“Officials say that nearly all the mosquitoes in Niterói now carry Wolbachia. As a result, the World Mosquito Program, Fiocruz, and local health authorities documented a roughly 90% drop in what had been several thousand cases of dengue annually when comparing the 10 years prior to Wolbito introduction to the five years afterward.

In contrast, just across the bridge, in neighboring Rio de Janeiro where the modified mosquitoes have not yet been introduced, dengue levels have remained reasonably high during the same period.

The levels of two other mosquito-borne viruses in Niterói — chikungunya and Zika — also fell by over 96% and 99%, respectively, when comparing the roughly five years before and after Wolbito introduction. Case counts dropped from the thousands to a mere handful.”

From NPR.