Species Composition and Plasmodium falciparum Infection Rates of Anopheles gambiae s.l. Mosquitoes in Six Localities of Kwara State, North Central, Nigeria
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Date
2021
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Abstract
ABSTRACT: Entomological data gathering is essential for monitoring malaria vector disease risks and selection of
appropriate interventions for the protection of exposed human populations. This study assessed the relative abundance,
species composition, and sporozoite infection rates of indoor resting An. gambiae s.l. malaria vectors in six communities
across 3 Local Government Areas in Kwara State, Nigeria. Total number of mosquitoes collected by Pyrethrum Spray
Catch method over a period of eighth months were correlated with rainfall values in the area. Plasmodium falciparum
sporozoite infection rates and sibling species identification of collected An. gambiae s.l. mosquito samples were
determined by ELISA and PCR respectively. Results showed a positive correlation (r = 0.639, p = 0.08) between rainfall
and numbers of Anopheles mosquitoes in the study areas. The overall composition of the An. gambiae s.l sibling species
in the collected samples from all the six communities showed the predominance of An. gambiae s.s 298 (75.3%) compared
to An. coluzzii 94(23.7%) and An. arabiensis 4(1.0%). However, the sporozoite infection rate of An. coluzzii (22.3%) was
higher compared to An. gambiae s.s (12.8%) and An. arabiensis (0%). Mean numbers of An. gambiae s.l mosquitoes were
significantly higher in Ilorin west LGA compared to Asa (F = 17.81, P < 0.001) and Ilorin East LGAs (F = 22.81, P <
0.001). Sporozoite rates of both An. gambiae s.s and An. coluzzii sibling species were higher in Ilorin West communities
(Aiyede 21%, Ogundele 32%) compared to Asa (Idi Emi 11.1%, Lasoju 5.1%) and Ilorin East (Oke Oyi 2.4%, Ote-efan
0%) communities. Prevalence of sporozoite-infected An. gambiae s.s and An. coluzzii indoors highlight the need for
effective insecticide treated bed-nets interventions to protect the residents from malaria risks. Higher numbers of An.
coluzzii in the swampy rice marshed Ilorin West LGA communities require larval source management as an additional
strategy for effective malaria vector control.