STEVE INSKEEP, HOST:
We are tracking a disease that has killed tens of millions of birds.
RENEE MONTAGNE, HOST:
It's this nation's worst epidemic of avian influenza, or bird flu. It took hold in the upper Midwest.
INSKEEP: And it's left some 38 million chickens and turkeys dead. Some were killed by the flu, and others were killed to stop it from spreading.
MONTAGNE: It may, in time, affect your grocery bill. Scientists say this outbreak is spreading in a way they've never seen before. Here's Iowa Public Radio's Sarah Boden.
SARAH BODEN, BYLINE: I'm sitting in the tall grass on the banks of Jensen Marsh in southern Iowa, and everywhere I look, I see a bird. There's a bunch of red-wing blackbirds. And earlier today, there were some raptors circling overhead. And there are a lot of ducks today. Migratory waterfowl tends to stop here on their way north to summer nesting grounds.
MICHAEL OSTERHOLM: Influenza viruses have thought in the past to be transmitted by birds to birds in close contact and that it was only through that kind of transmission that we need to be concerned. Now we surely have a very dynamic situation in the Midwest. It's also a situation where we no longer can just assume this is all migratory birds.
BODEN: That's Dr. Michael Osterholm who studies infectious diseases at the University of Minnesota. This particular strain moving through the Midwest is called H5N2. It mutated from another strain of influenza that was carried by birds from Asia to North America. Any number of theories could explain the virus's rapid transmission. It could be humans carrying it or small rodents infiltrating facilities to contaminated feed and water. The virus could even be airborne. Osterholm says the poultry industry is in uncharted territories.
OSTERHOLM: The virus is doing things that we've never seen it do before. Because we don't understand that, our understanding of what we can do about it is also very limited.
BODEN: This January saw the first confirmed case in a backyard flock in Washington state. Today, there are nearly 170 confirmed outbreaks. Less than an hour's drive from a commercial egg-laying facility that was hit by the virus in early May, I meet up with Dale Raasch, an organic poultry producer. He keeps a flock of about 550 chickens, mostly for eggs. Because of avian flu, Raasch no longer allows most people on his property. So instead, we talk on the side of a gravel road right in front of a little country cemetery. This is also the spot Raasch meets his farm-to-table distributor.
DALE RAASCH: They've got two or three other places that they stop at that has chickens. And I just feel that it's better not to have them come on our place.
BODEN: Before avian flu, Raasch's chickens were allowed to range freely on his property. Now they have to stay in the shed.
RAASCH: When you come and open the door, they think that they're going to be able to get out and get to eat some green grass and stuff and roam around. And they're really disappointed when they don't get to go out of the shed.
BODEN: Some people think Raasch is going too far, but USDA Secretary Tom Vilsack says the most important thing producers can do now is focus on biosecurity.
TOM VILSACK: Folks have been using pond water, for example, to feed and to water their birds. Well, that's a problem because the pond water could be contaminated. We've had situations where folks are supposed to shower before they go into facility, but the shower doesn't work so they go in anyway.
BODEN: The majority of affected birds have been in Iowa, the country's leading egg producer. Egg prices have started to increase at the retail level. Part of this may be due to hoarding. Bakers, restaurants, food manufacturers and other buyers of liquid eggs are also starting to see a price increase. Costs may not soar because avian flu hasn't struck farmers in other leading egg-producing states like Ohio and Pennsylvania. Michael Osterholm says most troubling is the possibility that this strain could be airborne.
OSTERHOLM: We know for other plant pathogens, infectious agents of plants, that we can see clouds of material literally coming across from Africa, across the equator into South America on the wind. And I think the real question here is if that's what's happening here. If it is, that really poses a unique challenge to us for in terms of trying to prevent future transmission.
BODEN: The USDA says new outbreaks will likely ease this summer because exposure to hot, dry weather and direct sunlight kills the virus. But if it is wild birds carrying the flu, when they migrate south for the winter, we may see a new series of outbreaks. And while the virus has mostly affected egg-laying hens, by fall, turkeys and chickens raised for meat on the East Coast could be affected. For NPR News, I'm Sarah Boden in Des Moines.
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