(Agencies)
Updated: 2004-02-12 13:28

The World Health Organization confirmed on Wednesday that new genetic tests showed no evidence a deadly bird flu that has killed 14 people was passing from person to person.

It said DNA tests on a 23-year-old Vietnamese woman who died of the H5N1 poultry influenza virus showed no evidence she caught it from her sister, who also died.

WHO originally reported the results last week but then recalled them, saying they had in fact tested a different woman.

"WHO has today received the results from a study of virus isolated from a 23-year-old woman who is part of a family cluster in Vietnam under investigation as the first possible instance of human-to-human transmission," WHO said in a statement posted on its Web site.

"Virus genetic material from this woman, as for the other case in this cluster, is of avian origin and contains no human influenza genes."

Experts say the bird flu virus must mutate before it can be passed easily from person to person, although people can clearly catch it from birds.

But recent studies on the virus that caused the 1918 influenza pandemic, which killed 40 million people globally, showed it had mutated very little from its original avian form. This suggests few changes are needed to make any bird influenza virus into an easily passed human pathogen.