Malaria past and present: the case of North Sulawesi, Indonesia.

The incidence and impact of malaria in North Sulawesi have declined both in the short term during the 1990s, and over a much longer timespan (though perhaps less continuously) since the end of the colonial period. The improvement already seems to have been well underway before deliberate vector control activities became extensive in the second half of the 1970s, and environmental changes affecting the Anopheles mosquito fauna, in particular the replacement of primary and secondary forest by permanent farmland, are probably the principal reasons for the long-term trend; other possible factors include the increasing use of antimalarial drugs. The well-documented decline in malaria incidence over the years 1991-1997, nevertheless, probably reflects the unprecedented scale of residual insecticide spraying in the province during that period, while the slight resurgence of the disease in the last three years corresponds to the subsequent cessation of house spraying as a result of the current economic crisis. Despite the evident importance of environmental change as a factor ameliorating the malaria situation in the long term, experience from the colonial era suggests that the prospects for deliberate environmental management (species sanitation) as an alternative malaria control strategy are poor.