Incidence of malaria among children living near dams in northern Ethiopia: community based incidence survey.

OBJECTIVE To assess the impact of construction of microdams on the incidence of malaria in nearby communities in terms of possibly increasing peak incidence and prolonging transmission. DESIGN Four quarterly cycles of malaria incidence surveys, each taking 30 days, undertaken in eight at risk communities close to dams paired with eight control villages at similar altitudes but beyond flight range of mosquitoes. SETTING Tigray region in northern Ethiopia at altitudes of 1800 to 2225 m. SUBJECTS About 7000 children under 10 years living in villages within 3 km of microdams and in control villages 8-10 km distant. MAIN OUTCOME MEASURES Incidence of malaria in both communities. RESULTS Overall incidence of malaria for the villages close to dams was 14.0 episodes/1000 child months at risk compared with 1.9 in the control villages-a sevenfold ratio. Incidence was significantly higher in both communities at altitudes below 1900 m. CONCLUSIONS There is a need for attention to be given to health issues in the implementation of ecological and environmental development programmes, specifically for appropriate malaria control measures to counteract the increased risks near these dams.