Malaria outbreaks in new foci in Sri Lanka

During its Malaria Eradication Programme (1958-1964) Sri Lanka spectacularly reduced its malaria incidence from around half a million per year to 17. Regrettably, this magnificent achievement could not be maintained, and malaria once again reached epidemic proportions in some areas. Of particular concern however, has been the emergence of new foci of malaria around the hill capital, Kandy, discussed here by Manel Wijesundera. The new outbreaks seem intimately related to hydrological changes brought about by major irrigation and hydroelectric schemes on the Mahaweli river. The priority for such schemes is not, of course, to flush out the pools where mosquito larvae thrive, but to divert water for irrigation and power generation. In parallel, human migration between malaria endemic and non-endemic areas - stimulated by the resettlement required by the dam reservoirs - has contributed to increased malaria transmission. In a sense therefore, this story is a classic of health impact overlooked in favour of agricultural and industrial development. But whereas most documented cases relate to extensive flooding causing an increase in vector breeding sites and so exacerbating disease transmission, this story is just the opposite. Here, it is reduction in water flow that has promoted an increase in vector breeding.