Avian Influenza

Avian Influenza (H5N1 Bird Flu)

Page originally published 5/1/2024. Last updated 10/4/2024.

Avian influenza (H5N1 Bird Flu) is a disease caused by infection with a type of flu virus. These viruses occur among water birds, like ducks and geese. They can also spread to domestic poultry, like chickens and turkeys, in addition to wild and domestic mammals. Although avian flu does not usually make people sick, there have been some rare cases.

The current outbreaks of H5N1 in U.S. poultry were first detected in the United States in January 2022 with detections in dairy cows in 2024. While the current public health risk is low, the Centers for Disease Control and Prevention (CDC) is watching the situation carefully and working with states to monitor people with animal exposures.

See below, or click the following links, to learn more about:

Prevention
Exposure
Transmission (spread)
Symptoms
Diagnosis
Treatment
Resources
- Avian Influenza in Birds
- Avian Influenza in Pets and Other Animals
Infographic

Prevention

There is no vaccine for humans to prevent avian flu spread. Seasonal flu vaccines will not prevent infection with avian flu viruses.

The best prevention is to avoid sources of exposure whenever possible. Wild birds can be infected with avian flu even if they do not look sick.

Avoid unprotected exposure to sick or dead animals, including animal feces, litter, or materials contaminated by birds or other animals with suspected or confirmed bird flu infection.
Do not touch surfaces that may be contaminated by wild or domestic birds, or other animals, with suspected or confirmed avian flu.
Properly handle and cook poultry and beef to the appropriate temperatures to kill bacteria and viruses.
Do not consume raw milk.
Bird owners and/or people who have backyard or hobbyist flocks should practice steps to prevent disease from getting to healthy animals (biosecurity).
- Visit Animal and Plant Health Inspection Service (usda.gov) to learn more about biosecurity.

Should those with work or recreational exposures encounter an infected, or potentially infected, animal, they should take the following precautions:

If you observe an unusual number of sick or dead birds in your flock contact the Department of Food and Agriculture (CDFA) Sick Bird Hotline: 1-866-922-2473
If you suspect other animals such as livestock are infected with avian influenza contact the Department of Food and Agriculture Ontario Office; (909) 947-5932
Use personal protective equipment (PPE), such as gloves, an N95 respirator or well-fitted mask, fluid resistant coveralls, rubber boots, and eye protection (e.g., goggles or face shield).
Wash hands with soap and water after touching birds.
Avoid touching your mouth, nose, or eyes after contact with birds, surfaces, or materials that may be contaminated.
Change clothes after handling infected, or potentially infected, birds and other animals. Then, throw away the gloves and mask, and wash your hands with soap and water.
Demonstrations of how to use PPE:

For dairy workers:

For poultry workers:

Exposure

People who become sick within 10 days of their exposure to infected, or potentially infected, birds or other animals should isolate at home.

Monitor your health for symptoms of avian influenza.
Separate from others, including household members, and do not go to work or school until the results of your test are confirmed.
If you have been exposed to avian flu, your health department will also reach out to inform you of the exposure.

A reminder, most of the signs and symptoms of avian flu overlap with those of other respiratory illnesses, such as COVID-19 and seasonal influenza.

Visit the Centers for Disease Control and Prevention’s (CDC) What to Know About Bird Flu for information for different groups of people who become sick after contact with infected birds.

If You Find a Sick or Dead Wild Bird or Other Animal:

Avoid unprotected exposure to sick or dead animals, including animal feces, litter, or materials contaminated by birds or other animals.
- Use PPE, such as gloves, a well-fitting mask, and eye protection.
- Wash your hands with soap and water.
Contact the California Department of Fish and Wildlife.
Sick wildlife can be rehabilitated by the San Diego Humane Society’s Project Wildlife program.

Transmission (Spread)

Types of birds that can be infected with avian flu include:

Waterbirds (ducks, geese, swans);
Shorebirds (storks); and/or
Poultry (chickens, turkeys).

Avian flu viruses may spread from infected birds to other animals, and potentially to humans, in two (2) main ways:

Directly, from exposure to saliva, mucous, or feces from infected birds, and/or eating an infected bird.
Through an intermediate host, such as another animal.

Infections among people are rare. However, people can get sick when enough virus gets into a person’s eyes, nose, or mouth, or it is inhaled (breathed in). This can happen through direct and unprotected contact with infected birds and their contaminated environment.

The spread of avian flu from one infected person to a close contact is very rare. However, monitoring human infection and person-to-person spread is very important for public health in the possibility that the virus could change and gain the ability to spread easily between people.

Symptoms

Illness from avian flu can range from no symptoms, mild symptoms, to severe illness.

Mild symptoms include:

Eye redness, and/or

Mild flu-like upper respiratory symptoms.

Severe symptoms include:

Pneumonia requiring hospitalization,

Fever,

Cough,

Runny or stuffy nose,

Headache,

Muscle or body aches,

Sore throat,

Fatigue, and/or

Shortness of breath or difficulty breathing.

Less common signs and symptoms include diarrhea, nausea, vomiting, or seizures.

Diagnosis

If avian flu is suspected, a doctor should consider the following factors:

Overall health and medical history,
Signs and symptoms,
Exposure to birds/poultry, and
Occupation (e.g., farmers/workers, veterinarians, veterinary staff, emergency staff), and
Lifestyle (e.g., backyard bird flock owners).

Laboratory testing is also needed. Avian flu infection is usually diagnosed by collecting a swab from the nose or throat of the sick person. Testing is more accurate when the swab is collected during the first few days of being sick.

Treatment

People with avian flu infection are recommended to be treated as soon as possible with antiviral drugs. Antiviral treatment works best if started as soon as symptoms begin within the 10 days of exposure.