Avian influenza (AI), or “bird flu,” is a virus that infects domestic poultry, such as chickens, turkeys, quail, and geese, and wild birds such as shorebirds and waterfowl.
AI viruses are divided into two groups—highly pathogenic (HPAI) and low pathogenic (LPAI)—based on the ability of the virus to produce disease and the severity of illness it can cause. HPAI spreads rapidly and has a high death rate in birds. LPAI causes only minor illness and occurs naturally in migratory waterfowl. The concern is that some LPAI virus strains are capable of mutating into HPAI viruses.
HPAI viruses are considered exotic or foreign to the United States because they do not occur naturally here. HPAI has been detected and eradicated by the U.S. Department of Agriculture (USDA) three times: in 1924, 1983, and 2004. The 1983 outbreak resulted in the deaths of about 17 million chickens, turkeys, and guinea fowl in Pennsylvania and Virginia. Managing this outbreak cost nearly $65 million and caused retail egg prices to increase by more than 30 percent.