Avian influenza
Alternative Names
Bird flu; H5N1
Definition
Avian influenza is flu infection in birds. The virus that causes the disease in birds can change (mutate) so it can spread to humans.
Causes
The first avian influenza in humans was reported in Hong Kong in 1997. It was called avian influenza (H5N1). The outbreak was linked to chickens.
Since then there have been human cases of avian influenza A (H5N1) in Asia, Africa, Europe, Indonesia, Vietnam, the Pacific, and the near East. Hundreds of people have become sick with this virus. Up to half of the people who get this virus die from the illness.
The chance of a worldwide outbreak in humans goes up the more the avian flu virus spreads.
Your risk of getting the bird flu virus is higher if:
- You work with poultry (such as farmers)
- You travel to countries where the virus is present
- You touch an infected bird
- You eat raw or undercooked poultry meat, eggs, or blood from infected birds
Health care workers and people who live in the same house as people with bird flu may also be at higher risk of infection.
The avian flu virus (H5N1) lives in the environment for long periods of time. Infection may be spread just by touching surfaces that have the virus on them. Birds who were infected with this flu can give off the virus in their feces and saliva for as long as 10 days.
Symptoms
Symptoms of avian flu infection in humans depend on the strain of virus.
The H5N1 virus in humans causes typical flu-like symptoms, such as:
Exams and Tests
If you think you have been exposed to the virus, call your health care provider before your visit. This will give the staff a chance to take steps to protect themselves and other patients during your office visit.
There are tests for the avian flu but they are not widely available. One type of test can give results in about 4 hours.
Your health care provider might also do the following tests:
- Auscultation (to detect abnormal breath sounds)
- Chest x-ray
- Nasopharyngeal virus detection by reverse transcription-polymerase chain reaction (RT-PCR)
- Nasopharyngeal culture
- Throat virus detection by RT-PCR
- White blood cell differential
Other tests may be done to look at how well your heart, kidneys, and liver are working.
Treatment
Treatment varies based on your symptoms.
In general, treatment with the antiviral medication oseltamivir (Tamiflu) or zanamivir (Relenza) may make the disease less severe. You need to start taking the medicine within 48 hours after your symptoms start for it to work.
Oseltamivir may also be prescribed for persons who live in the same house people with avian flu. This may prevent them from getting the illness.
The virus that causes human avian flu is resistant to the antiviral medicines amantadine and rimantadine. These medicines should not be used in the case of an H5N1 outbreak occurs.
People with severe infection may need to be placed on a breathing machine. People infected with the virus also should be kept separate from non-infected people.
Health care providers recommend that people get an influenza (flu) shot This may cut down the chance that the avian flu virus will mix with a human flu virus. This might create a new virus that may easily spread.
The U.S. Food and Drug Administration has approved a vaccine to protect humans from the avian flu. This vaccine could be used if the current H5N1 virus starts spreading between people. The U.S. Federal Government keeps a stockpile of H5N1 vaccine.
Outlook (Prognosis)
The outlook depends on the type of avian flu virus and how bad the infection is. The disease can be fatal.
Possible Complications
- Acute respiratory failure
- Organ failure
- Pneumonia
- Sepsis
When to Contact a Medical Professional
Call your health care provider if you develop flu-like symptoms within 10 days of handling infected birds or being in an area with a known avian flu outbreak.
Prevention
At this time, the U.S. Centers for Disease Control and Prevention (CDC) Does not recommend against travel to countries affected by H5N1.
If traveling to an area that has H5N1 outbreak:
- Avoid visits to live-bird markets
- Use protective clothing and special breathing masks if you work with birds.
- Avoid undercooked or uncooked meat reduces the risk of exposure to avian flu and other foodborne diseases
Current information regarding avian flu is available at: http://www.cdc.gov/flu/avianflu/avian-in-humans.htm.
References
Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD). Avian influenza A virus infection in humans. Last reviewed: June 21, 2012. Accessed: February 4, 2014.
Levin S. Zoonoses. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 336.
Hayden FG. Influenza. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 372.