Avian influenza (AI) appears periodically all over the world, including in the United States. The virus spreads easily among wild aquatic birds, which are thought to be the natural hosts of avian influenza viruses. Certain strains also can infect domesticated birds (including chickens, turkeys, ducks and, rarely, pet birds); humans (rarely); and a variety of other mammals.
Most outbreaks of avian influenza in the United States have been associated with low pathogenic strains of the virus (LPAI). These strains do not normally cause clinical signs of disease in waterfowl, but may cause mild disease in poultry. Outbreaks are resolved through the combined efforts of veterinarians, the poultry industry, and local, state, and federal governmental agencies.
Surveillance for the influenza virus in multiple animal species, including wild birds, poultry and swine, helps detect the virus early so actions can be taken quickly to protect poultry and prevent the disease from spreading. Additionally, the U.S. Department of Agriculture (USDA), U.S. Centers for Disease Control and Prevention (CDC, and the World Health Organization work closely together to monitor both animal and human influenza viruses.
Highly pathogenic strains of avian influenza virus (HPAI) can devastate entire flocks of poultry and result in major economic losses, and potentially affect people and other animal species. Highly pathogenic strains are highly contagious in poultry, and the birds often show clinical signs of illness. Some strains of avian influenza may be able to infect humans and other animals. Animal and human health authorities worldwide monitor avian influenza viruses for their potential to infect humans. The USDA, the CDC, and the World Health Organization provide information on avian influenza affecting humans.