Avian influenza overview

Overview

For the H5N1 subtype of Avian influenza see H5N1. Avian influenza, commonly known as Bird flu, is a strain of the influenza virus which infects birds. Most bird flu viruses can only infect other birds. However, bird flu can pose health risks to people. The first case of a bird flu virus infecting a person directly was in Hong Kong in 1997. Since then, the bird flu virus has spread to birds in countries in Asia, Africa and Europe.