Brazil Expands Wolbachia Mosquito Program As Dengue Cases Rise Across Warmer Regions

Brazilian scientists are racing to expand the use of mosquitoes infected with a bacteria that blocks dengue transmission as climate change accelerates the spread of the disease across the country. Researchers say rising temperatures are allowing dengue-carrying mosquitoes to thrive in regions of Brazil that were previously too cold for the virus, increasing pressure on public health systems already struggling with repeated outbreaks.

At the center of the effort is a large mosquito-breeding facility in the southern city of Curitiba, where scientists produce millions of specially modified mosquitoes known locally as “wolbitos.” The insects are infected with the Wolbachia bacterium, which prevents the transmission of dengue as well as other mosquito-borne viruses including Zika and chikungunya. The project is led in part by Brazilian entomologist Luciano Moreira, who helped develop the technique in Australia in 2008 and has since become one of the leading global figures in dengue research.

The Curitiba bio-factory, inaugurated in 2025, is currently the world’s largest facility dedicated to breeding Wolbachia-infected mosquitoes. Inside temperature-controlled rooms, workers maintain ideal breeding conditions for Aedes aegypti mosquitoes, which are fed a mixture of warm horse blood and sugar water. The factory can produce up to 100 million eggs per week, with capsules containing the eggs shipped to urban areas across Brazil. Once released, the infected mosquitoes gradually reproduce and outnumber ordinary mosquitoes capable of spreading dengue.

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Despite the scientific success of the program, researchers warn that implementation has not kept pace with the growing threat posed by dengue. Brazil recorded a severe outbreak in 2024 that killed more than 6,000 people, while millions remain at risk across the country. Moreira said climate change has contributed significantly to the spread of dengue into southern regions where the disease was previously uncommon. Trials conducted in the cities of Niteroi and Campo Grande showed dengue cases fell by 89 percent and 63 percent respectively after the release of Wolbachia-infected mosquitoes.

Public health experts, however, say expanding the project nationwide remains a major challenge. Ludimila Raupp, a professor at the Pontifical Catholic University of Rio, said implementation efforts have faced logistical difficulties, coordination failures and operational setbacks in some regions. In Rio de Janeiro, heavy use of larvicides by local health teams reportedly harmed the modified mosquitoes, while organized crime-related violence in some favelas disrupted release operations.

Brazilian Health Minister Alexandre Padilha acknowledged that scaling up the program involves significant technical, logistical and financial hurdles, but confirmed the Wolbachia method will be expanded to 54 additional cities this year, bringing the total number of participating municipalities to 70. Researchers stress the strategy is not a standalone solution but part of a broader fight against dengue that also includes vaccination campaigns. Brazil recently developed the world’s first single-dose dengue vaccine, while India is conducting final-stage trials for another vaccine candidate aimed at curbing the spread of the disease globally.

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