H5 and N1 avian influenza found in Pennsylvania wild bird samples

The U.S. Departments of Agriculture and Interior today announced that the presence of the H5 and N1 avian influenza subtypes in samples from wild mallard ducks in Pennsylvania.

Testing has ruled out the possibility of this being the highly pathogenic H5N1 strain that has spread through birds in Asia, Europe and Africa. Test results thus far indicate this is low pathogenic avian influenza (LPAI), which poses no threat to human health.

The ducks were sampled August 28, 2006 in Crawford County, Pennsylvania. The ducks were showing no signs of sickness, which also suggests this is LPAI. The samples were taken by Pennsylvania Game Commission personnel under a cooperative agreement with USDA, as part of an expanded wild bird monitoring program. The Departments of Agriculture and Interior are working collaboratively with States to sample wild birds throughout the U.S. for the presence of highly pathogenic avian influenza (HPAI). As a result of this expanded testing program, USDA and DOI expect to identify additional cases of common strains of avian influenza in birds, which is not cause for concern.

It is possible that these birds were not infected with an H5N1 strain, but instead with two separate avian influenza viruses, one containing H5 and the other containing N1. The confirmatory testing underway at USDA's National Veterinary Services Laboratories will clarify whether one or more strains of the virus are present, the specific subtype, as well as confirm the pathogenicity. These results are expected within two to three weeks and will be made public when completed.

LPAI commonly occurs in wild birds and specifically in mallard ducks. It typically causes only minor symptoms or no noticeable symptoms. These strains of the virus are not a human health concern. This includes LPAI H5N1, commonly referred to as North American H5N1, which is very different from the more severe highly pathogenic H5N1 circulating overseas.

Mallard ducks are among the wild bird populations that are commonly hunted. There is no known health risk to hunters or hunting dogs from contact with low pathogenic forms of avian influenza virus. Nevertheless, hunters are always encouraged to use common sense sanitation practices, such as hand washing and thorough cooking, when handling or preparing wildlife of any kind. DOI has issued guidelines for safe handling and preparation of wild game.