Infected mosquitoes fighting dengue fever with 70 percent effectiveness: a two-year large-scale trial by Singapore's National Environment Agency (NEA), whose results were published in February 2024 in The Lancet Microbe, shows measurable results. The method uses the bacterium Wolbachia, which blocks dengue viruses from replicating inside mosquitoes, without insecticides or genetic modification. By the end of 2026, around 800,000 Singaporean households, half of all in the country, are to be covered by the program.
How Wolbachia Works
Wolbachia is not a laboratory product but a naturally occurring bacterium. It lives in about 60 percent of all insect species, but not in the Asian tiger mosquito (Aedes aegypti), the main carrier of dengue fever. When researchers infect Aedes females in the lab with Wolbachia and release them, the bacterium blocks dengue virus replication inside the mosquito's body. An infected mosquito can still bite, but can no longer transmit the virus.
Singapore's strategy is precise. Rather than infected females, only infected males are released, which do not bite. These mate with wild females in the surrounding area. Because Wolbachia affects egg development, offspring from such pairings do not survive. The wild mosquito population shrinks generation by generation, without toxins and without permanent alteration of the gene pool.
What the Study Shows
The NEA conducted a cluster-randomized controlled trial between 2022 and 2024 in several Singapore neighborhoods, involving over 700,000 residents. The results, published in The Lancet Microbe and The Lancet Planetary Health:
In neighborhoods with more than six months of active releases, the dengue positivity rate was 6 percent. In control areas without releases it was 21 percent, a reduction of 70 percent. The wild mosquito population in treated areas fell from an average of 0.18 to 0.041 mosquitoes per trap, a decline of 77 percent.
Dengue is not a marginal disease. The WHO estimates that up to 400 million people are infected globally each year. Over 100 countries are considered endemic, mostly in tropical and subtropical regions. Effective vaccines exist only in limited form and with contraindications. Biological control methods like Wolbachia are therefore considered one of the most promising alternatives.
Comparable Results From Other Dengue Strategies
Singapore's Wolbachia approach competes and complements two other methods that have produced solid data.
The World Mosquito Program (WMP) takes a different variant: instead of sterile males, infected females are released to establish Wolbachia-carrying populations in the wild. In Yogyakarta, Indonesia, a 2021 study published in the New England Journal of Medicine showed a 77 percent dengue reduction in treated neighborhoods compared with control areas. The WMP model aims for lasting population change; Singapore's model targets continuous suppression through regular releases.
In parallel, the Butantan Institute in Brazil developed a dengue vaccine whose five-year results were published in early 2026: among vaccinated participants, there were zero hospitalizations. The vaccine targets people not previously exposed to dengue, which limits its use to certain age groups and regions.
Both comparisons show the same pattern: biological control methods achieve dengue reduction rates that insecticides alone cannot match.
Who Is Moving Next
The NEA plans expansion to all 24 of Singapore's community centers. By end of 2026, around 800,000 households are to be covered, according to a January 2026 announcement.
Internationally, countries with high dengue burdens are watching Singapore's model closely. Sri Lanka has announced a pilot phase. Malaysia and Thailand are running their own small-scale Wolbachia trials. The key question is whether the approach, which has so far worked best in densely populated city-states with controllable borders, will also scale in megacities with open urban boundaries such as Jakarta or Mumbai. Singapore's dataset is the most robust evidence yet that biological mosquito control works at city scale with measurable effect.