What is avian flu?
Avian flu is an infection caused by avian (bird) influenza (flu) viruses. These flu viruses occur naturally among birds. Wild birds worldwide carry the viruses in their intestines, but usually do not get sick from them. However, bird flu is very contagious among birds and can make some domesticated birds, including chickens, ducks, and turkeys, very sick and can kill them. Like a small number of other bird viruses, including the virus that caused the pandemic of 1918, its genetic material (DNA) has been altered in such a way that it is capable of infecting humans.