Avian Influenza (Bird Flu)

What is Avian Influenza (Bird Flu)?
Avian influenza is an infection caused by avian influenza (bird flu) viruses. These influenza viruses occur naturally among birds. Wild birds carry the viruses in their intestines but usually do not get sick from them. However, avian influenza is very contagious among birds and can make some domesticated birds, including chickens, ducks, and turkeys, very sick and kill them.

What is Avian Influenza A (H5N1)?
Influenza A (H5N1) virus - also called "H5N1 virus" - is an influenza A virus that occurs mainly in birds, is highly contagious among birds, and can be deadly to them.

Outbreaks of avian influenza H5N1 have occurred the last several years among poultry and wild migratory birds in Asia and Europe. For an archived listing of where avian influenza H5N1 has been reported, go to www.cdc.gov/flu/avian.

How Does Avian Influenza Spread Among Birds?
Infected birds shed influenza virus in their saliva, nasal secretions and feces. Susceptible birds become infected when they have contact with contaminated secretions or excretions or with surfaces that are contaminated by infected birds. Domesticated birds may become infected with avian influenza virus through direct contact with infected waterfowl or other infected poultry, or through contact with surfaces (such as dirt or cages) or materials (such as water or feed) that have been contaminated with the virus.

Do Avian Flu Viruses Infect Humans?
Bird flu viruses do not usually infect humans, but more than 300 confirmed cases of human infection with bird flu viruses have occurred since 1997.

How Serious is Avian Influenza?
Infection with avian influenza viruses in domestic poultry causes two main forms of disease that are distinguished by severity of symptoms. One form, low pathogenic avian influenza virus (LPAI), may go undetected and usually causes only mild symptoms (such as ruffled feathers and a drop in egg production). Another form, highly pathogenic avian influenza virus (HPAI), may cause disease in birds that affects multiple internal organs and has a mortality rate that can reach 90-100 percent of the flock often within 48 hours.

How Do People Become Infected with Avian Influenza Viruses?
Most cases of avian influenza infection in humans have resulted from direct or close contact with infected poultry such as domesticated chickens, ducks, and turkeys or surfaces contaminated with secretions and excretions from infected birds. The spread of avian influenza viruses from an ill person to another person has been reported very rarely, and transmission has not been seen to continue beyond one or two people.

What Are the Symptoms of Avian Influenza in Humans?
Symptoms of avian influenza in humans have ranged from typical human influenza-like symptoms (fever, cough, sore throat and muscle aches) to eye infections, pneumonia, severe respiratory diseases (such as acute respiratory distress syndrome), and other severe and life-threatening complications. The symptoms of avian influenza may depend on which specific virus and strain caused the infection.

How is Avian Influenza in Humans Treated?
Laboratory studies suggest that the prescription medicines approved for human influenza viruses should work in treating avian influenza infection in humans. However, influenza viruses can become resistant to these drugs, so these medications may not always work.

What are the Risks of Avian Influenza to Human Health?
Two main risks for human health from avian influenza are (1) the risk of direct infection when the virus passes from the infected bird to humans, sometimes resulting in severe disease; and (2) the risk that the virus – if given enough chances – will change into a form that is highly infectious for humans and spreads easily from person to person.

Does the Current Seasonal Flu Vaccine Protect Against Avian Influenza?
No. Influenza vaccine for the current season does not provide protection against avian influenza.

Is There a Risk for Becoming Infected with Avian Influenza by Eating Poultry?
There is no evidence that properly cooked poultry or eggs can be a source of infection for avian influenza viruses. The U.S. government carefully controls domestic and imported food products, and in 2004 issued a ban on importation of poultry from countries affected by avian influenza viruses, including the H5N1 strain. The ban still is in place.

What Precautions Can Be Taken to Reduce the Risk for Infection from Wild Birds?
As a general rule, the public should observe wildlife, including wild birds, from a distance. This protects you from possible exposure to illnesses and minimizes disturbance to the animal. Avoid touching wildlife. If there is contact with wildlife do not rub your eyes, eat, drink, or smoke before washing your hands with soap and water. Do not pick up diseased or dead wildlife.

What Precautions Can Hunters Take to Reduce the Risk of Infection?
Hunters should follow routine precautions when handling game, including wild birds. The National Wildlife Health Center recommends that hunters:

  • Not handle or eat sick game.
  • Wear rubber or disposable latex gloves while handling and cleaning game; wash hands with soap and water or with alcohol-based hand products; and thoroughly clean knives, equipment and surfaces that come in contact with game.
  • Not eat, drink, or smoke while handling animals.
  • Cook all game thoroughly.


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Last updated May 20, 2015