Avian flu, or "bird flu," is an infection caused by avian influenza (or "bird flu") viruses. These flu viruses occur naturally among birds. Wild birds worldwide commonly carry the viruses in their intestines or respiratory tracts but usually do not get sick from them. However, bird flu can be contagious among birds and can make some domesticated birds including chickens, ducks, and turkeys - very sick and kill them. The risk to humans of avian flu is generally low to because the viruses occur mainly among birds and do not easily infect humans. However, during an outbreak of avian flu among poultry (including domesticated chicken, ducks, turkeys) there is a possible risk to people who have contact with infected birds or surfaces that have been contaminated with excretions from infected birds that carry the virus.
Avian influenza, or "bird flu", is a contagious disease of animals caused by viruses that normally infect only birds and, less commonly, pigs.