Bird Flu Pandemic Facts: Asia Outbreak
Why is there concern about the H5N1 avian influenza outbreak in Asia and other countries?
Although it is unpredictable when the next pandemic will occur and what strain may cause it, the continued and expanded spread of a highly pathogenic—and now endemic—avian H5N1 virus across eastern Asia and other countries represents a significant threat.
Avian H5N1 influenza infection in humans was first recognized in 1997 when this virus infected 18 people in Hong Kong, causing 6 deaths. Concern has increased in recent years as avian H5N1 infections have killed large numbers of poultry flocks and other birds in Asia and Europe. Since 2003, more than 100 human H5N1 cases have been reported in Thailand, Vietnam, Cambodia, and Indonesia, and more than half have died.
The H5N1 virus has raised concerns about a potential human pandemic because:
- The H5N1 virus is widespread in poultry in many countries in Asia and has spread to Europe;
The virus has been transmitted from birds to mammals and in some limited circumstances to humans;
Wild birds and domestic ducks have been infected without showing symptoms and become carriers of viral infection to other domestic poultry species;
There a few cases of human-to-human transmission have been reported; and
Genetic studies confirm that H5N1 influenza viruses, like other influenza viruses, are continuing to evolve.
For more information, see the U.S. Health and Human Services website on Avian Flu Pandemic.