DAVID GREENE, HOST:
Let's get an inside look at what the fight against the Zika virus might look like if, as some predict, it arrives in the mainland United States this summer. Harris County, Texas, which encompasses Houston, has one of the largest mosquito control operations in the U.S. Scientists work year-round testing mosquitoes for viral activity.
Carrie Feibel from Houston Public Radio recently slapped on the repellent and tagged along.
CARRIE FEIBEL, BYLINE: You can't see them. But on any given weekday, hundreds of mosquito traps are scattered across Harris County. Christy Roberts, an insect scientist for the county, steers a pickup truck through winding suburban streets. She retrieves trap after trap tucked under manhole covers and under hedges and trees.
Along the side of a ranch house, Roberts holds up a net filled with flickering grey wings.
CHRISTY ROBERTS: Lots of females. Some of them are blood-fed. And we had males in there, too.
FEIBEL: This trap is clamped over a plastic tub. The stagnant, smelly water is irresistible to female mosquitoes.
ROBERTS: The female will fly over the water. And they'll land on top of the water to lay their eggs. And as they're floating on top of the water, the fan will suck them up into the net.
FEIBEL: It's the female mosquitoes that bite because they need blood to reproduce. As the truck heads back to the lab, nets full of mosquitoes swing from hooks in the back seat.
ROBERTS: So we hang the nets so that the mosquitos continue to fly. They won't rub their scales off, which is what we need to identify them. It also helps keep them alive until we can freeze them.
FEIBEL: Traps stay out overnight, about 12 hours. In the mornings, technicians fan across the county to retrieve them. In the afternoons, they set out fresh traps in different locations. Roberts sits down at a lab bench and picks through dead mosquitoes with tweezers. She's looking for females of a certain species.
ROBERTS: I am sorting for Culex quinquefasciatus, which is our primary vector for West Nile. And I'm just placing them directly into the vile.
FEIBEL: They're looking five viruses - West Nile, St. Louis encephalitis, Dengue, Chikungunya and now Zika. West Nile is the big one. They usually find several hundred infected mosquitoes a year. But so far, there's been no Zika. Dr. Mustapha Debboun is the director of mosquito control. He says the bad news is that Harris County is home to 56 different species of mosquitoes.
But the good news is you only have to worry about three.
MUSTAPHA DEBBOUN: We have this Aedes aegypti and the Aedes albopictus, which is also the Asian tiger mosquito, and the Culex mosquito. And thank God, we're only dealing with three.
FEIBEL: To two Aedes species carry Zika. After the sorting, other scientists grind up the mosquitos to look for the viruses. Still, others breed mosquitoes for experiments or field test new devices for killing them. The division spends at least $4 million a year - half of that for the trapping and lab work.
Debboun says most people don't know about the science being done behind the scenes. They assume that mosquito control just means spraying chemicals. But Debboun says they only spray where it makes sense.
DEBBOUN: We go hit the areas where we know that mosquitos have this disease in them. So we don't just go randomly and just spray and waste - not only waste the pesticide, but also put a pesticide in the environment when you don't need to. So we do it scientifically, data-driven.
FEIBEL: Debboun says he feels ready for Zika. He has spent $300,000 on new lab equipment so the scientists can do more precise tests for Zika in-house. He's also planning to ask the county for more than 70 new traps. Those traps, which cost $300 a piece, are especially attractive to the mosquitoes that carry Zika. For NPR News, I'm Carrie Feibel in Houston.
GREENE: And Carrie's story is part of a reporting partnership with NPR, Houston Public Media and Kaiser Health News.
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