Highly Pathogenic Avian Influenza (HPAI) viruses are a type of Influenza A virus. While there are dozens and dozens of Influenza A viruses, only a small number are considered Highly Pathogenic Avian Influenza viruses. Most avian influenza viruses are transmitted by wild waterfowl,as they seldom become ill once infected and spread the virus via their feces and respiratory tract.  These viruses may also be transmitted by contaminated feed and equipment.

Read our FAQ’s and find resources below the picture. 



 1.  Is HPAI present in the United States?

In December 2014, 2 different strains of HPAI, H5N2 and H5N8, emerged in the United States. Through June 2015, the spread of these strains led to the destruction of 48 million chickens and turkeys, which are exquisitely susceptible to these viruses. Many of the birds were culled to try to prevent further spread of the disease. In addition, strict biosecurity controls were implemented.

2. What zoo animals are affected by HPAI?

The susceptibility of every species of bird or animals isn’t actually known. Influenza A viruses that cause high mortality in poultry are considered highly pathogenic strains, but the truth is that they may or may not cause disease in zoo birds. Wild waterfowl such as mallards and teal often are implicated in spreading the virus, but seldom become ill. During the current HPAI outbreak, raptors that were accidentally fed infected mallards became ill and succumbed quickly due to infection by HPAI. In previous HPAI outbreaks, caused by a different strain, different bird species and mammals were also susceptible.

3. Can man be affected by HPAI?

The current strains of HPAI circulating in the United States do NOT appear to be zoonotic; meaning that the strains do not seem to transmit between man and
animals. Other strains of HPAI that continue to circulate in Southeast Asia and parts of Africa ARE zoonotic. Since influenza viruses re-assort and re-combine frequently, The Centers for Disease Control and Prevention and veterinarians closely monitor circulating strains of influenza for any signs of zoonotic potential.



For more technical information on avian influenza, see the following link from the American Association of Zoo Veterinarians Infectious Disease Manual: