Bird flu is a disease caused by a virus that can spread from birds to people. To date, most cases have resulted from extended close contact with poultry (e.g., chickens, turkeys, ducks). Some experts believe the virus could change and become easily transmissible among people. This could allow the disease to rapidly infect a large percentage of the global population and possibly lead to a pandemic. However, such a mutation is not believed to have occurred.

Several strains of bird flu exist and the most capable of causing disease to date is the H5N1 strain. Between 2003 and the end of 2007, this strain infected more than 350 people worldwide, with a mortality rate of more than 60 percent according to the World Health Organization (WHO). Human cases have been confirmed in much of Asia and recent infections have occurred in the Middle East and Africa. It is known to be carried by birds throughout most of the Eastern Hemisphere.

The greatest risk factor for bird flu infection is close contact with domesticated birds in areas where the virus is present (primarily Southeast Asia). Humans can also be infected by contact with contaminated cages, ground, and materials such as feed or feathers.

The signs and symptoms of bird flu typically appear within one to five days of exposure. They may include symptoms associated with flu, such as fever, cough, sore throat and muscle aches. Other possible symptoms include eye infections, pneumonia, diarrhea and difficulty breathing. Patients should consult a physician if any of these symptoms develop within a week of visiting an area where bird flu may be present. If confirmed, the disease is treated with neuraminidase inhibitors, a class of antivirals.

There are global efforts under way to reduce the risk that bird flu could become easily transmissible among humans and develop into a pandemic. Flocks of domesticated birds containing infected animals may be destroyed and farms quarantined to prevent further transmission. In addition, the WHO and national health agencies, such as the U.S. Centers for Disease Control and Prevention (CDC), are monitoring cases of bird flu to detect changes in how it is transmitted. Vaccines and new medications are in research and development to prevent and treat bird flu in the future.