Avian influenza is caused by the Type “A” influenza virus. This virus can affect several species of food-producing birds (chickens, turkeys, quails, guinea fowl, etc.), as well as pet and wild birds. Avian influenza viruses are divided by subtypes based on two proteins found in the viruses: hemagglutinin, or “H” protein, and neuraminidase, or “N” protein. The Influenza A H9 potentially has nine different subtypes and at least three H9 infections in humans have been confirmed.