Genetic identity, human blood indices, and sporozoite rates of malaria vectors in Gaa-Bolorunduro, Kwara State, Nigeria.

INTRODUCTION: To identify the specific Anopheles mosquito sibling species responsible for malaria transmission, determine their vectorial potential, and predict suitable control measures, this study investigated genetic identities, human blood feeding, and sporozoite infection rates of endophilic Anopheles mosquitoes in Gaa-Bolorunduro, a cattle rearing community in Kwara State, Nigeria. METHODOLOGY: Monthly pyrethrum spray collections of Anopheles mosquitoes were conducted for one year in addition to PCR characterization of sibling species and ELISA probing of human blood meal and sporozoite infections. Mean numbers and human blood indices (HBI) of the different Anopheles sibling species identified were compared. RESULTS: The total of 668 PCR-identified mosquitoes comprised 50.8% An. arabiensis, 46.7% An. gambiae, and 2.5% An. coluzzii. Annual mean numbers of An. arabiensis was significantly higher (p = 0.001) than An. coluzzii but not An. gambiae (p = 0.602). Proportions of An. arabiensis found with human blood (0.29) were lower compared to An. gambiae (0.72) and An. coluzzii (0.75). However, the annual mean HBI of An. arabiensis was not significantly higher than An. gambiae (p = 0.195) and An. coluzzii (p = 0.249). Plasmodium falciparum sporozoite infection rate was 1.6% in An. gambiae, 0.9% in An. arabiensis and 0% in An. coluzzii. CONCLUSIONS: The prevalent An. arabiensis and An. gambiae mosquitoes found indoors, despite the outdoor cattle population barrier, could be targeted by community-scale utilization of long-lasting insecticide-treated bed nets. Further studies on outdoor mosquito surveillance and bovine blood meal identification are required for the recommendation of suitable complementary vector control measures for the community.

Detection and Co-occurrence of kdr (F1534C and S989P) Mutations in Multiple Insecticides Resistant Aedes aegypti (Diptera: Culicidae) in Nigeria.

The outbreak of yellow fever virus transmitted by Aedes aegypti has been of major concern in Nigeria, this mosquito also transmits several other arboviruses globally. The control of many vectors of mosquito-borne diseases relies heavily on the use of insecticides. Therefore, constant monitoring of insecticide resistance status and associated mechanisms is crucial within the local mosquito population. Here, we determined the resistance profile of adult Ae. aegypti from Majidun and Oke Ota communities, Ikorodu Local Government Area of Lagos State, Nigeria to different classes of insecticides using WHO procedures. The resistant phenotypes of Ae. aegypti were screened for the presence of kdr mutations F1534C, S989P, and V1016G, which have been implicated in insecticide resistance in yellow fever vectors. A high level of resistance to DDT and pyrethroids was recorded in Ae. aegypti in this study, although possible resistance to deltamethrin, one of the pyrethroids was reported in one of the locations. Resistance to bendiocarb was recorded in the Majidun community while Ae. aegypti in both locations were susceptible to malathion. The presence of F1534C mutation associated with DDT and deltamethrin resistance in Ae. aegypti population, and the presence of S989P mutation were detected singly and in co-occurrence with F1534C for the first time in Africa, while V1016G mutation was not detected in this study. The role of these mutations in resistance phenotype expressed in Ae. aegypti in larger populations needs to be established.