Studies on Anopheles Mosquitoes Host Preference and Malaria Transmission Intensity Using Immunological Diagnostic Methods in Gilgel-Gibe Dam Area, Southwestern Ethiopia

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Addis Ababa University


The Host feeding pattern and sporozoite rate of Anopheline mosquitoes were determined for mosquitoes collected from September to November 2010 in Gilgel-Gibe hydroelectric dam area, southwestern Ethiopia. Mosquitoes were collected from 16 villages surrounding the dam by hand-capture and light trap catches. Mosquitoes resting outdoors were also collected from potential natural resting sites and artificial pit shelters. Overall, 520 anopheline mosquitoes were collected. Anopheles arabiensis was the most predominant (88.65%) species followed by An. coustani s.l (7.12%) and An. demelloni (4.23%). All the 520 mosquito specimens were tested for circumsporozoite protein (CSP) and host feeding pattern using ELISAs. Of those tested for CSP, 10 specimens were found positive for Plasmodium vivax infection. None were found positive for P. falciparum. The CSP rate was 1.92 and entomological inoculation rate (EIR) was 9 infectios bites/person/month. Moreover, a single specimen of An. coustani s.l was screened positive for Plasmodium CSP. Results of blood meal ELISA showed that An. arabiensis have a wider host range and more opportunistic feeder than the other two anopheline species. The human blood index (HBI) of An. arabiensis was 4.12%, but no human blood was found in the other two species. The host preference index and forage ratio were higher for Equine for all tested species, indicating that equine was the most preferred host by the three mosquito species. An. arabiensis fed more on equine, bovine and ovine than human though the number of humans was significantly higher in the study area. Thus, zoo prophylaxis can be employed as possible vector control strategy. Multiple blood feeding was observed in all the 3 mosquito species and this multiple blood feeding behavior especially, in An. arabiensis population might have resulted in elevated EIR in contrast to the low HBI. Keywords: Anopheles, Blood meal, ELISA, An. arabiensis , sporozoite



Anopheles, Blood meal, ELISA, An. arabiensis, sporozoite