California Department of Fish and Wildlife

Facts about Avian Influenza

Current Facts about Highly Pathogenic H5N1 Avian Influenza in North America for people who have regular contact with wild birds.

Hunters, backyard bird feeders, wildlife rehabilitators, gamebird breeders, licensed game bird clubs, falconers, restricted species permit holders, scientific collectors, zookeepers, and field biologists are examples of people who can have contact with wild birds.

  • As of August 1, 2006, one report of potential transmission of HPAI H5N1 from wild bird to human has been made. In this case, infection from wild swans being de-feathered in Azerbaijan was the most likely source of the human infection.
  • In the United States, there is currently no known risk of being exposed to the HPAI H5N1 virus through contact with wild birds.
  • There is currently no evidence to suggest that the HPAI H5N1 virus is present anywhere in North America. However, it could eventually arrive via migratory wild birds, illegal importation of infected poultry or captive exotic birds, or from infected travelers and/or their contaminated belongings entering California on direct flights from regions where the HPAI H5N1 virus is prevalent.
  • Avian disease outbreaks are a naturally occurring event in California; causes of wild bird disease die-offs include: avian botulism, avian cholera, mycoplasmosis, salmonellosis, trichomoniasis, among others.
  • Wild waterfowl are the natural reservoirs for avian influenza viruses. These birds carry the virus in their intestines and shed it in their feces. Susceptible birds become infected by contact with infected feces and avian influenza virus-contaminated water. Most avian influenza viruses have been isolated from water birds, specifically Anseriformes (ducks, geese, swans) and Charadriiformes (gulls, terns and shorebirds), and to a lesser extent, Passeriformes (perching birds that make up about 60 percent of all bird species). In ducks, AI infection peaks in the late summer and early fall and in gulls and shorebirds, peak infection rates are associated with spring migration.
  • Long-term surveillance of more than 30 years by the U.S. Geological Survey and U.S. Fish and Wildlife Service in cooperation with CDFW, has not established the presence of any HPAI virus in North American wild birds. Surveillance has targeted not just avian influenza viruses, but monitoring for many avian diseases.