Tests confirm low pathogenic H5N1 avian influenza in in Pennsylvania ducks

The U.S. Departments of Agriculture and Interior has announced final test results, which confirm that low pathogenic H5N1 avian influenza virus was found in samples collected last month from wild mallard ducks in Pennsylvania.

This subtype has been detected several times in wild birds in North America and poses no risk to human health.

The USDA National Veterinary Services Laboratories (NVSL) confirmed the presence of the "North American strain" of low pathogenic H5N1 avian influenza through virus isolation in one of the 15 samples collected from the wild mallards in Crawford County, Pennsylvania. Initial screening results announced on Sept. 2 indicated that an H5N1 avian influenza subtype was present in the collected samples, but further testing was necessary to confirm pathogenicity. As previously announced, genetic testing ruled out the possibility that the samples carried the specific highly pathogenic strain of H5N1 avian influenza that is circulating overseas.

Low pathogenic strains of avian influenza commonly occur in wild birds and typically cause only minor sickness or no noticeable signs of disease in birds. Low pathogenic H5N1 is very different from the more severe highly pathogenic H5N1 circulating in parts of Asia, Europe and Africa. Highly pathogenic strains of avian influenza spread rapidly and are often fatal to chickens and turkeys.

The Departments of Agriculture and Interior are working collaboratively with States and academic institutions to sample wild birds throughout the United States for the presence of highly pathogenic avian influenza.