When infected with Wolbachia, the mosquitoes are much less likely to transmit diseases such as dengue and Zika, because the bacteria compete with these viruses. The insects also pass the bacteria on to their offspring. Researchers hope that the modified mosquitoes will interbreed with the wild population wherever they are released, and that the number of mosquitoes with Wolbachia will eventually surpass that of mosquitoes without it.
When the scientists compared the incidence of dengue in fully treated areas with that in the same regions in the ten years before the intervention, they found that it had dropped by 95% in Bello and Medellín and by 97% in Itagüí. Since the project started, there hasn’t been a large outbreak of dengue in the region. “They’ve had six years now with a sustained suppression of dengue,” says Anders. “We’re starting to see the real-world effect of Wolbachia.”
The [World Mosquito Program] has conducted one [RCT] in Yogyakarta, Indonesia, in which mosquitoes were released in some areas of a city and the incidence of dengue was compared with that in areas that did not receive the insects. The results suggested that the technology could reduce the incidence of dengue by 77%. The organization is now conducting a similar one in Belo Horizonte, Brazil.
Despite the positive results, Wolbachia mosquitoes have not yet been officially endorsed by the World Health Organization (WHO). The technology awaits an evaluation by the WHO’s Vector Control Advisory Group.
World Mosquito Program: https://www.worldmosquitoprogram.org/en/work/wolbachia-method/how-it-works