250,000 genetically modified mosquitoes are released each day in Sao Palo. They spend their lives competing, copulating, and, because they are so numerous, overwhelming the population of wild males in the pursuit of females. Because of a genetic change to their DNA, they will live only four days—and their offspring won’t ever develop past the larval stage.
The insects were developed by Oxitec, a U.K. company that calls them “Friendly Aedes” and produces them at a facility located an hour away by car. Although the insects aren’t yet commercially available, the pilot program in Piracicaba has become a test case for whether GM insects can stop disease—and, if so, whether it will be at a cost cities can afford.
The project here began in April 2014, a year after an epidemic of dengue fever that caused more than 1.5 million cases in Brazil. So far, it is working: after 10 months of testing in two small neighborhoods, the number of dengue cases among 5,600 residents fell from 133 in a year to only one.
In addition to GM mosquitoes, there are experiments using mosquitoes infected with a bacterium, Wolbachia, that seems to prevent them from spreading diseases. Research on that idea has been supported with $40 million by the Bill & Melinda Gates Foundation, which hopes it could be extensively deployed in Brazil in the coming months. A still more futuristic approach, which would use gene editing to eradicate mosquitoes, remains years from actual use.
Last August Oxitec, which has also staged releases in Panama and the Cayman Islands, was acquired for $160 million by the U.S. conglomerate Intrexon, which owns a portfolio of transgenic organisms including salmon and apple trees. Now that Brazil is fighting Zika as well as dengue—both are spread by Aedes mosquitoes, as is the chikungunya virus—interest in the technology has surged. “The moment of crisis will pass, but we’re sure that our technology is here to stay,” says Glen Slade, director of Oxitec’s Brazil operation.
SOURCES -Technology Review