| | What are the concerns about avian influenza A (H5N1) outbreaks in Asia, Europe, the Near East, and Africa
Category: Avian Influenza
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Answer:There is concern that the H5N1 virus could undergo genetic changes that would result in its ability to be easily transmitted between humans. Since the general population has not been exposed to this H5N1 influenza virus strain before, a mutation leading to sustained human-to-human transmission could cause an influenza pandemic.
Although it is not predictable when the next influenza pandemic will occur and what influenza virus strain may cause it, the continued and expanded spread of a highly pathogenic avian H5N1 virus that first began spreading throughout Asia in 2003 represents an important public health threat.
Human influenza A (H5N1) infections were first recognized in 1997 when this virus infected 18 people in Hong Kong, causing 6 deaths. In 2003, a highly pathogenic avian influenza A H5N1 virus (commonly called H5N1 or HPAI H5N1), started spreading in poultry throughout Asia. This H5N1 virus strain has now caused widespread disease in domestic poultry in Asia, parts of Europe, the Near East, and Africa. It also is causing illness and death in a relatively small number of wild birds. In addition to infecting birds, the H5N1 virus has infected and killed other animals and in a small number of cases, it has infected and killed humans.
Illness caused by this H5N1 influenza virus is very rare among people. Since 2003, the World Health Organization (WHO) has confirmed more than 250 H5N1 human infections in 10 countries. The H5N1 virus does not infect humans easily, and if a person is infected, it is very difficult for the virus to spread to another person. However, when serious infections with this virus occur, more than half of the humans known to be infected with this H5N1 virus have died. The majority of people infected with the virus have had direct contact with infected poultry.
The H5N1 virus has raised concerns about a potential human pandemic because: - The virus is widespread in poultry in many countries in Asia and has spread to parts of Europe, the Near East, and Africa;
- The virus has been transmitted from birds to mammals and in some limited circumstances to humans who had close contact with infected poultry;
- Some wild birds and domestic ducks have become infected without showing symptoms and may be carriers or act as viral reservoirs able to infect domestic poultry species;
- A limited number of instances of probable human-to-human transmission has been reported, although none appears to have spread in a sustained way; and
- Genetic studies confirm that H5N1 influenza viruses, like other influenza viruses, continue to evolve.
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Last Updated: 04/04/2007
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