Singapore's Wolbachia programme now covers 53% of homes: over 840,000 households, dengue risk sharply down but Q3 cases rebounded

Singapore's dengue-control programme passed a milestone on October 31. The National Environment Agency (NEA) announced at the Project Wolbachia 10th anniversary event at Our Tampines Hub that the programme now covers more than 840,000 households — 53 per cent of all homes in Singapore — after its expansion into Ang Mo Kio on October 6, covering most areas identified as at risk of large dengue outbreaks. Senior Minister of State for Sustainability and the Environment Janil Puthucheary announced the figure at the event.

Fighting mosquitoes with mosquitoes: males that do not bite

Project Wolbachia works by regularly releasing laboratory-reared male Aedes aegypti mosquitoes carrying the naturally occurring Wolbachia bacterium. The males do not bite; when they mate with wild females, the eggs laid do not hatch, so the wild mosquito population gradually falls. The NEA stresses this is not a new species being introduced — the released mosquitoes are the same Aedes aegypti already found in the environment, carrying a bacterium naturally present in more than 60 per cent of insect species.

The results: mosquito numbers down 80–90%, cases at a seven-year low

Research published in The New England Journal of Medicine in February showed that in release areas, Aedes aegypti populations fell by 80 to 90 per cent and residents' dengue risk dropped by more than 70 per cent. National figures improved in step: NEA data put reported dengue cases in 2025 at 4,036, a seven-year low, down about 70 per cent from 13,651 in 2024.

The warning: Q3 2026 cases surged as DENV-3 took over

The latest numbers also carry a warning. The first three quarters of 2026 saw 2,564 cases, 25 per cent fewer than the same period last year, but the third quarter alone recorded 1,384 infections, up 79.7 per cent on the second quarter. By the end of September, the DENV-3 serotype accounted for 45.9 per cent of cases, displacing DENV-2 as dominant; NEA Environmental Health Institute officials explain that when the dominant serotype switches, lower population immunity typically triggers a spike. The authorities and experts therefore repeat the same reminder: the programme suppresses only one mosquito vector, and clearing stagnant water remains the cornerstone of dengue prevention.