Source and Transmission

What is avian influenza?
  • Avian influenza (AI) is an infectious disease caused by type A influenza virus. There are three types of influenza virus: A, B, and C.1,6
  • All influenza viruses affecting domestic animals (horses, pigs, poultry, etc.) belong to type A, which is also responsible for causing the most serious epidemics in humans. Influenza types B and C mainly affect humans.
  • AI virus is carried in the intestines of wild migratory waterfowl such as geese, ducks, and shorebirds. These birds are a natural reservoir for type A influenza because the virus generally does not cause disease in these species.

Which birds are susceptible to AI infection?
  • More than 60 different species of domestic, wild, and pet birds may be affected by avian influenza.
  • However, domesticated poultry, such as chickens, ducks, quails, pheasants, guinea fowl and turkeys are highly susceptible to infection.

AI Reservoir and Host Transmission
AI Host Transmission
Figure Credit: Dr. Daniel Perez

How do birds get avian influenza?

  • Infected birds shed the influenza virus in their saliva, nasal secretions, and feces.
  • Birds may become infected with avian influenza virus through direct contact with contagious waterfowl or other infected poultry, or through indirect contact with contaminated surfaces such as dirt, cages, or materials like feed and water.
  • Rodents and insects may also physically carry the virus around coops.

CDC Image Library: Cynthia Goldsmith