Effect of a large dam on malaria risk: the Koka reservoir in Ethiopia

Abstract

Summaryobjective To determine whether the Koka water reservoir in the Rift Valley of Ethiopia contributes to the malaria burden in its vicinity.methods Frequency of malaria diagnosis in fever clinics was correlated with distance of residence from the margin of the Koka reservoir. Annual as well as seasonal malaria case rates were determined in cohorts residing < 3, 3-6 and 6-9 km from the reservoir. Plasmodium falciparum risk was compared with that of Plasmodium vivax. A multiple variable regression model was used to explore associations between malaria case rates and proximity to the reservoir, controlling for other suspected influences on malaria transmission.results Malaria case rates among people living within 3 km of the reservoir are about 1.5 times as great as for those living between 3 and 6 km from the reservoir and 2.3 times as great for those living 6-9 km from the reservoir. Proximity to the reservoir is associated with greater malaria case rates in periods of more intense transmission. Plasmodium falciparum is most prevalent in communities located close to the reservoir and P. vivax in more distant villages. The presence of the reservoir, coupled with inter-annual climatic variations, explains more than half of the region's variability in malaria case rates.conclusion Large water impoundments are likely to exacerbate malaria transmission in malariaendemic parts of sub-Saharan Africa.keywords malaria risk, large dam, impounded water, Ethiopia, Africa

Climate Change and Highland Malaria: Fresh Air for a Hot Debate

“…distance to breeding sites Malaria has been associated with the presence and proximity of marsh areashence the name "mal aria" or "bad air"-since the earliest descriptions of the disease and its symptoms. Studies on the proximity of water bodies, either natural or manmade, showed that indoor vector densities were higher close to breeding sites (Lindsay et al 1995;Minakawa et al 2002a;Minakawa et al 2004) and that malaria risk was, consequently, increased in these areas (Bøgh et al 2007;Clarke et al 2002;Ghebreyesus et al 1999;Kleinschmidt et al 2001;Lautze et al 2007;Oesterholt et al 2006;Staedke et al 2003;Trape et al 1992). Interestingly, Clarke et al (2002) noted that, although risk in terms of exposure was decreased farther away from water bodies, clinical illness was more common, probably as a result of reduced immunity due to lower exposure to infective bites.…”

Energy and Human Health

“…Some studies have shown no impact of hydroelectric dam construction on nearby malaria (68), but most show an increase in risk (112,122,234 Policy on dams needs to balance the considerable health benefits of available energy and water management with local adverse health and social impacts (127,131,230). For this purpose, guidelines have been issued for equitable, atraumatic resettlement (229).…”

Impact of dams and irrigation schemes in Anopheline (Diptera: Culicidae) bionomics and malaria epidemiology

“…More examples of impoundments and malaria are found in Ethiopia. For example, the construction of the Koka dam was also associated with increased levels of malaria transmission and with P. falciparum becoming more prevalent in communities adjacent to the dam site 55 . Similarly, YEWHALAW et al 101 observed a higher proportion of P. vivax infections on children living in communities near the Gilgel-Gibe dam, but the proportions of P. falciparum cases were not significantly different for at-risk communities and villages farther away.…”

“…The authors highlighted that the water management of irrigated fields was the most influential factor that modulated the mosquito population dynamics 19 . LAUTZE et al 55 concluded using a GIS that the distance of the communities to the Koka reservoir in Ethiopia was one of the variables SANCHEZ-RIBAS, J.; PARRA-HENAO, G. & GUIMARÃES, A.E. -Impact of dams and irrigation schemes in Anopheline (Diptera:Culicidae) bionomics and malaria epidemiology.…”