MARY LOUISE KELLY, HOST:
There are factories in Brazil where one of the most reviled creatures known to humans is being bred intentionally by the millions - mosquitoes. Now, the folks who work in these high-tech factories will tell you these are not your grandmother's mosquitoes. They are actually designed to protect people from the diseases that mosquitoes carry. It's a major investment for Brazil, one that other countries, especially in the Americas, are keeping an eye on. Reporter Ari Daniel has our story.
(SOUNDBITE OF LIQUID FLOWING)
ARI DANIEL, BYLINE: I'm in eastern Rio de Janeiro, inside what's basically a bug-making factory. A large room is filled with netted cages teeming with mosquitoes.
(SOUNDBITE OF MECHANISM CLANKING)
DANIEL: Where's the blood? Can I see the blood?
CATIA CABRAL: Oh...
DANIEL: Catia Cabral supervises the facility. She points to a small bag of blood in each cage where the insects can feast.
Wow. Amazing. These are the adults that will lay your eggs?
CABRAL: (Non-English language spoken). Yes.
DANIEL: Once those eggs hatch, they end up here...
(Non-English language spoken), the larva room.
(SOUNDBITE OF WATER POURING)
DANIEL: ...Where untold numbers of tiny larvae wriggle in bins filled with water. These mosquitoes, they're special. They've been engineered to stop the spread of dengue, a disease that's wrought havoc on millions of people in Brazil and elsewhere. The trick is that inside these mosquitoes are microbial stowaways, something called Wolbachia.
DIOGO CHALEGRE: So Wolbachia, it's a bacteria.
DANIEL: A bacteria that's naturally present in roughly half of all insect species, including, says Diogo Chalegre, some mosquitoes. Chalegre's a trained biologist who worked with the nonprofit World Mosquito Program until recently. And he says this bacteria and the virus that causes dengue, for some reason, they can't live together inside the mosquito.
CHALEGRE: It's like there is a competition between Wolbachia and the virus. So once Wolbachia is inside these mosquitoes, the virus cannot replicate.
DANIEL: And if dengue can't replicate, then the mosquito can no longer transmit the virus to people. So Chalegre's colleagues wondered, could they use Wolbachia to stop dengue from spreading?
CHALEGRE: That's it. That's the theory.
DANIEL: The only problem was the mosquitoes they needed to target don't naturally carry Wolbachia, so they had to introduce the bacteria into the bug by inserting Wolbachia into the mosquito eggs using a very fine glass needle - a process that ended up taking five years. And the resulting Wolbitos...
CHALEGRE: Wolbachia plus mosquito equals Wolbito (laughter).
DANIEL: ...Pass the bacteria on to their babies because once the bacteria is present in the mosquito population, it stays put.
CHALEGRE: So we expect to have a drop in the cases of dengue.
DANIEL: Such a drop would be huge, since severe dengue, when left untreated, is rough.
OTAVIO HAGUIUDA JR: It's terrible. It hurts like our bones are being broken.
DANIEL: Otavio Haguiuda Jr. is a family physician at a community clinic in Joinville, a city in the south. He's seen dengue crises up close, where the disease damages the blood vessels so they become leaky like a sieve, leading to internal bleeding.
HAGUIUDA: And yes, I had people who died with me of dengue.
DANIEL: Brazil accounts for the bulk of dengue across the Americas. Already this year, there have been over 3 million cases here. And when an outbreak happens, Haguiuda says it can devastate an already strapped health system.
HAGUIUDA: Chaos, total chaos.
DANIEL: Brazil does have dengue vaccines, though the immunization efforts have struggled a bit. But now there's been more than a decade of field trials using the Wolbachia mosquitoes, and they've demonstrated the approach works and it's safe. A study published in November, for example, showed that in a city near Rio, cases of dengue dropped by about 90% after Wolbitos were released.
JOHANNA FRASER: Evidence to date suggests it is going to be a very effective solution.
DANIEL: Even if it's a somewhat limited one, says Johanna Fraser. She's a virologist at the Burnet Institute in Melbourne.
FRASER: To do it to the stage of eliminating dengue will be really difficult simply because it's such a big place.
DANIEL: Still, given Wolbachia's successful track record, Brazil is committed to adding these modified mosquitoes to their arsenal in the fight against dengue.
(SOUNDBITE OF ARCHIVED RECORDING)
ALEXANDRE PADILHA: (Speaking Portuguese).
DANIEL: Alexandre Padilha, the minister of health, took to social media recently to explain the country's ambitious goal...
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PADILHA: (Speaking Portuguese).
DANIEL: ...To protect 140 million Brazilians against the dengue mosquito, he says. It's a 10-year plan in partnership with the World Mosquito Program, and the work, it's already begun.
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DANIEL: In the southern city of Joinville, I don a white jumpsuit to protect me from the mosquitoes and join a team of local health workers. They're about to flood the surrounding community with Wolbitos. Fabiane Rudnick helps run the show here.
FABIANE RUDNICK: With my work, I can do something good for the community and for my family.
(SOUNDBITE OF CAR DOORS CLOSING)
DANIEL: But enough chitchat.
RUDNICK: It's time to go.
DANIEL: OK.
(SOUNDBITE OF GRAVEL CRUNCHING)
DANIEL: I ride shotgun in a white Chevy stocked with dozens of tubes of mosquitoes, and we head to a sparse residential neighborhood on the outskirts of the city.
So we're releasing from the car, slowing down to the first site.
One by one, a technician holds a tube outside the window, and rather than killing mosquitoes, like most other control efforts, he opens each tube and lets a couple hundred of the factory models lift off.
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DANIEL: No. 2.
(SOUNDBITE OF TAPPING)
DANIEL: Just recently, a massive new mosquito factory opened about 80 miles from here. The goal is to produce some 5 billion of these mosquitoes in the first year. The car inches along.
(SOUNDBITE OF TAPPING)
DANIEL: No. 11.
And another puff of mosquitoes fills the air with the hope of a different future carried on tiny, albeit annoying, wings.
For NPR News, I'm Ari Daniel, Joinville, Brazil. Transcript provided by NPR, Copyright NPR.
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