areas of high agricultural development, and dense or very dense rural populations, and one or two areas of considerable industrial and urban development like Greater Calcutta and nearby towns, seem so far to be happily little affected by the diffusion of malaria, even though as late as 1948 some including much of West Bengal were hyperendemic areas. It remains to be established by detailed studies if these areas are better prepared in some way — natural immunity must have faded especially in the considerable proportion of young people who have been born since malaria eradication was almost within grasp; or are they so far comparatively fortunate through some chances of the diffusion pattern?
Urban malaria, and one might say Anopheles stephensi malaria, is probably more widespread and more significant as an important public health problem than in former times. Once more the need for detailed local studies is clear.
It is important to re-read the introductory paragraph of this paper. The fiftyfold increase from 100000 to 5 million cases represents a sharp resurgence but the 5 million cases of 1975 and 1976, and few scores of recorded deaths, still represent a remarkable achievement as compared with the 75 million cases and 800,000 deaths a year at the time of Independence. From over 5 million in 1976 to 10 million in the first nine months of 1977, however, is a quite disquieting increase. If complacence did indeed play a part in the crucial years of resurgence in the late 1960s, it is unlikely to continue today in medical circles. One can only hope that politicians will take the issue seriously. Studies of the economic, educational and demographic impact of the resurgence may help them to do so.