A backyard pig in the American state Oregon has been found positive for avian influenza A, type H5N1, according to the US Department of Agriculture. The discovery constitutes the first-known case of the virus emerging in swine.
The finding occurred on a non-commercial backyard operation in Crook County, OR, which has “a mix of poultry and livestock, including swine” on-site. Currently the USDA’s Animal Plant and Health Inspection Service (APHIS) and the Oregon state veterinary officials are investigating the positive cases.
70 birds found positive for H5N1
In total 70 birds on the farm were already found positive for the highly contagious H5N1 on October 25 by the Oregon Veterinary Diagnostic Laboratory (OVDL) at Oregon State University (OSU). USDA’s National Veterinary Services Laboratories (NVSL) confirmed the results. The birds were culled.
Last Tuesday, 1 of the 5 pigs on the farm were found to be infected as well, when doing checks. The backyard animals had been using shared water sources, housing and equipment. As that combination proved to enable transmission between species in other cases, the USDA wrote in its press release, the 5 pigs were tested as well.
No signs of illness with pig
The infected pig did not display signs of illness, APHIS wrote in a press release. The swine were euthanised to facilitate additional diagnostic analysis. Test results were negative for 2 of the pigs, and test results are still pending for 2 others. The pigs’ remains were incinerated.
The US authorities emphasise that the farm’s animals were not intended for the commercial food supply. The farm was quarantined to prevent further spread of the virus. Other animals, including sheep and goats on the farm, remain under surveillance.
Genomic sequencing of the H5N1 virus
In addition, the NVSL conducted genomic sequencing of virus from the poultry infected on this farm. The sequencing has not identified any changes to the H5N1 virus that would suggest to USDA and CDC that it is more transmissible to humans.
The USDA noted that so far, it has approved 2 vaccine field safety trials for vaccine candidates designed to protect dairy cows from H5N1, and continues to explore vaccine options for other species.