for National Geographic News
Bird flu is spreading steadily westward from its Asian source and raising anxiety in its wake.
In February alone the deadly H5N1 strain of avian flu affected birds in Italy, Greece, Bulgaria, Germany, Austria, France, Slovenia, India, Iran, and Egypt.
To date the World Health Organization (WHO) has confirmed 184 cases of H5N1 in humans and 103 deaths.
Just how dangerous is the disease? Our frequently asked questions separate bird flu fact from fiction:
What is bird flu?
Avian influenza (bird flu) is an infection caused by contagious viruses that are common among birds. Wild birds may carry these infections, but they typically prove most harmful to domestic fowl like chickens, ducks, and turkeys.
Highly potent forms of the virus can quickly kill 90 to 100 percent of infected birds.
The best known strain of bird flu is a variation of H5N1, a highly contagious and deadly bird virus. This virus has also infected people. The first known human case of bird flu appeared in Hong Kong in 1997. Recently humans have become infected in Indonesia, Vietnam, Thailand, Cambodia, China, Turkey, and Iraq.
How do humans get bird flu?
Nearly all humans who have been diagnosed with bird flu had close contact with infected domestic birds (chickens, ducks, or turkeys), or areas contaminated with their excrement and secretions.
It's important to remember that this poultry-based virus is not easily transmitted to humans. Frequently, even people who come into contact with infected birds do not acquire the virus.
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