Abstract: Avian influenza, also known as bird flu, is an influenza A viral disease that affects and kills many species of birds. It also can affect and kill humans.Two avian influenza viruses of significant concern are the subtype H5N1 virus, which circulates primarily in parts of Asia and Africa, and the subtype H7N9 virus, which has been limited to China.Bird flu diagnosis involves taking virus cultures from infected individuals, which are then subjected to antigen, serologic, or viral genetic amplification and detection techniques.Humans can contract bird flu from exposure to infected bird feces, either during farming or from handling raw poultry during slaughtering processes.Bird flu can be treated with antiviral drugs, but mass production of a vaccine against bird flu is restricted due to antigen production limitations