Bird flu (avian influenza)
Bird flu (avian influenza)
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.
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:
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 seek medical advice
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.
The greatest risk factor for bird flu seems to be contact with sick birds or with surfaces contaminated by their feathers, saliva or droppings. The World Health Organization (WHO) has confirmed a handful of cases of limited human-to-human transmission of bird flu. But unless the virus begins to spread more easily among people, infected birds or associated material presents the greatest hazard.
The pattern of human transmission remains mysterious. Young children seem especially vulnerable to the virus, although some experts note that children are more likely to have contact with sick birds or to play on ground contaminated with droppings. What's more, 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.
People with bird flu may develop life-threatening complications, including:
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 tens of thousands of deaths each year in the United States alone.
Preparing for your appointment
If you suspect that you have bird flu, you need to see your family physician. If you are very ill, you may need to be hospitalized.
What you can do
What to expect from your doctor
Tests and diagnosis
Treatments and drugs
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.
Bird flu vaccine
Researchers continue to work on other types of bird flu vaccines. One of the stumbling blocks is that most vaccines need chicken eggs for their development and production. Bird flu viruses are lethal to chicken eggs.
Recommendations for travelers
Poultry and egg products
Last Updated: 2009-11-07
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