Spatial distribution of Anopheles species across 3 different ecological zones in Ghana

Vector management of Anopheles mosquitoes in West Africa is challenged by limited data on distribution, species diversity, seasonal abundance, and lack of reporting mechanisms from sentinel sites. To improve the epidemiological risk assessment for Anopheles-vectored diseases, this study investigated the distribution and species composition of Anopheles mosquitoes in 3 ecological zones of Ghana and compared trapping methodologies. Adult Anopheles mosquitoes were collected monthly over 6 trapping sites from 2017 to 2021 using Centers for Disease Control and Prevention light traps with incandescent and ultra-violet (UV) light sources and Biogents Sentinel (BG) traps. A generalized Linear Mixed Model with a negative binomial distribution was used with the trapping method and month of collection as fixed effects, and the year of collection and site as random effects. Out of a total of 20,222 Anopheles mosquitoes collected, the majority were from the Sudan savannah zone (66.1%), while the Forest zone had the lowest count (1.8%). The predominant Anopheles species identified was An. gambiae s.l. (67.83%). There was a significant association between season and An. gambiae s.l. (P < 0.001), with higher numbers in the wet season than in the dry season. Furthermore, An. gambiae s.l. was less likely to be collected using UV-lighted traps compared to the incandescent-lighted traps (GLMM = -1.06, P = 0.0122). The results of this study will inform the development of evidence-based vector management strategies and contribute to the efforts to reduce the burden of vector-borne diseases in Ghana and West Africa.