LONDON, June 21 (Reuters) - The world has yet to see a form of the deadly bird flu virus that could spread easily between people and cause a global outbreak - but that doesn't mean it won't happen, scientists said on Thursday.
After studying 15 years of data on bird flu viruses in the wild, researchers said some strains were already part way along the road to acquiring a handful of mutations needed to change into a form that could cause a devastating human pandemic.
"The remaining... mutations could evolve in a single human host, making a virus evolving in nature a potentially serious threat," Derek Smith of Britain's University of Cambridge, who led the research, told reporters.
Currently, bird flu, or H5N1 avian flu, can be transmitted from birds to birds, and birds to humans, but not from humans to humans. When it does pass from birds to humans, it is usually fatal.
Two earlier studies by researchers in the United States and Europe have found that with as few as five mutations, H5N1 flu can become transmissible in the air between mammals, including potentially from person to person.
Their work was highly controversial because they manipulated viruses in the lab to produce the new mutated strains.
MUTATIONS ARE ALREADY OUT THERE
Until now, scientists were not sure whether it was possible these same mutations could evolve in nature.
But Smith's co-researcher Colin Russell said their study, published on Thursday in the journal Science, showed it was.
"Viruses that have two of these mutations are already common in birds, meaning that there are viruses that might have to acquire only three additional mutations in a human to become airborne transmissible," he told reporters.
So far, the H5N1 virus, which was first detected in Hong Kong in 1997, has infected tens of millions of ducks, geese, chickens and other birds. People who have been infected - so far there have been 606, of whom 357 have died - are mostly those who came into close contact with birds.
Last year, teams led by Ron Fouchier at Erasmus Medical Center and by Yoshihiro Kawaoka at the University of Wisconsin managed to create laboratory-enhanced versions of the virus that spread like ordinary flu between mammals.
This type of research is seen as vital for scientists working to develop vaccines, diagnostic tests and anti-viral drugs that could be deployed in the event of an H5N1 pandemic.
But opponents said the work could be misused by terrorists or that the virus might somehow escape from the lab and spread. An international row over the publication of the two papers blew up, leading to a temporary moratorium on such research.
Smith likened scientists' current position on the likelihood of an H5N1 human pandemic to that of researchers trying to predict an earthquake.
"We now know that we're living on a fault line," he said. "And what we have discovered in this working collaboration with Fouchier and Kawaoka is that it's an active fault line. It really could do something. We've seen no fundamental hurdle to that happening."
But he said it was impossible to assess the exact risk. "We know it is in the realms of possibility ... and what needs to be done now is to assess the risk more accurately."
In a second H5N1 study published as part of a series on bird flu in Science on Thursday, Rino Rappuoli, a researcher at the Swiss drugmaker Novartis's vaccines and diagnostics unit in Italy, outlined how the world could better prepare for a potential bird flu pandemic.
Among the most important steps, he said, would be to immunise as many people as possible with existing H5N1 vaccines to prime their immune systems and reduce the severity of illness if a pandemic were to happen. There was also a need to ensure manufacturers could make large quantities of a pandemic vaccine quickly by sharing strains and scientific knowledge swiftly across the world.
Our 2024 Coverage Needs You
It's Another Trump-Biden Showdown — And We Need Your Help
The Future Of Democracy Is At Stake
Our 2024 Coverage Needs You
Your Loyalty Means The World To Us
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Contribute as little as $2 to keep our news free for all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
The 2024 election is heating up, and women's rights, health care, voting rights, and the very future of democracy are all at stake. Donald Trump will face Joe Biden in the most consequential vote of our time. And HuffPost will be there, covering every twist and turn. America's future hangs in the balance. Would you consider contributing to support our journalism and keep it free for all during this critical season?
HuffPost believes news should be accessible to everyone, regardless of their ability to pay for it. We rely on readers like you to help fund our work. Any contribution you can make — even as little as $2 — goes directly toward supporting the impactful journalism that we will continue to produce this year. Thank you for being part of our story.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
It's official: Donald Trump will face Joe Biden this fall in the presidential election. As we face the most consequential presidential election of our time, HuffPost is committed to bringing you up-to-date, accurate news about the 2024 race. While other outlets have retreated behind paywalls, you can trust our news will stay free.
But we can't do it without your help. Reader funding is one of the key ways we support our newsroom. Would you consider making a donation to help fund our news during this critical time? Your contributions are vital to supporting a free press.
Contribute as little as $2 to keep our journalism free and accessible to all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
As Americans head to the polls in 2024, the very future of our country is at stake. At HuffPost, we believe that a free press is critical to creating well-informed voters. That's why our journalism is free for everyone, even though other newsrooms retreat behind expensive paywalls.
Our journalists will continue to cover the twists and turns during this historic presidential election. With your help, we'll bring you hard-hitting investigations, well-researched analysis and timely takes you can't find elsewhere. Reporting in this current political climate is a responsibility we do not take lightly, and we thank you for your support.
Contribute as little as $2 to keep our news free for all.
Can't afford to donate? Support HuffPost by creating a free account and log in while you read.
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. Would you consider becoming a regular HuffPost contributor?
Dear HuffPost Reader
Thank you for your past contribution to HuffPost. We are sincerely grateful for readers like you who help us ensure that we can keep our journalism free for everyone.
The stakes are high this year, and our 2024 coverage could use continued support. If circumstances have changed since you last contributed, we hope you'll consider contributing to HuffPost once more.
Support HuffPostAlready contributed? Log in to hide these messages.