Fighting Mosquitoes With Mosquitoes: Ten Years On, Project Wolbachia Reaches Half of Singapore’s Homes
Ten years ago, the idea sounded almost backwards: to fight a mosquito-borne disease, release more mosquitoes. In 2016 Singapore tested the concept at three sites. On October 31, at a carnival at Our Tampines Hub marking the programme’s tenth anniversary, Senior Minister of State for Sustainability and the Environment Janil Puthucheary announced that Project Wolbachia now covers more than 840,000 households, or 53% of all homes in the country, including most of the areas at risk of large dengue outbreaks. The latest expansion came with a launch in Ang Mo Kio on October 6.
How the trick works
The programme breeds male Aedes aegypti mosquitoes carrying Wolbachia, a naturally occurring bacterium. Male mosquitoes do not bite. When they mate with wild females, the resulting eggs do not hatch, so the local population shrinks over time. No insecticide clouds, no genetic editing, just a carefully managed mismatch.
The evidence has grown steadily. Research published in the New England Journal of Medicine in February found Aedes aegypti populations fell by 80 to 90% in covered areas, while residents’ dengue risk dropped by more than 70%. Nationally, reported cases fell to a seven-year low of 4,036 in 2025, a 70% drop from 13,651 the year before.
From suspicion to support
The scheme did not win hearts overnight. Lee Tee Loon, who chairs the Citizens’ Consultative Committee in Braddell Heights, one of the original 2016 sites, recalls anxiety among residents when the releases began. Over time, he says, people came to see it as something good for the community. That shift is perhaps the project’s quietest achievement: persuading a dense city to welcome swarms of insects in the name of public health.
The anniversary also had a lighter side. The National Environment Agency (NEA) launched a children’s book, Kai’s Tiny Adventure with Wozzie, starring the project’s mascot, which will be available in public libraries to explain the science to young readers.
Not a silver bullet
Officials were careful not to declare victory. Janil stressed that dengue prevention remains a shared responsibility and that Wolbachia targets only Aedes aegypti, while Singapore is home to many other mosquito species, some of which can also carry dengue, Zika and chikungunya. Removing stagnant water at home remains the first line of defence.
The numbers explain the caution. Singapore recorded 2,564 dengue cases in the first three quarters of 2026, down 25% from the same period in 2025. But cases in the third quarter jumped 79.7% from the previous quarter, to 1,384, and one death in that period brought this year’s toll to three. The DENV-3 serotype made up 45.9% of cases by the end of September, overtaking DENV-2, and a change in the dominant strain is typically followed by a rise in infections because fewer people are immune to it. NEA also points to the peak season from May to October and the ongoing El Nino, whose hotter, drier weather speeds up the mosquito life cycle.
Raman Velayudhan, deputy chair of NEA’s dengue expert advisory panel and a former WHO official, noted that global case numbers have fallen, but warned that El Nino and changing weather could push them up again in 2027, including in Singapore. Asked about further expansion, NEA said it would assess the situation before deciding.
A decade in, Project Wolbachia offers a template other tropical cities are watching: patient science, steady public persuasion and honest limits. The mosquitoes are fewer. The work is not finished.