Bacteria-carrying mosquitoes cut dengue by 77 percent

In Yogyakarta, Indonesia, researchers released mosquitoes carrying Wolbachia, a bacterium that blocks the dengue virus from replicating inside them. The insects bred with wild mosquitoes, spreading the bacterium through the local population without pesticides or genetic modification.

Researchers at Monash University and Gadjah Mada University ran a cluster-randomized trial across Yogyakarta, a city of about 400,000 people, assigning 24 neighborhoods to receive Wolbachia mosquitoes or none. Over 27 months, areas with the treated mosquitoes saw about 77 percent fewer symptomatic dengue cases than untreated areas.

The result held up enough that releases have since expanded to other Indonesian cities, and the method now runs in Brazil, Colombia and Vietnam as well as Australia, where it was first deployed. The trial covered one city over roughly two years, and researchers are still tracking whether protection holds as the bacterium spreads and as mosquito populations shift over time.

One bacterium, 77 percent fewer cases.