Asian Bird Flu Mutating into
Genuine Transmission Threat

he deadly southeast Asian bird flu that scientists fear could unleash a global epidemic is mutating in ways that could make it more likely to become transmittable between humans, according to a report from the World Health Organization.

WHO investigators reported that although they are unable to prove human-to-human transmission of the virus, they said "the pattern of disease appeared to have changed in a manner consistent with this possibility."

WHO's report was produced after a group of infectious disease specialists met in Manila last month to discuss the latest finding about the bird flu.

The virus, known to scientists as H5N1, first jumped to humans in Hong Kong in 1997. It affects mostly birds, but has been found in other mammals, including cats, pigs, and mice. Experts believe the virus has always been transmitted through direct contact with birds.
But the virus has mutated since 1997, raising fears that it might one day become transmittable between humans, setting off a worldwide pandemic. The flu it causes is 70 percent fatal.

So far, scientists are aware of 97 cases of bird flu in humans in Vietnam, Thailand, Hong Kong, and Cambodia.

Recently, more clusters of infections involving household members have occurred, opening the possibility that "person to person transmission" may have taken place, said the WHO report.
"What we are seeing so far is a slight increase in clusters which could indicate more transmission," said Klaus Stohr, WHO's global influenza program coordinator.

The report said there was "circumstantial evidence" that person to person transmission has already occurred, based on the belief that a person became sick after being exposed only to an infected person, not a bird.

"It is possible that the avian H5N1 viruses are becoming more infectious for people, facilitating infection in a greater number or range of people, and resulting in more clusters," the report warned. "It is possible that avian H5N1 viruses are becoming more capable of human to human transmission."