Malaria transmission in the vicinity of impounded water: evidence from the Koka Reservoir, Ethiopia

The construction of dams in Africa is often associated with adverse malaria impacts in surrounding communities. However, the degree and nature of these impacts are rarely quantified and the feasibility of environmental control measures (e.g.,manipulation of reservoir water levels) to mitigate malaria impacts has not been previously investigated in Africa. This report describes entomological and epidemiological research conducted in the vicinity of the Koka Dam and Reservoir in Ethiopia. Key findings of the study include: substantially higher malaria case rates observed in communities close to the reservoir; greater abundance of malaria vectors found in community dwellings close to the reservoir as a consequence of breeding habitats created along the reservoir shoreline; and the association of faster falling water levels with lower mosquito larval abundance in shoreline puddles. These findings confirm the role of the reservoir in increasing malaria transmission and suggest there may be potential to use dam operation as a tool in integrated malariacontrol strategies.