Abstract
The role of in situ rain water harvesting (RWH) in water resources conservation is well recognized in semiarid areas, such as the highlands of northern Ethiopia. However, in fringe areas of malaria endemicity, the potential impact of such schemes on vector populations and malaria transmission is not well documented. We therefore investigated the impact of such environmental interventions on Anopheles vector breeding and malaria burden, in a cross sectional survey undertaken in March/April 2005 in 4 villages in northwestern (3 in Hadegti and Hibret subdistricts; (s.d) 1800masl.) and central (Endachewa s.d.; 2050masl) zones of Tigray, in northern Ethiopia, where large scale construction of half-moon ponds (HMP) and ditches was in progress. A total of 990 blood slides taken from under 10 children revealed 268 infections of which 90.7% were P. falciparum, 7.5% P. vivax and 1.9% mixed. All of these were from Hadegti and Hibret s.d. where HMPs predominated, revealing a slide positivity rate of 35.6% (range 30.7 – 41.7%) and 3.6%, respectively. The majority (>77%) of the malaria positive cases resided in households located within 750 meters of the RWH structures, indicating that proximity to mosquito breeding sites was an important determinant of malaria in the villages. Over 33.8 % of the aquatic habitats in these villages were colonized by Anopheles aquatic stages, of which all were identified morphologically as An. gambiae sensu lato (presumably An. arabiensis). HMPs were found to be more productive than the smaller ditches, where water stayed longer for the aquatic stages to reach maturity to the adult mosquito. Hence, such environmental interventions require due consideration and need to be integrated with appropriate malaria control strategies. Key words: In situ Rain water harvesting, Malaria, Anopheles arabiensis, Tigray, Ethiopia.
Highlights
In the Tigray highlands of Northern Ethiopia, the role of in situ rainwater harvesting (RWH) in water resources conservation is well recognized
This paper presents the results of an investigation carried out in March/April 2005 on the impact of these structures on vector breeding and malaria transmission in selected villages of Tigray, northern Ethiopia
The present study showed that construction of in situ rain water harvesting (RWH) structures aimed at water resources conservation have the potential to increase the transmission of malaria substantially, if built near human habitations
Summary
In the Tigray highlands of Northern Ethiopia, the role of in situ rainwater harvesting (RWH) in water resources conservation is well recognized. (Getachew Alem, 1999), these were supplemented by different RWH structures [e.g., semicircular micro catchments (half-moon ponds (HMPs), ditches, trenches, etc.], aimed at intercepting runoff water and improving infiltration and ground water recharge, thereby ensuring availability of water in springs and shallow wells. Farmers cultivated their crops behind earthen barriers and ditches to increase their crop yield (Desta Gebremichael et al, 2005; Mintesinot Behailu and Mitiku Haile, 2002; Nyssen et al, 2004). This paper presents the results of an investigation carried out in March/April 2005 on the impact of these structures on vector breeding and malaria transmission in selected villages of Tigray, northern Ethiopia
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