November 5, 2024

Livestock farm in Oregon, US, under investigation for positive H5N1 case

The US Department of Agriculture (USDA) and Oregon state veterinary officials are investigating positive cases of H5N1 in a backyard farming operation in Oregon, the United States, that has a mix of poultry and livestock, including swine.

The Oregon Department of Agriculture announced on October 25, that poultry on this farm represented the first H5N1 detection in Crook County, Oregon. On October 29, the USDA National Veterinary Services Laboratories also confirmed one of the farm's five pigs to be infected with H5N1, marking the first detection of H5N1 in swine in the US.  

The livestock and poultry on this farm shared water sources, housing, and equipment. In other US states, this combination has enabled transmission between species.

Although the swine did not display signs of illness, the Oregon Department of Health and USDA tested the five swine for H5N1 out of an abundance of caution and due to the presence of H5N1 in other animals on the premises.

The swine were euthanised to facilitate additional diagnostic analysis. Test results were negative for two of the pigs, and test results are still pending for two others.  According to the University of Minnesota's Center for Infectious Disease Research and Policy (CIDRAP), it is not yet clear if the pigs had systemic infection or if contamination on the farm led to positive nasal swab results.

The farm is a non-commercial operation, and the animals were not intended for the commercial food supply. There is no concern about the safety of the nation's pork supply as a result of this finding.     

The farm has been quarantined to prevent further spread of the virus. Other animals, including sheep and goats on the farm, remain under surveillance.  

The USDA's National Veterinary Services Laboratories (NVSL) has conducted genomic sequencing of virus from the poultry infected on this farm, and that sequencing has not identified any changes to the H5N1 virus that would suggest to USDA and CDC that it is more transmissible to humans, indicating that the current risk to the public remains low.

- USDA