Heterogeneity in malaria transmission dynamics across eco-climatic facies in Manjo and Manengoteng, Cameroon

Objectives: Tailored vector control strategies require entomological insights specific to each ecological setting. In the borough of Manjo, such data are unavailable. Hence, this study aims to document entomologic data for this borough relating to the identity of vectors, their role in malaria transmission, and variation between different sites. Methods: Mosquitoes were collected using the human landing catches method and they were identified using specific keys and polymerase chain reaction. Infectivity was determined by enzyme-linked immunosorbent assay. Results: Overall, 1766 mosquitoes belonging to five genera (Anopheles, Culex, Aedes, Mansonia, and Erethmapodites) and five Anopheles species were collected. Anopheles represented 36.0% (n = 636) of these and Culex represented 58.1% (n = 1026). In Manengoteng, Anopheles funestus s.l. were more prevalent (60.3%), followed by Anopheles gambiae s.l. (24.5%), and showed more exophilic behavior. In Manjo, Culex quinquefasciatus (94.4%), which is more endophilic, was most abundant, followed by Anopheles gambiae s.l. (2.2%). A high density of Anopheles was registered during the rainy season (79.87%). Malaria was only transmitted during this season by Anopheles gambiae s.s. (entomological inoculation rate [EIR] = 0.05 ib/p/n), Anopheles funestus s.s. (EIR = 0.02 ib/p/n) at Manengoteng, and Anopheles coluzzii (EIR= 0.02 ib/p/n) at Manjo. Conclusions: High species diversity is driving persistent transmission despite widespread use of long-lasting insecticidal nets.