LONDON, Oct 17: There is no evidence that the killer H5N1 bird flu virus is progressively mutating to leap the species barrier into humans, but that is no cause for complacency, British scientists said on Monday.

If it does make the leap in large numbers it could spread like wildfire, they added. They were speaking as experts from the Medical Research Council (MRC) prepared to fly to China and Vietnam for visits aimed at boosting global cooperation.

“The mutations are completely random,” John Skehel, director of the MRC’s National Institute for Medical Research, who will lead the team, told a news conference.

“So far there is no particular direction in the mutations in H5N1,” he added.

But Alan Hay, director of the World Influenza Centre, said that if or when it did hit the right mutated form to successfully multiply in humans in large numbers, there would be a pandemic.

“Once it does start to spread, it is likely to spread around the world in a matter of months,” he told the same news conference.

Britain’s chief medical officer, Liam Donaldson, has warned that if a global pandemic did take hold at some point it could result in 50,000 deaths in Britain alone.

The World Health Organisation says the virus could mutate into a form that could kill millions of people around the world and has urged governments to prepare for such a pandemic.

The MRC scientists said Britain was stockpiling anti-viral drugs and cautioned that trials of existing influenza vaccines against H5N1 had proved ineffective.

The H5N1 strain first emerged in Hong Kong in 1997, causing the death or destruction of 1.5 million birds and infecting 18 people, killing six.

It re-emerged in 2003 in South Korea, and has now spread to China, Vietnam, Thailand, Laos, Indonesia, Turkey and Romania. H5N1 has infected 117 people in four countries and killed 60, according to the World Health Organization.

Skehel said the more people the bird virus mutated to infect, the more likely it was that it would find a form that would pass more easily between humans — and that was where the real danger lay.

Hay stressed that the kill rate of the virus, when it did take hold in people, illustrated how dangerous it was and therefore how important it was to nip it in the bud in Asia.

“It is continuing to evolve in the poultry population. We have to monitor it as intensively as possible,” he said.

The MRC mission, which starts on Oct. 23, is aimed at improving joint research on flu, Severe Acute Respiratory Syndrome (SARS) and HIV as well as cancer and neurosciences.

An MRC-hosted meeting on Dec. 7, 8 in London of scientists, politicians and industrialists will discuss the reasons for flu being so easily transmissible and the development of vaccines and drugs to control the spread of viruses.—Reuters