Introducing Mosquitos Infected with Bacterium Reduced Dengue Fever Cases By 75%

Last year nearly 400 million people experienced Dengue fever, according to All Things Considered. (Just Brazil alone had more than 2 million cases.) But The World Mosquito Project is trying an interesting solution: Scientists are cultivating and releasing mosquitoes, except these mosquitoes are special: They’ve been infected with a bacterium called Wolbachia. Wolbachia occurs naturally in many insects, but not normally in Aedes aegypti mosquitoes, which spread dengue. It has to be introduced into the mosquitoes in the lab. But then the bacterium is passed down to future generations. The bacterium appears to block Aedes aegypti from transmitting arboviruses, which include dengue as well as chikungunya, yellow fever and Zika… “In Indonesia, we’ve [released Wolbachia-infected mosquitoes in] a community of 50,000 people and compared it to a community that was left without Wolbachia,” says Cameron Simmons, director of the impact assessment team for the World Mosquito Program. “We’ve seen a 75% reduction [of dengue cases] over the last 2 1/2 years in the Wolbachia-treated community….” The problem in the real world is that other people and other mosquitoes keep migrating into the areas being treated, messing up the experiments. But from a theoretical perspective Simmons sees Wolbachia as potentially a way to wipe out dengue entirely. “If you had a big island,” he proposes, “[and] you stop people from moving in and out of that island, and you put Wolbachia across all the mosquitoes on that island, the science suggests that you’ll eliminate dengue in that location.” Some countries are trying to do just that. Australia started using Wolbachia-infected mosquitoes nearly a decade ago to control outbreaks of imported dengue in the state of Queensland. This year the government of Malaysia launched a campaign called “Wolbachia Malaysia” to attack dengue.