Influenzavirus A

Influenzavirus A is a genus of a family of viruses called Orthomyxoviridae in virus classification. Influenzavirus A has only one species in it; that species is called "influenza A virus". Influenza A virus causes "avian influenza" (also known as bird flu, avian flu, influenzavirus A flu, type A flu, or genus A flu). It is hosted by birds, but may infect several species of mammals. All known subtypes are endemic in birds. It was first identified in Italy in the early 1900s and is now known to exist worldwide.