Density, Diversity, and Resting Site as Preferences for Anopheles Coluzzii Predominance of Malaria Vectors in Four Urban Slums of Gombe Metropolis, North-eastern Nigeria

Abstract

Urban slums in sub-Saharan Africa represent high-risk environments for malaria transmission, yet vector ecology in these settings remains poorly characterized. Therefore, this paper investigated the density, diversity, and resting site preferences for Anopheles coluzzii predominance of malaria vectors in four urban slums of Gombe Metropolis, northeastern Nigeria. Entomological surveys were conducted over six months (2024–2025) covering dry (November–January) and rainy (June–September) seasons. Ten households were randomly selected from each slum. Indoor resting mosquitoes were collected using Pyrethrum Spray Catch (PSC) in human dwellings and Prokopack aspiration in animal shelters. Morphological identification was complemented by molecular characterization using multiplex PCR targeting the Anopheles gambiae complex. A total of 123 female Anopheles mosquitoes were collected across four locations. Morphological identification revealed An. gambiae s.l. (98.4%, n=121) and An. rufipes (1.6%, n=2). PCR analysis of 66 successfully amplified specimens identified Anopheles coluzzii as the predominant species (98.5%, 65/66, 95% CI: 91.9–99.8%), while Anopheles gambiae sensu stricto was rare (1.5%, 1/66, 95% CI: 0.2–8.1%). The distribution of PCR-confirmed An. coluzzii between resting site types varied across locations, with exclusive detection in human dwellings in Dawaki, dual detection in Ziringaza, and predominant detection in human dwellings in Tabra. Seasonal patterns suggested year-round presence, with variation in monthly abundance. This study provides preliminary evidence that An. coluzzii is a major malaria vector in Gombe urban slums, with observed variation in resting site distribution that warrants further investigation. The findings highlight the need for larger, more systematic entomological surveys incorporating standardized collection methods, blood meal analysis, and infection status determination to inform evidence-based vector control strategies in urban settings.