São José do Rio Preto releases Wolbachia‑infected mosquitoes to fight dengue

São José do Rio Preto, a city in Brazil heavily affected by dengue, Zika and chikungunya, will begin releasing Aedes aegypti mosquitoes inoculated with the natural Wolbachia bacterium. The program, carried out with the Fundação Oswaldo Cruz (Fiocruz), selected ten priority neighborhoods after mapping recent case concentrations. Field work started in May, and the first street releases are scheduled for September‑October 2026, with weekly releases planned over 26 weeks.

Wolbachia, found in many insects, blocks virus replication in the mosquito without any genetic modification. Fiocruz officials say the technique has already been used in 15 countries and 16 Brazilian cities. The city recorded more than 4,000 dengue cases in the first half of 2026, following its worst epidemic in 2025 (53,000 cases and 41 deaths). Local health teams will accompany the releases with community education and outreach to inform residents about the safety and purpose of the “Wolbitos.”