Effectiveness of Project Wolbachia Phase 5 to Curb Dengue

Mr Gerald Giam Yean Song asked the Minister for Sustainability and the Environment (a) with regard to Project Wolbachia Phase 5 to curb dengue, whether there are (i) any indicators used to ascertain its effectiveness beyond the number of dengue cases and the size of the mosquito population and (ii) any unintended consequences and trade-offs discovered; and (b) whether there are plans for additional phases of Project Wolbachia in (i) housing estates and (ii) industrial estates.

The National Environment Agency (NEA)'s Project Wolbachia field studies in the initial four sites, including the expansions in 2020, had achieved more than 90% reduction of the local Aedes aegypti mosquito population. Data from 2019 to 2022 also indicates that residents living in areas with at least one year of releases were up to 77% less likely to be infected with dengue. In addition to monitoring the impact of Project Wolbachia on the Aedes aegypti mosquito population and dengue cases, community surveys revealed strong support for Project Wolbachia, with 96% of residents being accepting of releases in their neighbourhoods.

Following positive results, NEA will expand Project Wolbachia to five additional residential areas in the first quarter of 2024, bringing the coverage of male Wolbachia-Aedes releases from 26% to 35% of all households in Singapore. NEA does not have any plans to expand Project Wolbachia to industrial estates at the moment and will focus on residential estates where dengue clusters are most prevalent.

NEA has not observed any negative impact from Project Wolbachia from its trials. Prior to carrying out the trials, NEA had carried out risk assessments and deemed the technology safe, posing no risk to human health and an insignificant risk to the ecology, including to other mosquito species. NEA's observations are also consistent with other research findings from around the world. We will continue to conduct field studies to further understand the environmental factors affecting the efficacy of Project Wolbachia, improve our deployment strategy and enhance its cost-effectiveness.