Mayo Clinic Health Library

Bird flu (avian influenza)

Updated: 01-26-2013

Definition

Bird flu is caused by a type of influenza virus that rarely infects humans. But when bird flu does strike humans, it's often deadly. More than half the people who become infected with bird flu die of the disease.

In recent years, outbreaks of bird flu have occurred in Asia, Africa and parts of Europe. Most people who have developed symptoms of bird flu have had close contact with sick birds. In a few cases, bird flu has passed from one person to another.

Health officials worry that a global outbreak could occur if a bird flu virus mutates into a form that transmits more easily from person to person. Researchers are working on vaccines to help protect people from bird flu.

Next

Symptoms

Signs and symptoms of bird flu typically begin within two to five days of infection. In most cases, they resemble those of conventional influenza, including:

  • Cough
  • Fever
  • Sore throat
  • Muscle aches

Some people also experience nausea, vomiting or diarrhea. And in a few cases, a mild eye infection (conjunctivitis) is the only indication of the disease.

When to see a doctor
See your doctor immediately if you develop a fever, cough and body aches, and have recently traveled to a part of the world where bird flu occurs. Be sure to let your doctor know if you visited any farms or open-air markets.

PreviousNext

Causes

Bird flu occurs naturally in wild waterfowl and can spread into domestic poultry, such as chickens, turkeys, ducks and geese. The disease is transmitted via contact with an infected bird's feces, or secretions from its nose, mouth or eyes.

Open-air markets, where eggs and birds are sold in crowded and unsanitary conditions, are hotbeds of infection and can spread the disease into the wider community.

According to the Food and Drug Administration, bird flu cannot be transmitted by eating properly cooked poultry meat or eggs from infected birds. Poultry meat is safe to eat if it's been cooked to an internal temperature of 165 F (74 C). Eggs should be cooked until the yolk and white are firm.

PreviousNext

Risk factors

The greatest risk factor for bird flu seems to be contact with sick birds or with surfaces contaminated by their feathers, saliva or droppings. In very few instances, bird flu has been transmitted from one human to another. But unless the virus begins to spread more easily among people, infected birds present the greatest hazard.

The pattern of human transmission remains mysterious. People of all ages have contracted and died of bird flu. At this point, too few people have been infected to know all the possible risk factors for bird flu.

PreviousNext

Complications

People with bird flu may develop life-threatening complications, including:

  • Pneumonia
  • Collapsed lung
  • Respiratory failure
  • Kidney dysfunction
  • Heart problems

Although bird flu kills more than half the people it infects, the number of fatalities is still low because so few people have had bird flu. According to the World Health Organization, a few hundred people have died of bird flu since 2003.

In contrast, the Centers for Disease Control and Prevention estimates that seasonal influenza is responsible for thousands of deaths each year in the United States alone.

PreviousNext

Preparing for your appointment

If you suspect that you have bird flu, you need to see your family doctor. If you are very ill, you may need to be hospitalized.

What you can do
You may want to write a list that includes:

  • Detailed descriptions of the symptoms
  • Record of recent travel to an area where bird flu is prevalent
  • Information about past medical problems
  • Information about the medical problems of parents or siblings
  • Questions you want to ask the doctor

What to expect from your doctor
Your doctor may ask some of the following questions:

  • When did you start feeling ill?
  • Have you had a fever? If so, how high has it gotten?
  • Have you had any close contact with birds recently?
  • Have you traveled abroad recently? If so, where did you go?
PreviousNext

Tests and diagnosis

Laboratory tests
Samples of fluids from your nose or throat can be tested for evidence of bird flu virus. These samples must be taken within the first few days after symptoms appear. Depending upon the type of test, results can take weeks or just a few hours.

Imaging tests
X-rays may be useful in assessing the condition of your lungs, which can help determine the proper diagnosis and the best treatment options for your signs and symptoms.

PreviousNext

Treatments and drugs

Medications
Many influenza viruses have become resistant to the effects of a category of antiviral drugs that includes amantadine and rimantadine. Health officials recommend the use of oseltamivir (Tamiflu) and possibly zanamivir (Relenza) instead.

These drugs must be taken within two days after the appearance of symptoms, something that may prove logistically difficult on a worldwide scale, even if there were enough to go around. Because they're in short supply, it's not entirely clear how flu drugs would be allocated if there were a widespread epidemic.

PreviousNext

Prevention

Bird flu vaccine
The Food and Drug Administration has approved one vaccine to prevent infection with one strain of H5N1 bird flu virus. This vaccine isn't available to the public, but the U.S. government is stockpiling it and will distribute it in the event of an outbreak. It's intended to help protect adults ages 18 to 64 and could be used early in such an outbreak to provide limited protection until another vaccine — designed to protect against the specific form of the virus causing the outbreak — is developed and produced. Researchers continue to work on other types of bird flu vaccines.

Recommendations for travelers
If you're traveling to Southeast Asia or to any region with bird flu outbreaks, consider these public health recommendations:

  • Avoid domesticated birds. If possible, avoid rural areas, small farms and open-air markets.
  • Wash your hands. This is one of the simplest and best ways to prevent infections of all kinds. Use an alcohol-based hand sanitizer containing at least 60 percent alcohol when you travel.
  • Ask about a flu shot. Before traveling, ask your doctor about a flu shot. It won't protect you specifically from bird flu, but it may help reduce the risk of simultaneous infection with bird and human flu viruses.

Poultry and egg products
Because heat destroys avian viruses, cooked poultry isn't a health threat. Even so, it's best to take precautions when handling and preparing poultry, which may be contaminated with salmonella or other harmful bacteria.

  • Avoid cross-contamination. Use hot, soapy water to wash cutting boards, utensils and all surfaces that have come into contact with raw poultry.
  • Cook thoroughly. Cook chicken until the juices run clear, and it reaches a minimum internal temperature of 165 F (74 C).
  • Steer clear of raw eggs. Because eggshells are often contaminated with bird droppings, avoid foods containing raw or undercooked eggs.
Previous

Site view: at a glance