Summary: Highly Pathogenic Avian Influenza Virus H5N1
and Wild Birds
Southeastern Cooperative Wildlife Disease Study
Department of Population Health
College of Veterinary Medicine
The University of Georgia
Updated: April 12, 2006
What are avian influenza viruses?
· Avian influenza viruses (AIV) are Type A influenza viruses that are associated with avian
species. They have been isolated from more than 100 species of free-living birds world-wide.
· Classification of these viruses is based on their hemagglutinin (H) and neuraminidase (N)
subtypes. There currently are 16 H and 9 N recognized subtypes, and all of these subtypes
are represented in viruses isolated from wild birds.
· Wild birds represent the historic source for Type A influenza viruses affecting both domestic bird
and mammalian species.
· The host adaptation that occurs after the movement of these viruses from wild birds to domestic
animals to humans often results in the evolution of "new" viruses that can become adapted to
the new host population. These "new" viruses (which include human Type A influenza viruses)