Researchers have found that southern China may be the source of the H5N1 avian flu virus, Reuters reported. Strains of the virus that were found in Vietnam, Thailand and Malaysia in 2002 and 2003 were close matches to a strain from poultry markets in the southern province of Yunnan. Meanwhile, strains that appeared in Indonesia matched those found in Hunan province. The researchers, from the University of Hong Kong and St Jude’s Children Research Hospital in Tennessee, said the results suggested a "direct transmission link" for the virus between Yunnan and Vietnam, and between Hunan and Indonesia in 2002 and 2003. Last year, researchers at the University of California Irvine said that Guangdong was the source of new waves of the virus.