USDA announces first H5N1 avian flu detection in US pigs

 Government authorities have announced the first detection of H5N1 avian influenza in a while, reported at a backyard farm in Oregon where an outbreak in poultry was recently confirmed.

According to a statement from the USDA's Animal and Plant Health Inspection Service (APHIS), the affected farm is located in Rogue County, Oregon, and houses a mix of poultry and livestock, including five pigs, sheep, and goats.

Concerns arose when H5N1 was detected in livestock earlier, raising fears about potential transmission to pigs. This is particularly worrisome because pigs can serve as mixing vessels for zoonotic viruses. However, it's still unclear if the pigs were infected or if the positive nasal swab results stemmed from environmental contamination on the farm.

The pigs shared resources—such as water, housing, and equipment—with infected poultry, factors that could facilitate disease transmission. Although the pigs showed no signs of illness, the Oregon Department of Health and the USDA decided to test them as a precaution. They euthanized the pigs for further diagnostic testing; results have been negatived for two, while results for the remaining two are pending.

"This farm is a non-commercial operation, and the animals were not intended for the commercial food supply. There is no concern regarding the safety of the national pork supply due to this finding," APHIS noted.

The virus was confirmed in the backyard flock on October 25. The Oregon Department of Agriculture reported that 70 birds were humanely euthanized last week, and the area is currently under quarantine.

Initial genetic sequencing at the USDA's National Veterinary Services Laboratories did not indicate any changes in the H5N1 virus that would suggest increased transmissibility to humans.

This H5N1 finding in pigs coincides with a rise in poultry outbreaks across several western states, which is linked to the migration of wild birds along the Pacific Flyway.

Michael Stenholm, PhD, MPH, director of the University of Minnesota's Center for Infectious Disease Research and Policy (CIDRAP), emphasized that it remains uncertain whether the pigs were truly infected or if the nasal samples were contaminated from environmental exposure. He noted that a similar situation occurred in Colorado in 2022 when a poultry worker tested positive during routine nasal swabbing.

The forthcoming necropsy results will clarify whether the pigs were infected and if the virus was present in their lungs. "We'll need to wait and see," Stenholm advised, stressing the importance of careful interpretation of these developments. He added that previous research has suggested that the virus does not easily infect pigs.