Mosquitoes armed with bacteria beat back dengue virus
NATIONAL HARBOR, MARYLAND—In a handful of cities around the world, mosquitoes have been armed with a microscopic weapon against disease. The bacterium Wolbachia pipientis blocks the insects’ ability to spread fearsome viruses such as dengue, Zika, and chikungunya. Since 2011, researchers have been injecting Wolbachia into the eggs of Aedes aegypti mosquitoes and releasing the hatched insects, which spread this protection to their offspring. But the field has been waiting for evidence that this approach actually reduces disease in people.
Signs that it does came this week in preliminary results from several trials in tropical areas burdened with mosquito-borne viruses such as dengue. In some release areas, studies conducted by the nonprofit World Mosquito Program (WMP) found as much as a 76% reduction in the rate of dengue, which causes fever and severe joint pain and has no specific treatment.
Wolbachia naturally inhabits many insects, though not A. aegypti. In mosquito cells, the bacterium can prevent viruses such as dengue from replicating—and thus from spilling into a new host when a mosquito bites. Proponents say the approach could complement traditional methods such as insecticide sprays, which often fail to control disease. And because the bacterium spreads on its own, it could be more cost effective than population-reducing approaches such as genetic engineering, some of which require ongoing releases.