H5N1 avian flu was detected in pigs for the first time in the United States

Pigs pose a particular problem for the spread of avian influenza because they can become infected with both avian and human viruses.

Reuters

October 31, 2024, 13:55

Last modified: October 31, 2024 1:57 pm

In this June 10, 2024 illustration, test tubes with the word “Bird Flu” are visible in front of the U.S. flag. REUTERS/Dado Ruvic/Illustration/File Photo

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In this June 10, 2024 illustration, test tubes with the word “Bird Flu” are visible in front of the U.S. flag. REUTERS/Dado Ruvic/Illustration/File Photo

H5N1 bird flu has been confirmed in a pig on a backyard farm in Oregon, marking the first detection of the virus in pigs in the country, the U.S. Department of Agriculture said Wednesday.

Pigs pose a particular problem in terms of the spread of avian influenza because they can become infected together with avian and human viruses, which can swap genes to create a new, more dangerous virus that can more easily infect humans.

The USDA said the Oregon case does not threaten the country’s pork supply and that the risk of bird flu to the public remains low.

Pigs were the source of the 2009-2010 H1N1 flu pandemic and have been implicated as the source of others, said Richard Webby, a virologist at St. Jude Children’s Research Hospital who studies influenza in animals and birds for the World Health Organization.

Finding the virus on a small farm makes it less dangerous to infect pigs than if it were found on a commercial hog farm, he said.

“I think it probably doesn’t increase the risk much, but certainly if this virus starts to be transmitted to pigs, it will absolutely increase the risk,” he said.

The Oregon farm has been quarantined and other animals, including sheep and goats, are being monitored, according to the USDA.

The farm’s pigs and poultry were culled to prevent the spread of the virus and to allow for more testing of the pigs, according to the USDA. Tests on the two pigs are still pending, the agency said.

The pig incident came from wild birds and not from a poultry or dairy farm, a USDA spokesman said. Migration of wild birds has introduced avian influenza into poultry and cattle herds.

The case was one of the factors that prompted the USDA to expand bird flu surveillance to include nationwide milk testing, the agency announced on Wednesday, Agriculture Secretary Tom Vilsack told Reuters.

“Although this is a different variant of the virus and is associated with wild birds, this is a factor in making sure we understand and assess exactly where the virus is in dairy products and cattle,” he said.

The pigs at the Oregon farm were not intended for commercial food supply, the USDA said.

Still, the discovery weighed on lean pork futures prices on the Chicago Mercantile Exchange, a trader said.

Birds and pigs on the backyard farm shared water sources, housing and equipment that served as routes for transmission of the virus between animals in other states, the agency said.

The finding is a warning to pig farmers to watch closely for possible infections, said Marie Culhane, a professor of veterinary folk medicine at the University of Minnesota who has studied influenza viruses in pigs.

“People need to start expanding their plans to deal with this if it happens in another herd and in another herd,” Culhane said. “Pigs are really good at catching flu viruses.”

This year, 36 people have tested positive for bird flu as the virus spread to nearly 400 dairy herds. All but one of the individuals were agricultural workers who had contact with infected animals.

The virus has killed more than 100 million poultry since 2022 in the country’s largest avian flu outbreak.