Avian influenza is an infectious disease caused by Influenzavirus A that belongs to the genus Alphainfluenzavirus in the Orthomyxoviridae family of -ssRNA virus. Influenzavirus A viruses are species specific and rarely cross the species barrier. However, subtypes H5, H7, and H9 have caused sporadic infections in humans, mostly as a result of direct contact with infected birds. H5N1 high pathogenicity avian influenza virus causes a rapid onset of severe viral pneumonia and is highly fatal.
