Avian influenza refers to the disease caused by infection with avian (bird) influenza (flu) Type A viruses.

These viruses occur naturally among wild aquatic birds worldwide and can infect domestic poultry and other bird and animal species. Avian flu viruses do not normally infect humans. However, sporadic human infections with avian flu viruses have occurred. For more information visit: http://www.cdc.gov/flu/avianflu/