Researchers have now suggested that southern China may
have been the source for much of the spread of the H5N1 bird flu
Reuters has reported that flu experst have found that a genetic analysis of
the highly pathogenic H5N1 virus shows that strains that appeared in Vietnam,
Thailand and Malaysia in 2002 and 2003 closely resemble a strain from poultry
markets in China's Yunnan Province.
It was reported in the Journal of Virology that the two viruses found in
poultry in China's Hunan province in 2002 and 2003 were most closely related to
viruses from Indonesia.
"These results suggest a direct transmission link for H5N1 viruses between
Yunnan and Vietnam and also between Hunan and Indonesia during 2002 and 2003,"
wrote the researchers*."Poultry trade may be responsible for virus introduction
to Vietnam, while the transmission route from Hunan to Indonesia remains
unclear," they wrote.
The H5N1 bird flu virus was first seen in a goose in southern China's
Guangdong province in 1996. The virus re-emerged in 2003. Since then, H5N1 bird
flu has been found in more than 60 countries and territories. It has killed 236
people out of 373 infected in 14 countries -- Myanmar, Turkey, Djibouti,
Azerbaijan, Egypt, Pakistan, Iraq, Indonesia, Thailand, Vietnam, China, Nigeria,
Laos and Cambodia.
The team of researchers to find out if H5N1 viruses all descend from one
type. "Due to the lack of influenza surveillance prior to these outbreaks, the
genetic diversity and the transmission pathways of H5N1 viruses from this period
remain undefined," they wrote.
In 2007, a team at the University of California Irvine reported that
Guangdong appeared to be the source of renewed waves of the H5N1 strain, but
Chinese officials denied the report at the time.
* Included Guan Yi of the University of Hong Kong and Robert Webster of
St. Jude Children's Research Hospital in Memphis, Tennessee.