What clinicians who practice in countries reaching malaria elimination should be aware of: lessons learnt from recent experience in Sri Lanka

The history of malaria in Sri Lanka dates back to the ancient kingdoms. During the long documented history of malaria in Sri Lanka several major epidemics were experienced. The most devastating of these was the epidemic of 1934 - 1935 during which the districts in the wet zone and the intermediate zone experienced high incidence resulting in nearly 1.5 million patients and 80,000 deaths. In the last two decades, major epidemics were encountered during the years 1987 and 1990/92. Major natural determinants of malaria epidemics in Sri Lanka have been the monsoon rains especially the North East monsoon, and also unusually dry weather leading to pool formation in rivers and streams [1,2]. Following the introduction of dichloro-diphenyl-trichloroethane (DDT) for mosquito vector control, there was a record reduction in the cases of malaria, with just seventeen cases in 1963 [2,3]. A similar scenario was experienced in Crete after the introduction of DDT in 1939 reduced malaria cases to undetectable levels within five years, enabling discontinuation of spraying DDT and declining malaria control activities [4]. However, within a matter of few years there was a resurgence of malaria in Crete due to the emergence of DDT resistant vector species [4,5]. Sri Lanka also experienced a resurgence of malaria in about five years. A massive malaria epidemic was experienced during the years 1967 - 1969 due to relaxation of surveillance. Although the exact mechanism is not known, several factors were thought to be contributory towards the failure. Persistence of several undetected foci of malaria transmission, extensive intra-country population movements particularly related to gem mining, lack of adequate financial support from the authorities at the time when the incidence was extremely low are thought to have contributed to this [2]. Since then, malaria became entrenched as a major illness in the island causing several hundreds of thousands of cases each year and many deaths.The Anti