Large-scale releases and establishment of wMel Wolbachia in Aedes aegypti mosquitoes throughout the Cities of Bello, Medellín and Itagüí, Colombia

Abstract

BackgroundThewMel strain ofWolbachiahas been successfully introduced intoAedes aegyptimosquitoes and has been shown to reduce the transmission of dengue and otherAedes-borne viruses. Here we report the entomological results from phased, large-scale releases ofWolbachiainfectedAe.aegyptimosquitoes throughout three contiguous cities located in the Aburrá Valley, Colombia.Methodology/principal findingsLocalwMelWolbachia-infectedAe.aegyptimosquitoes were generated and then released in an initial release pilot area in 2015–2016, which resulted in the establishment ofWolbachiain the local mosquito populations. Subsequent large-scale releases, mainly involving vehicle-based releases of adult mosquitoes along publicly accessible roads and streets, were undertaken across 29 comunas throughout Bello, Medellín and Itagüí Colombia between 2017–2022. In 9 comunas these were supplemented by egg releases that were undertaken by staff or community members. By the most recent monitoring,Wolbachiawas found to be stable and established at consistent levels in local mosquito populations (>60% prevalence) in the majority (67%) of areas.ConclusionThese results, from the largest contiguous releases ofwMelWolbachiamosquitoes to date, highlight the operational feasibility of implementing the method in large urban settings. Based on results from previous studies, we expect thatWolbachiaestablishment will be sustained long term. Ongoing monitoring will confirmWolbachiapersistence in local mosquito populations and track its establishment in the remaining areas.