Avian influenza refers to any influenza virus that affects birds. Wild waterfowl, such as ducks and geese, are considered to be the reservoirs for influenza viruses, but they usually do not show any signs of illness. When these viruses infect domestic poultry, such as chickens and turkeys, they will show signs such as sneezing, lack of appetite, and nasal discharge.
This low pathogenic virus occasionally mutates into a new and more lethal highly pathogenic virus in domestic poultry. The highly pathogenic H5N1 subtype of influenza virus, commonly referred to as bird flu, has infected both poultry and humans in many parts of the world but not the Americas.
For additional resources and information please visit the Avian Influenza Homepage.