Basics of AI: Avian Influenza
Avian influenza (AI) is an infectious respiratory disease that affects a variety of birds. The various strains of virus that cause AI are generally categorized as high or low pathogenicity according to their ability to produce disease. Low pathogenicity avian influenza (LPAI) causes respiratory disease and depression in poultry. Highly pathogenic avian influenza (HPAI) clinical signs include acute mortality, severe respiratory signs, and occasionally neurologic signs.
What animals can be infected with AI?
Chickens and turkeys are most severely affected by HPAI and generally will die if infected. Waterfowl may survive the disease but then become carriers and are able to spread the virus. Other animals including mammals may also contract AI.
How does AI spread?
Bird contact and feces are the most common ways by which AI spreads. Wild birds that migrate can spread the disease when they come into contact with domestic birds. Domestic birds can spread the disease through contact with other birds at live markets and shows, for example. Humans and shared farm equipment can also act as fomites and cause disease spread.
What do birds that have HPAI look like?
In general, infected birds appear sick. They may have diarrhea and a cough. Chickens and turkeys will die quickly from the disease. Ducks and geese may recover but then remain carriers and spread the disease.
How do I know for sure if a bird has AI?
Only a National Animal Health Laboratory Network diagnostic laboratory can provide initial detection of Avian Influenza virus. After initial diagnoses, the sample is submitted to the National Veterinary Services Laboratory in Ames, Iowa, for confirmatory testing.
Is there any treatment for HPAI?
No. Infected birds must be depopulated by authorities to prevent further spread of the disease. A vaccine may prevent the disease, but is not currently permitted in the United States.
If I keep birds, what should I do to protect them?
During an Avian Influenza outbreak, stringent biosecurity measures should be followed. Generally, one should keep backyard flocks from contact with wild birds. Taking birds to live markets or shows increases the risk of your birds contracting a disease. See USDA Defend the Flock Program resources for more information.
How do I protect myself and my family?
Typically, avian influenza viruses do not infect people. However, there have been rare cases of human infection with AI. Illness in humans from AI virus infections have ranged in severity from no symptoms or mild illness to severe disease that resulted in death.
During an HPAI outbreak in the United States, the most general advice is to avoid wild birds, watch any backyard birds for signs of disease, and keep children away from all birds. Health authorities will provide more specific instructions.
What should I do if I must be around birds?
Whenever working with birds, wash your hands frequently with soap, and take the same precautions as for other types of flu.
Can I eat poultry and eggs?
Consumption of poultry and eggs does not lead to human AI infection. Intensive AI monitoring programs are in place to prevent disease transmission. Additionally, the virus is easily killed by cooking temperatures. Always use safe food-handling techniques. Cook eggs until yolks are firm. Only in-shell pasteurized eggs may be used safely without cooking. Cook poultry until there is no pink in the meat and it falls easily from the bone. Utensils and surfaces used to prepare poultry should be washed immediately with soap and water.
What about recent HPAI outbreaks?
In the United States, migratory wild birds are closely monitored for early detection of AI virus. Any outbreak will be immediately contained, and the public will be made aware of the situation. In 2015, an outbreak of Highly Pathogenic Avian Influenza (HPAI) subtype H5N2 occurred. During the 2015 HPAI U.S. outbreak, the virus was detected in 21 states in commercial premise, backyard flocks, wild captive birds, and/or wild birds. Approximately 7.4 million turkeys and 43 million egg-layers/pullet chickens, as well as a limited number of mixed poultry flocks, were affected by HPAI and died from the disease or were depopulated as part of the response. At the time of this writing, the 2022 HPAI outbreak is ongoing; to date 47 states and over 58 million birds have been affected.
Why can't we just vaccinate the birds for this?
Vaccination can be used in some cases to prevent AI. However, because of the large number of subtypes of the virus and its frequent mutation, vaccinating birds is not very useful for controlling the disease.
Is there a vaccine available for people?
Human vaccines are under development but are not available at the time of this writing.
What are the risks to people?
Reported transmission of AI from birds to people has occurred only rarely and only after close contact such as handling of infected birds. The real danger to public health comes from potential changes in the AI virus enabling it to spread from human to human.