Recently, the U.S. Department of Agriculture (USDA) confirmed the presence of two strains of Highly Pathogenic Avian Influenza (HPAI) virus, H5N2 and H5N8, in Oregon and Washington States in migratory water fowl, a captive bird, and a backyard poultry flock. HPAI viruses circulate in wild aquatic birds, often without causing overt disease, but are highly contagious and cause high rates of mortality in domestic poultry. Surveillance for influenza viruses in bird populations is important for implementing effective control and eradication programs to prevent the spread of HPAI virus strains.
In December 2014, surveillance for HPAI viruses increased in the United States following HPAI outbreaks in commercial poultry in British Columbia, Canada. Subsequently, HPAI was identified in three locations in the United States. First, in Washington, HPAI H5N2 was identified in Northern Pintail Ducks. This virus is genetically similar to the HPAI strain identified in poultry in neighboring British Columbia. Second, the USDA confirmed the presence of HPAI H5N8 in a sick captive Gyrfalcon that was fed wild water birds killed by hunters in the same area of Washington. Third, in Oregon, the USDA confirmed HPAI H5N8 in a small backyard poultry flock of guinea fowl and chickens. According to a statement by the Oregon Department of Agriculture, migratory birds frequent a pond and marsh on the property shared with the backyard flock, suggesting that the HPAI H5N8 detected in the backyard poultry flock may have originated in the wild bird population.
A U.S. Geological Survey (USGS) Wildlife Health Bulletin reported that the H5N2 and H5N8 viruses detected in the United States may be related to the HPAI H5N8 strain circulating in wild birds and poultry farms in Asia and Europe in 2014. Ongoing surveillance of commercial poultry operations, wild bird markets, and migratory bird populations will be critical to detect and prevent the spread of these influenza virus strains.
Importantly, neither virus has been found in commercial poultry in the United States, nor have there been any reports of human infections. HPAI H5 is considered to be of low risk to humans – it does not easily infect humans and is not spread easily to other people. The USDA emphasizes that poultry, poultry products, and wild birds are safe to eat if properly handled and thoroughly cooked.