Bird Flu Sources Still Up For Debate

December 6, 2016 12:54 PM

In 2015, the U.S. was battling its own highly pathogenic strain of avian flu in the Midwest, now it’s Japan and Europe’s turn. St. Jude Children’s Research Hospital, Ohio State University and the Univeristy of Georgia is shedding light on how these strains are carried and spread.

Greg Langmo, a Minnesota turkey producer, received some news he’ll never forget in April 2015.

“My manager called and said the birds don’t look right I thought, ‘Uh oh,’” said Langmo.

His flock was just one of over 200 commercial flocks infected by H5 Avian Influenza, which USDA said killed more than 50 million birds. Now, there’s a debate over wild birds and how much they should be to blame for highly pathogenic cases.

While wild ducks and other ducks are known to be natural hosts for low path viruses, some researchers say the deadlier high path strains do not persist in wild birds.

“Certainly wild birds can introduce low path AI into poultry populations and then it can mutate into high path but it looks like wild birds are not the primary reservoir maintaining the virus in the highly pathogenic form,” said Andrew Bowman, a professor of veterinary preventative medicine at Ohio State University.

“It just seems logical to think that if they can support the low path, then they should support the high path,” said Dr. Robert Webster, a researcher with St. Jude. “It’s taken many years to realize that the wild birds of the world simply don’t maintain the high path viruses.”

Researchers took throat swabs and other samples from more than 22,000 wild ducks and birds in Canada, the Mississippi Flyway and along the Atlantic Coast before and during the 2014 and 2015 avian flu outbreak.

None of the migratory birds in the analysis were infected with the highly pathogenic flu virus.

“We’re not saying wild birds don’t play a role but certainly it’s a different thinking than what we’ve had before that wild birds are going to spread it everywhere,” said Bowman.

However, representatives with USDA Animal and Plant Health Inspection Service (APHIS) disagree. They said the global spread has been circulating within migratory waterfowl. Representatives with APHIS said they discovered the high path strain in 98 wild birds from December 2014 through June 2015.

The majority were hunter harvested water fowl found in the Pacific Flyway. More were found this year. Representatives told AgDay, wild waterfowl are often infected with AI viruses and do not usually show the signs of disease.

Despite the debate, both say biosecurity is key. APHIS says it’s more likely viruses are spread by contaminated feed, clothing or equipment.

“If we look at the Indiana case with the high path H7, that was a low path virus,” said Bowman. “We have evidence of that within the wild bird population. It was introduced into poultry and then mutated to a high path form. Biosecurity is the main way we’re going to keep that from happening.”

Researchers say their work is far from over.

“I don’t see that we’re going to remove the threat of influenza at this point,” said Bowman. “The virus changes too quickly and therefore, we’re constantly playing catchup with the virus.” 

“Whether you’re a cattleman, or raise sheep or corn; it’s a passion,” said Langmo. “It’s a way of life.”

It’s a livelihood many embrace and one reason producers like Langmo hope the virus doesn’t strike in his area again.

Representatives with APHIS told AgDay since this St. Jude study, researchers have since detected the high path H5N2 in an Alaskan mallard. They said it proves these viruses are circulating in wild birds. The European outbreak of high path H5N8 is also believed to be from wild birds in Europe. 

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