ARI SHAPIRO, HOST:
Infecting mosquitoes with a naturally occurring bacteria appears to block them from spreading several major tropical diseases, including dengue and Zika. The relatively new approach comes at a time when dengue cases have been rising globally. They're expected to increase even more as climate change expands the range of the dengue mosquito. NPR's Jason Beaubien reports.
JASON BEAUBIEN, BYLINE: Cameron Simmons, with the nonprofit World Mosquito Program, is far more familiar with dengue then he'd like to be.
CAMERON SIMMONS: I've had dengue. My family's had dengue. It's a miserable, miserable experience and not one I - you know, I'd ever want to repeat or have anyone else experience.
BEAUBIEN: Unfortunately, last year, according to the WHO, nearly 400 million people experienced the viral disease that's often called breakbone fever. And in tropical places where dengue is rampant, annual outbreaks are a huge burden on local health clinics. Simmons and his colleagues want to change that.
SIMMONS: You know, throughout Southeast Asia, dengue's guaranteed every rainy season through most of Southeast Asia. And so communities know and, indeed, public health colleagues in those communities know that what they do at the moment doesn't work.
BEAUBIEN: So instead of trying the old method of attempting to trap and kill all the Aedes aegypti mosquitoes, the World Mosquito Program is doing the opposite. They're cultivating and releasing mosquitoes, except theirs have been infected with a bacteria called Wolbachia. The bacteria appears to block the mosquitoes' ability to transmit arboviruses, which include dengue, Zika, yellow fever and chikungunya. Simmons is presenting results this week at the American Society of Tropical Medicine and Hygiene of several trials his group is doing around the world. And he says they're finding the technique effective at reducing dengue.
SIMMONS: In Indonesia, where we've treated a community of 50,000 people, compared it to a community that was a similar community that was left untreated - without Wolbachia - we've seen a 75% reduction over the last 2 1/2 years in the Wolbachia-treated community.
BEAUBIEN: He says in laboratory studies, they've been able to use this bacteria to completely stop dengue transmission, and some countries are trying to do just that. This year, the government of Malaysia launched a campaign called Wolbachia Malaysia to attack dengue. The campaign isn't affiliated with Simmons' group, the World Mosquito Program. But conceptually, it's trying to do the same thing - make the mosquitoes incapable of spreading viral diseases. This year, there's been a record number of dengue cases in the Americas, with Brazil reporting more than 2 million cases since January. Luciano Moreira is the lead scientist for the World Mosquito Program in the country. He says the dengue mosquitos are everywhere in Brazil.
LUCIANO MOREIRA: Because they can live even in high-rise buildings and, like, in vases and, like, plant pots and everywhere, even a very small amount of water, they'll be there. And they can survive.
BEAUBIEN: In 2018, there actually wasn't much dengue in the areas where they released their mosquitoes, so Moreira wasn't able to tell how much of an impact they had on dengue. But they did see a 70% drop in cases of chikungunya, compared to a neighboring area without the Wolbachia-infected mozzies (ph).
Jason Beaubien, NPR News.
NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.