Morphological and molecular characterization of endophilic Anopheles gambiae complex, in Itu Local Government Area, Akwa Ibom State, Nigeria

Abstract

Malaria is still regarded as a major public health problem in sub-Saharan African countries. Anopheles mosquitoes have been implicated as the major malaria vectors. However, species abundance, composition and distribution vary between different ecological zones. This study investigated the composition and distribution of Anopheles gambiae mosquitoes in Itu Local Government Area, Akwa Ibom State, Nigeria. Adult Anopheles mosquitoes were sampled bi-weekly from 15 randomly selected houses each from three communities in the study area by pyrethroid spray capture (PSC) method. Adult Anopheles species were identified morphologically and sibling species were further subjected to species- specific polymerase chain reaction (PCR) typing. A total of 269 female Anopheles species were caught between July and December, 2015. The study indicated significant (p<0.05) abundance of Anopheles gambiae siblings, with An. gambiae s.s recording 219(81.41%) followed by An. arabiensis 32(11.90%). A proportion of the samples were unidentified 18(6.69%). There was a significant difference (p<0.05) in the distribution of A. gambiae complex over the period of the study with a peak in September 89(33.01%). Anopheles mosquitoes were more abundant in Itu Oma 120(44.66%) than West Itam 98(36.43%) and East Itam 51(18.96%). The study also recorded significantly (p<0.05) higher rate of blood engorged female Anopheles (54.05%). This finding showed that An. gambiae s.s was the predominant malaria vector in the area and also, the incidence of malaria been likely to increase during the wet season. Therefore, vector control must be carried out in these communities to reduce the number of these indoor biting mosquitoes. This study therefore, will be useful as baseline data to help design strategies for malaria control in Itu Local Government Area and also facilitate the success of the ongoing effort on the malaria control programme in the State.

Keywords: Malaria; Anopheles, morphological; molecular; characterization; Akwa Ibom; Nigeria.