Three weeks ago, USDA announced two different findings of H5N1 with preliminary information showing the cases were of the low-pathogenic strain of the disease. Final information was returned last week about the Maryland flock; over the weekend USDA announced the Pennsylvania ducks area also confirmed to have the low-path strain.
The USDA National Veterinary Services Laboratory confirmed the presence of the "North American Strain" of low pathogenic H5N1 according to a release issued by USDA and the U.S. Department of the Interior. The wild mallards had been found in Crawford County.
Low-path strains of avian influenza commonly occur in wild birds and typically cause only minor sickness or no noticeable signs of disease in birds. The first tests on the Pennsylvania birds had been carried out Sept. 2.