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.