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Dynamics and trends of malaria in relation to anopheline vector mosquitoes ecology, distribution and kdr resistance in Gilgel-Gibe

dam area, EthiopiaDelenasaw YewhalawA, Wim Van BortelB, Luc DuchateauC, Niko SpeybroeckB

ADepartment of Biology, Jimma University, Ethiopia, B Institute of Tropical Medicine, Antwerp, Belgium, and CDepartment of Physiology and Biometrics, Ghent University, Belgium

Introduction Results …

Methodology

• Study area: Gilgel-Gibe hydroelectric dam area

• Study design: Longitudinal community-based

• Study villages: 16 villages (8 ‘control’ and 8 ‘at-risk’ villages)

Conclusion

Alongside potential advantages, development of water resources either for irrigation or hydropower generation may have negative impacts on health. A number of studies conducted reported that large dam reservoirs/ irrigation schemes can negatively affect the health of local population (Erlanger et al 2005; Keiser et al 2005; Steinmann et al 2006). No integrated epidemiological and entomological studies had been conducted around Gilgel-Gibe hydroelectric dam area (Ethiopia) before or after the introduction of the damThus, this study is designed to: 1) investigate whether the introduced dam influences malaria incidence and transmission dynamics due to ecologic transformations 2) explore whether the introduced dam has an impact on abundance and distribution of vector mosquitoes 3) determine whether the malaria vectors of south-western Ethiopia develop resistance against insecticides that are commonly used in malaria control program in Ethiopia

This is a PhD work done in the context of IUC-JU programme

Contacts: PhD student: delenasaw.yewhalaw@ju.edu.et; promoter: nspeybroeck@itg.be

Results

• Overall prevalence of infection was 10.5% with 60.3%, 39.2% and 0.5% cases due to P. Vivax, P. falciparum and pf + pv, respectively• The result showed a two-fold increase (12% vs. 6%) in malaria prevalence in ‘at-risk’ villages compared to ‘control’ villages

Malaria prevalence in under 10 children in Gilgel –Gibe area

Insecticide bioassay test in malaria vectors in Gilgel-Gibe dam area

Seasonal abundance and dynamics of An. gambiae s.l in ‘control’ and ‘at-risk’ villages in Gilgel-Gibe hydroelectric dam area, southwestern Ethiopiatt

Distribution of anopheline mosquito population by collection method in ‘control’ and ‘at-risk’ villages in Gilgel-Gibe dam area, southwestern Ethiopia

Knockdown resistance (kdr) mutation in malaria vectors in Gilgel-Gibe dam area

• West African kdr allele (L1014F) frequency was 98.5% • East African kdr allele (L1014S) was not detected

•Higher abundance of anopheline mosquitoes in ‘at- risk’ villages than ‘control’ villages •Higher malaria prevalence in ‘at-risk’ villages compared to ‘control’ villages and proximity to the dam was a predictor of infection•Communities living close to the dam were at higher risk of malaria infection and the dam posed health problem to communities residing in close proximity •Mosquito vectors developed resistance to 3 out of the 4 classes of insecticides used in malaria control

References