What is bird flu?
Bird flu, or avian influenza, is an illness caused by avian flu viruses that affect mostly birds. There are many forms of these viruses. Most of them cause only mild symptoms, if any, in birds. These “low pathogenicity” avian flu viruses are found worldwide. They have probably been present in birds for thousands of years or more, and they pose no threat to birds or people. However, some forms of the virus are “highly pathogenic,” causing severe symptoms and death in birds, especially in poultry.
In Africa, Asia, Europe, and the Near East, highly pathogenic H5N1 strains of avian influenza have been deadly to poultry flocks and have caused outbreaks among some wild bird species, especially waterfowl and shorebirds. Some 200 million domestic chickens, turkeys, ducks, and geese have died from the disease or have been destroyed to prevent the spread of the virus. This is a big problem in parts of the world where a large number of people make a significant portion of their living raising poultry.
Humans do not usually become infected with these highly pathogenic H5N1 viruses. However, since 2003 there have been 247 human deaths worldwide from H5N1 avian flu, mostly resulting from close contact with diseased poultry and poultry products. In its current form, the highly pathogenic H5N1 avian flu virus is not easily transmitted from person to person, but health officials fear that the virus could mutate into a form that can spread more easily among humans, causing a human pandemic.