March 25, 2008

Gene study points Southern China as source of bird flu virus in Asia

Experts have found that bird flu strains that appeared in Vietnam, Thailand and Malaysia in 2002 and 2003 closely resemble a strain from poultry markets in China's Yunnan province.

Researchers stated 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, according to Reuters.

The results suggest a direct transmission link for bird flu viruses between Yunnan and Vietnam and also between Hunan and Indonesia during 2002 and 2003, the researchers explained.

Researchers further stated that poultry trade may be responsible for virus introduction to Vietnam, while the transmission route from Hunan to Indonesia remains unclear.

The H5N1 bird flu virus was first discovered in a goose in southern China's Guangdong province in 1996. The virus was again detected in 2003.

Since then, H5N1 bird flu has been found in more than 60 countries and territories, killing 236 people out of 373 infected in 14 countries which include Myanmar, Turkey, Djibouti, Azerbaijan, Egypt, Pakistan, Iraq, Indonesia, Thailand, Vietnam, China, Nigeria, Laos and Cambodia.

The team of researchers also noted that due to the lack of bird flu surveillance prior to the outbreaks, the genetic diversity and the transmission pathways of H5N1 viruses from the period remain undefined.

In 2007, a team from the University of California Irvine reported that Guangdong appeared to be the source of renewed waves of the H5N1 strain. However, Chinese officials denied the report at the time.