Sterile Wolbachia-Infected Mosquitoes Reduce Dengue Risk by Over 70 percent: NEJM
Researchers have found in a new study that releasing sterile Wolbachia-infected male Aedes aegypti mosquitoes significantly reduced mosquito populations and lowered dengue infection risk. In treated areas, only 6% of residents tested positive for dengue after 6 months or more, compared with 21% in untreated areas. The intervention demonstrated over 70% protective efficacy at 3 months, 6 months, and one year following implementation. The study was published in The New England Journal of Medicine by Jue T. and colleagues.
Dengue fever continues to pose a significant public health problem in tropical countries, where Aedes aegypti acts as its principal vector. If wild-type female mosquitoes mate with male infected mosquitoes with wAlbB strain of Wolbachia, incompatible cells will prevent them from giving birth, leading to reduced population size over time. The trial entails the biological control of Aedes populations through repeated releases of infected males, thereby controlling the spread of the disease. This trial was conducted to assess its effectiveness in Singapore, which is densely populated and experiences dengue fever.
The trial design is a cluster-randomized trial with test-negative controls. It comprises 15 geographic population clusters, evenly divided into two groups of 8 and 7 geographic clusters for the intervention and controls, respectively. The controls did not have any deployments of male Wolbachia-infected mosquitoes.
There were a total of 393,236 residents from the intervention clusters, compared to 331,192 residents from the control clusters. The outcome measure of interest was confirmed symptomatic dengue infection of any severity and any serotype. The effectiveness of the intervention was based on the estimation of the odds ratio for exposure to Wolbachia among confirmed dengue cases compared to test-negative controls.
Key findings
In 15 geographic clusters, 8 received Wolbachia-infected male mosquito releases, and 7 served as controls.
A total of 393,236 residents were in intervention clusters and 331,192 in control clusters.
Baseline mosquito abundance was 0.18 vs 0.19, respectively.
During the 24 months, average abundance declined to 0.041 in intervention clusters versus 0.277 in control clusters.
Dengue positivity was 6% (354 of 5722 tests) in intervention clusters compared with 21% (1519 of 7080 tests) in control clusters.
Protective efficacy ranged from 71% to 72%, corresponding to odds ratios of 0.28 to 0.29.
The use of sterile wAlbB strain of Wolbachia-infected male Aedes aegypti mosquitoes was effective in the reduction of vector populations and the risk of symptomatic dengue infection in Singapore. The efficacy of the intervention, at 71-72%, justifies the intervention as a viable and innovative approach towards the management of dengue infection.
Reference:
Lim, J. T., Chong, C.-S., Chang, C.-C., Mailepessov, D., Dickens, B., Lai, Y. L., Deng, L., Lee, C., Tan, L. Y., Chain, G., Zulkifli, M. F., Liew, J. W. K., Vasquez, K., Chau, M. L., Ng, Y., Lee, V., Wong, J. C. C., Sim, S., Tan, C. H., & Ng, L. C. (2026). Dengue suppression by male Wolbachia-infected mosquitoes. The New England Journal of Medicine, NEJMoa2503304. https://doi.org/10.1056/nejmoa2503304
