Co-occurrence of native and invasive malaria vectors in anthropogenic habitats in Metehara, Ethiopia: Opportunities for urban malaria control

Local data are essential to understand the threat posed by invasive Anopheles stephensi and native malaria vectors on urban malaria transmission. This study investigated key bioecological features of invasive and native malaria vectors in Metehara town, Ethiopia. In parallel with a case-control study assessing the impact of An. stephensi on urban malaria transmission, a bioecological assessment was conducted between November 2023 and October 2024. All potential larval breeding habitats were mapped, followed by bimonthly collections of immature and adult mosquitoes from randomly selected locations. Immatures were collected using standard dippers, and adults with CDC light traps, BG Pro traps, and Prokopack aspirators. Adult Anopheles were identified morphologically, while species identification of immatures, adult blood-meal analysis, and sporozoite detection were performed via PCR. Of 767 potential larval breeding habitats, 98.3% (n = 754) were anthropogenic, with the majority (95.2%, n = 730) accessible for oviposition, either fully (73.1%, n = 551) or partially (23.7%, n = 179). More than half were water storage containers for human consumption (37.3%, n = 281) or associated with construction (20.8%, n = 157), while abandoned containers, including discarded tyres, accounted for 22.3% (n = 168). Among anthropogenic habitats positive for Anopheles immatures (55.3%, n = 417), one-third contained both An. stephensi and An. arabiensis. Habitat positivity for An. arabiensis showed significant seasonal variation (likelihood ratio, LR = 46.96, P