Biology and transmission potential of malaria vector mosquitoes in Elabered sub-zone, Eritrea
Okbaldet, Yohannes Bein
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This study was intended to assess the biology and transmission potential of the malaria vector mosquitoes in Elabered sub-zone, Eritrea. Field collected Anopheles mosquitoes sampled during the malaria transmission season, from September to November 2000, were identified morphologically in the field. Morphological identification revealed that members of the An. gambiae complex were the most abundant and the only malaria vector species present during the study period. All the members of the An. gambiae complex were subjected to polymerase chain reaction (peR) assay and results showed An. arabiensis was the only member of the An. gambiae complex found in this area. Blood meal ELISA tests showed that 16.9% and 66.9% of 266 An. arabiensis were human and bovine fed, respectively. The percentage of mixed feeds, on both on human and bovine was only 3.8%. A total of 12.4% of the samples failed to react either to human or bovine anti-sera. None of the non-vector anophelines tested positive for human blood. Anopheles arabiensis in this particular area preferred to feed and rest outdoors rather than indoors, and biting was more intensive in the first half than in the second half of the night. Plasmodium falciparum infection was also determined using ELISA for 589 An. arabiensis specimens. There was no apparent monthly variation in infection rate, 0.5%, 0.8% and 0.7% for September, October and November, respectively. Based on the entomological inoculation rate derived from the hourly night bait catches carried out, during the whole transmission season, a villager could be exposed to 0.08 infective bites/night. Anopheles arabiensis in this particular area is susceptible to deltamethrin, lambdacyhalothrin, propoxur and DOT. However, permethrin resistant strains might be present and more tests at field level are required to verify the result and monitor the situation.