AS CHINA, Vietnam and Thailand reported fresh outbreaks of the H5N1 bird flu that ravaged east Asian poultry farms this year and killed 23 people, researchers in China announced that the virus is a super-fit mutant that has evolved among ducks and chickens over the past two years in southern China.
Close relatives of the H5 flu, whose normal host is ducks, have increasingly infected chickens in southern China, a team at Shantou University in Guangdong and Hong Kong University reports this week. One family of these viruses, which the team calls genotype Z, has replaced all the others, indicating…
