BBC news says the latest scientific evidence suggests that the bird flu virus could mutate to a form that could pass from human to human and trigger a pandemic.

Outbreaks of the potentially deadly virus have so far have emerged through the flu spreading from animals to humans.

However, Nancy Cox, of the U.S. Center for Disease Control and Prevention, says a number of viral subtypes have proven their ability to jump the species barrier.

She said the recent spurt of human infections increases the likelihood that a mutant strain would arise that could spread between humans. She also said the H5N1 strain, which has killed 42 people in Asia since 1997, was one of many such candidates.