What is h5n1?

Avian influenza: Since late 2003, avian influenza virus h5n1 has caused outbreaks among poultry across eurasia and appears to have become established as an endemic virus in poultry and ducks. Most cases of human infection have involved close contact with infected poultry, particularly sick or dying chickens. H5n1 refers to the classification of the virus based on its hemagluttinin and neuraminidase antigens.