The introduction of the Wolbachia bacterium into Aedes aegypti mosquito populations represents a promising biocontrol strategy aimed at reducing the transmission of arboviruses. This approach involves the mass release of Wolbachia-infected mosquitoes to establish the bacterium in local mosquito populations. Our Wolbachia method has demonstrated significant long-term durability and sustained public health benefits, even during periods of exceptionally high dengue transmission.

This publication presents the first assessment of long-term outcomes following city-wide Wolbachia deployment in Niterói, Brazil, demonstrating sustained protection against dengue during the unprecedented 2024 dengue epidemic surge across the Americas.

Executive Summary:

This study evaluated the long-term entomological and epidemiological effectiveness of city-wide deployment of wMel-strain Wolbachia-infected Aedes aegypti in Niterói, a Brazilian city of half a million people. Following phased releases across three-quarters of the urban population in 2017-2019, releases were expanded to remaining populated areas in 2023, achieving complete city-wide coverage. The key findings include:

• wMel was durably established at ≥95% prevalence in Ae. aegypti populations throughout Niterói four years post-release, and up to seven years in the earliest release sites, with no re-releases required.
• Notified dengue case incidence in Niterói was 89% lower following Wolbachia releases compared to the 10-year pre-intervention period of 2007-2016.
• During the record-breaking 2024 dengue epidemic in Brazil, dengue incidence in Niterói was 374 per 100,000 population, substantially lower than overall in Rio de Janeiro state (1,884 per 100,000) and nationwide in Brazil (3,157 per 100,000).
• City-wide Wolbachia coverage provided sustained population-level reduction in dengue incidence throughout the five years post-intervention, including during the 2024 epidemic surge.
• The study estimated that Wolbachia prevented at least three-quarters of the dengue case burden that may otherwise have been expected in Niterói in 2024, corresponding to between 5,242 to 11,660 cases averted.

The study concluded that our Wolbachia method demonstrates robust long-term durability and sustained public health benefits, providing evidence for the effectiveness of this intervention even during periods of very high dengue transmission intensity.

Further Information:

• Authors: Katherine L. Anders, Gabriel Sylvestre Ribeiro, Renato da Silva Lopes, Pilar Amadeu, and colleagues from the World Mosquito Program and partner institutions.
• Journal: Tropical Medicine and Infectious Disease (2025) 10:237.
• DOI: https://doi.org/10.3390/tropicalmed10090237
• Funding: This research was supported by the Brazilian Ministry of Health (DECIT/SVS, grant 25380.000814/2016-13).