Avian Influenza A(H5N1)

Learn what you need to know about avian influenza in IDSA’s FAQ for patients and the public.

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Avian influenza A(H5N1), also known as highly pathogenic avian influenza or bird flu, is a disease caused by infection with avian influenza type A viruses. The current bird flu strain is widespread in wild birds worldwide. These viruses can also infect other birds — including poultry like chickens and turkeys — as well as mammals including marine mammals (seals and dolphins), wild and domestic cats, and, recently, dairy cows. Sporadic infections in people have also been reported, usually after exposure to infected poultry or virus-contaminated environments.

The current risk to the general public is considered low because the current strain of this virus cannot easily attach to cells in people’s upper respiratory tract (the nose and throat). This makes it hard for the virus to spread from person to person. However, flu viruses change over time, so there is always the risk of the virus gaining the ability to spread more easily among people. Researchers and public health agencies are monitoring the situation and preparing in case the risk increases. People with job-related or recreational exposure to infected birds or other animals, like dairy cows, are at greater risk of infection and should take precautions to lower their exposure to the bird flu virus.

The primary treatment for avian influenza infection in people is oseltamivir (Tamiflu). Vaccination against seasonal flu will not prevent infection with avian flu viruses but can reduce the risk of getting sick with human and bird flu viruses at the same time. The U.S. government has a modest stockpile of vaccines that are reasonably well-matched for avian flu for emergencies, but these have not yet been deployed because the current risk to the public is considered low.

Milk sold in most grocery stores (with a few exceptions) is pasteurized. Pasteurization kills the bird flu virus and other dangerous microbes by briefly heating milk to high temperatures. Drinking raw (unpasteurized) milk is linked to many preventable foodborne illnesses and is especially unwise during this outbreak of bird flu. Animals, such as cats, who have consumed unpasteurized milk contaminated with the bird virus have become very sick, and some have died.