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FACTBOX-Bird flu strains have been seen globally
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<TABLE class=artUtilsTop cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><TD>FACTBOX-Bird flu strains have been seen globally
01 May 2006 15:39:08 GMT
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May 1 (Reuters) - Authorities have discovered a mild form of avian influenza at a live bird market in New Jersey, but it is not the deadly H5N1 strain governments around the world are trying to contain, the state's agriculture department said.
None of the birds in the market died from this virus, which is an indicator that the virus was low pathogenic and not harmful to humans.
Here are some facts on the different strains:
* There are dozens of different strains of avian influenza, classified as either highly pathogenic (HPAI) or low pathogenic (LPAI).
* Avian influenza is an infectious disease of birds caused by type A strains of the influenza virus. Influenza A viruses have 16 H (hemagglutinin) subtypes and 9 N (neuraminidase) subtypes.
* Only viruses of the H5 and H7 subtypes are known to cause the highly pathogenic form of the disease. However, not all viruses of the H5 and H7 subtypes are highly pathogenic and not all will cause severe disease in poultry.
* On present understanding, H5 and H7 viruses are introduced to poultry flocks in their low pathogenic form. When allowed to circulate in poultry populations, the viruses can mutate, usually within a few months, into the highly pathogenic form. This is why the presence of an H5 or H7 virus in poultry is always cause for concern, even when the initial signs of infection are mild.
OUTBREAKS:
* There have been only 24 large outbreaks of highly pathogenic avian influenza in birds since 1959. Here is a list of them, provided by the U.S. Department of Agriculture:
1959 - first recorded outbreak of H5N1, in Scotland.
1961 - H5N3, South Africa
1963 - H7N3, England
1966 - H5N9, Canada
1975 - H7N7, Australia
1979 - H7N7, England
1983 - H5N2, United States
1983 - H5N8, Ireland
1985 - H7N7, Australia
1991 - H5N1, England
1992 - H7N3, Australia
1994 - H7N3, Australia
1994 - H5N2, Mexico
1995 - H7N3, Pakistan
1997 - H7N4, Australia
1997 - H5N2, Italy
1996 - H5N1, Asia (Hong Kong, China)
1999 - H7N1, Italy
2001 - H7N3, Pakistan (a continuation of 1995)
2002 - H7N3, Chile
2003 - H7N7, Netherlands
2003 - H5N1, South Korea (continuation of 1996 strain)
2004 - H5N2, United States
2004 - H7N3, Canada
2004 - H5N2, South Africa
2004 - H7N3, Pakistan (same as 1995, 2001 strain)
2005 - H7N7, North Korea
* Both highly pathogenic and low pathogenic avian influenzas can infect humans but rarely do so. H5N1 is unique in its ability to infect humans more often and to cause severe disease.
* An H7N7 low-pathogenic avian flu infected one person in the United States in 1959, for instance, although an outbreak of highly pathogenic H7N7 in 2003 infected 89 people in the Netherlands and killed one.
* H9N2, H7N2, H7N3, and H5N1 avian influenza viruses have all infected human beings but until H5N1 first affected people, in Hong Kong in 1997, these infections rarely caused serious effects.
<TABLE class=artUtilsTop cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><TD>FACTBOX-Bird flu strains have been seen globally
01 May 2006 15:39:08 GMT
</TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>
May 1 (Reuters) - Authorities have discovered a mild form of avian influenza at a live bird market in New Jersey, but it is not the deadly H5N1 strain governments around the world are trying to contain, the state's agriculture department said.
None of the birds in the market died from this virus, which is an indicator that the virus was low pathogenic and not harmful to humans.
Here are some facts on the different strains:
* There are dozens of different strains of avian influenza, classified as either highly pathogenic (HPAI) or low pathogenic (LPAI).
* Avian influenza is an infectious disease of birds caused by type A strains of the influenza virus. Influenza A viruses have 16 H (hemagglutinin) subtypes and 9 N (neuraminidase) subtypes.
* Only viruses of the H5 and H7 subtypes are known to cause the highly pathogenic form of the disease. However, not all viruses of the H5 and H7 subtypes are highly pathogenic and not all will cause severe disease in poultry.
* On present understanding, H5 and H7 viruses are introduced to poultry flocks in their low pathogenic form. When allowed to circulate in poultry populations, the viruses can mutate, usually within a few months, into the highly pathogenic form. This is why the presence of an H5 or H7 virus in poultry is always cause for concern, even when the initial signs of infection are mild.
OUTBREAKS:
* There have been only 24 large outbreaks of highly pathogenic avian influenza in birds since 1959. Here is a list of them, provided by the U.S. Department of Agriculture:
1959 - first recorded outbreak of H5N1, in Scotland.
1961 - H5N3, South Africa
1963 - H7N3, England
1966 - H5N9, Canada
1975 - H7N7, Australia
1979 - H7N7, England
1983 - H5N2, United States
1983 - H5N8, Ireland
1985 - H7N7, Australia
1991 - H5N1, England
1992 - H7N3, Australia
1994 - H7N3, Australia
1994 - H5N2, Mexico
1995 - H7N3, Pakistan
1997 - H7N4, Australia
1997 - H5N2, Italy
1996 - H5N1, Asia (Hong Kong, China)
1999 - H7N1, Italy
2001 - H7N3, Pakistan (a continuation of 1995)
2002 - H7N3, Chile
2003 - H7N7, Netherlands
2003 - H5N1, South Korea (continuation of 1996 strain)
2004 - H5N2, United States
2004 - H7N3, Canada
2004 - H5N2, South Africa
2004 - H7N3, Pakistan (same as 1995, 2001 strain)
2005 - H7N7, North Korea
* Both highly pathogenic and low pathogenic avian influenzas can infect humans but rarely do so. H5N1 is unique in its ability to infect humans more often and to cause severe disease.
* An H7N7 low-pathogenic avian flu infected one person in the United States in 1959, for instance, although an outbreak of highly pathogenic H7N7 in 2003 infected 89 people in the Netherlands and killed one.
* H9N2, H7N2, H7N3, and H5N1 avian influenza viruses have all infected human beings but until H5N1 first affected people, in Hong Kong in 1997, these infections rarely caused serious effects.