Avian influenza (bird flu) is an infection caused by viruses. These flu viruses occur naturally among birds. Wild birds worldwide carry the viruses in their intestines, but usually do not get sick from them. Avian influenza (bird flu) is very contagious among birds and can make some domesticated birds, including chickens, ducks, and turkeys, very sick and kill them. Infected birds shed flu virus in their saliva, nasal secretions, and feces. Susceptible birds become infected when they have contact with contaminated excretions or surfaces that are contaminated with excretions.

Bird flu viruses do not usually infect humans, but several cases of human infection with bird flu viruses have occurred since 1997.

• The risk from bird flu is generally low to most people because the viruses occur mainly among birds and do not usually infect humans.
• It is believed that most cases of bird flu infection in humans have resulted from contact with infected poultry or contaminated surfaces.
• During an outbreak of avian influenza (bird flu) among poultry (domesticated chicken, ducks, turkeys), there is a possible risk to people who have contact with infected birds or surfaces that have been contaminated with excretions from infected birds.

Avian influenza viruses may be transmitted to humans in two main ways:

• Directly from birds or from avian virus-contaminated environments to people.
• Through an intermediate host, such as a pig.

Symptoms of bird flu in humans include:

• Flu-like symptoms (fever, cough, sore throat and muscle aches)
• Eye infections
• Pneumonia, severe respiratory diseases (such as acute respiratory distress)
• Other severe and life-threatening complications.
• The symptoms of bird flu may depend on which virus caused the infection.

No conclusive evidence of sustained human-to-human transmission has been found.

Studies suggest that the prescription medicines approved for human flu viruses would work in preventing bird flu infection in humans.

When avian influenza outbreaks occur in poultry, quarantine and depopulation (or culling) and surveillance around affected flocks is the preferred control and eradication option.

Additional Information

PandemicFlu.gov: View the official US government website for information on pandemic flu and avian influenza.
Centers for Disease Control and Prevention: Get the latest information on avian influenza.
CDC's Germstopper Campaign: Learn healthy habits to prevent the spread of germs at home, school, and work.