Avian Influenza (Bird Flu)

This page provides information about avian influenza for employers and workers. Visit the CDC Avian Influenza webpage for current situation information.

Photo credit: U. S. Department of Agriculture

Avian influenza (or bird flu) is a disease of birds caused by infection with avian influenza A viruses. Infected birds shed bird flu virus in their saliva, mucous, and feces. People rarely get bird flu; however, human infections with bird flu viruses can happen if enough virus is inhaled or gets into a person’s mouth, eyes, or nose. Bird flu infections happen most often after someone has close, prolonged and unprotected (no gloves or other personal protective equipment) contact with infected birds and then touches their mouth, eyes, or nose.

Domestic poultry may be infected with highly pathogenic avian influenza (HPAI) A viruses or low pathogenic avian influenza (LPAI) A viruses:

The highly pathogenic viruses spread quickly and may kill nearly an entire poultry flock within 48 hours.
The low pathogenic viruses may not cause symptoms or may cause only mild symptoms such as ruffled feathers or a drop in egg production.

The classification of low pathogenic or highly pathogenic avian influenza A virus refers to the ability of the virus to cause disease in chickens in the laboratory, not in humans. Human infection with low pathogenic and highly pathogenic avian influenza A viruses have resulted in a range of symptoms from mild to severe.

Avian influenza A viruses are a public and occupational health concern for several reasons, including:

Some of these viruses have passed sporadically from poultry to humans and caused serious illness and death.
They may change into a form that is highly infectious in humans and spreads easily from person to person.
As these viruses threaten domestic poultry throughout the world, they are also a risk to workers worldwide who have contact with poultry.

Avian influenza A viruses occur naturally among wild aquatic birds worldwide. Avian influenza viruses have also infected other animals, including ducks, chickens, turkeys, pigs, whales, horses, seals, dogs, and cats. Influenza A viruses that infect one animal species may sometimes cross over and cause illness in another species, including people.

For more information: CDC Transmission of Avian Influenza A Viruses Between Animals and People.

Avian influenza A viruses usually do not infect humans; however, sporadic cases have been reported. The disease can be transmitted to unprotected workers who have contact with infected wild birds, poultry, or contaminated materials or surfaces.

Examples of poultry workers and other workers at risk include the following:

Broiler breeder farms, hatcheries, grow-out farms, and processing plant workers
Layer farm workers
Turkey farm workers
Disease control and eradication workers (including Federal, contract, and company workers)
Live-bird market workers
Wildlife biologists who handle birds
Animal welfare and rescue workers who handle infected animals
Animal control workers who handle infected animals

Infected birds shed bird flu virus in their saliva, mucous, and feces. Human infections with bird flu viruses are rare but can happen if enough virus is inhaled or gets into a worker’s mouth, eyes, or nose. This can happen if virus is in the air and a worker breathes it in, or if a worker touches something that has virus on it and then touches their mouth, eyes or nose. Bird flu infections happen most often after someone has close, prolonged and unprotected (no gloves or other personal protective equipment) contact with infected birds and then touches their mouth, eyes, or nose.

The virus may be transmitted to workers from contact with one of the following:

Infected wild birds or poultry that are sick or dead
Droppings of infected birds
Contaminated litter
Contaminated materials or surfaces such as egg collection containers

Protective measures should be taken by anyone likely to have exposure to avian influenza A viruses. For more information: Recommendations for Worker Protection and Use of Personal Protective Equipment (PPE) to Reduce Exposure to Novel Influenza A Viruses Associated with Severe Disease in Humans | Avian Influenza (Flu) (cdc.gov)

See the CDC infographic: How Infected Backyard Poultry Could Spread Bird Flu to People

The signs and symptoms of bird flu virus infections in humans range from no symptoms or mild illness such as eye redness or mild flu-like upper respiratory symptoms to severe illness such as pneumonia requiring hospitalization.

Other symptoms may include:

fever or feeling feverish
cough
sore throat
runny or stuff nose
muscle or body aches
headaches
fatigue
shortness of breath or difficulty breathing.

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

Avian influenza A viruses are routinely detected in wild birds. Around the world and in North America, avian influenza A outbreaks occur in poultry from time to time. Outbreaks of some avian influenza A viruses in poultry have been associated with illness and death in humans in Asia, Africa, Europe, the Pacific, and the Near East. While very rare, some avian influenza A viruses have caused illness in humans in North America.

For more information: CDC avian influenza current situation information.

Responders to an avian influenza outbreak may be at risk of exposure to additional hazards including:

Depopulation and disposal processes may have hazards associated with them such as carbon dioxide exposure, heat exposure, and slips on wet surfaces if proper procedures are not followed.

Water-based Foam Depopulation, Iowa State University Center for Food Security and Public Health
USDA APHIS Highly Pathogenic Avian Influenza Depopulation and Disposal for Birds in Your HPAI-Infected Flock

Avian Influenza (Bird Flu)

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