Fall Migration Could Bring Avian Flu to the East

  • A Canadian goose. Photo: Jennifer C. via Flickr

July 31, 2015

Avian flu has already had a devastating impact on Midwestern chicken and turkey farms. Over 40 million birds have died this year—some killed intentionally in an effort to stop the disease from spreading. So far, flocks in Pennsylvania and Ohio have avoided the disease. But the fall migration of waterfowl—which carry avian flu and spread it to domesticated birds—has some poultry producers worried. This week, Kara Holsopple talked with Margaret Brittingham, a professor of wildlife resources in Penn State’s College of Agricultural Sciences, about how the disease spreads and if it’s heading our way.

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On how migrating birds can spread avian flu

“The natural reservoir for this virus is waterfowl. And they don’t show outward signs of disease. And so what happens is that they’re able to carry it and spread the virus in their droppings, but not be sick themselves.

Last December, we had the first case of highly pathogenic avian influenza, and it was discovered in the western U.S. And for waterfowl, there are four major “flyways” that they use for migration: the Pacific Flyway, which is in the far West; the Central, in the center part of the country;  the Mississippi, which follows the Mississippi river drainage; and the Eastern flyway. And avian influenza was detected in three flyways; it has not yet been detected in the Eastern flyway. But what happens is during the breeding season, many of these birds from different flyways are all mixing together. And so there’s the potential that a bird may have become infected while on the breeding ground. Then as they migrate down, they have the potential to bring that disease into a new area. And the concern is that, as birds migrate, we may be seeing it being brought into areas where it has not been before. I think it’s pretty likely.”

On how avian flu is actually spread

“It spreads via their droppings. So, for instance, our Canada geese—you see droppings around a wetland where they’ve stopped. Those could harbor the disease; also, saliva and nasal excretions. The disease can then persist for up to two weeks in ideal conditions, which are the sort of conditions we might have during the fall. And so the concern is that maybe you would go to a duck pond to watch waterfowl and pick up the virus on your shoe and take it to a new area—or even vehicles coming into areas where there are waterfowl gathering.”

On whether avian flu is a risk to humans and other animals

“Influenza viruses are known for their ability to recombine and resort. That’s why we always have to get a different flu vaccine every year. But at this point, this has not been a human health issue. In terms of wild birds, there’s not a lot that we know about that. We know that it does kill raptors. So hawks and owls are killed by this. One of the first cases was a raptor that was fed waterfowl that had been killed by avian influenza. It got avian influenza and died immediately. There’s a concern for birds like the peregrine falcon, which is a recovering species, which feeds quite heavily on waterfowl. So that would be a species that could be impacted.”