Description
Introduction
Previous studies have shown that Ae.aegypti mosquitos infected with Wolbachia bacterium cannot transmit arboviruses to humans and that by introducing Wolbachia bacterium into Ae.aegypti mosquitos populations it is possible to reduce dengue rates in an area by up to 90%. Wolbachia bacterium inhibits the uptake of Arboviruses through three mechanisms: 1) Wolbachia strengthens the mosquito's immune system 2) Wolbachia inhibits anchors for Arbovirus adhesion in the mosquito salivary glands 3) Wolbachia bacterium consumes the same lipid resources Arboviruses needs for replication. The World Mosquito Program has developed a method of inserting Wolbachia bacterium into Ae.aegypti mosquitos which can be passed to their offspring, thereby preventing the transmission of arboviruses in large populations. Médecins Sans Frontières (MSF) is currently introducing Ae.aegypti mosquitos containing Wolbachia into the Honduran community of El Manchen. However, for Wolbachia to be self-sustaining in the Ae.aegypti population, the prevalence of Wolbachia must be above 80% and it is unknown if this is feasible in El Manchen.
Objective
To demonstrate the feasibility of introducing Wolbachia bacterium into the Ae.aegypti mosquito population of the Honduran district of El Manchen.
Methodology
Ae.aegypti ovum capsules inoculated with Wolbachia were imported from World Mosquito Program facilities in Colombia. Capsule contained approximately 150-250 ovum each and were transported to MSF facilities in Honduras at 15-18°C. Mosquitos were hatched from the capsules by placing them in 500 ml of water and incubated at 27-29°C for 7-9 days. Once mosquitos reached their adult phase, releases of mosquitos into the community was carried out across predetermined GPS points, with each release being approximately 50 meters apart. MSF began releasing mosquitos on August 26th, 2023 and is expected to continue until releasing mosquitos until February 2024. Adult mosquitos will be released at over 1200 points, while ovum are dispersed in containers by community volunteers through approximately 100 community releases per week. In October 2023, MSF began weekly monitoring of the taxonomic prevalence of Ae.aegypti mosquitoes compared to the prevalence of other mosquito species present in El Manchen. Additionally, the prevalence of Wolbachia bacterium in the Ae.aegypti mosquito population is assessed weekly at Universidad Nacional Autónoma de Honduras laboratories through the detection of Wolbachia surface proteins using polymerase chain reaction.
Results
A baseline assessment of the taxonomic distribution of mosquito species demonstrated that 70% of mosquitos were Ae.aegypti, 26% Culex spp, 4% Ae. albopictus. As of November 30th, 2023 over 2,500,000 adult mosquitoes have been released and more than 300 ovum containers have been distributed. A significantly increasing trend in the prevalence of Ae.aegypti mosquitos containing Wolbachia was observed by November 30th, with weekly percentages being 16.3%, 24%, 28.16%, and 30.52%.
Conclusions
Our preliminary results demonstrate an increasing trend in the prevalence of Ae.aegypti mosquitos containing Wolbachia. This suggests that the integration of Wolbachia into the mosquito population of El Manchen could be feasible. While this project is projected to continue for 3 years, early data suggests the project is on track to reach the target goal of an 80% prevalence of Ae.aegypti mosquitos containing Wolbachia.
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