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Bird flu mutations may make it more contagious, less deadly

By Maggie Fox

Remember bird flu? New studies show you should still worry.

Bird flu is still out there and mutating into dangerous forms, but there’s good news too – the changes that could make it spread more easily could make it less deadly, researchers reported on Thursday.

Flu experts funded by the U.S. government published a long-awaited a study on H5N1 bird flu on Thursday, and some of their findings are sobering. It only takes a handful of mutations for the virus to become airborne and easily transmitted from one animal to another. And a second study shows those mutations not only can easily occur in nature – they have already started to do so.

“We now know that we're living on a fault line,” Derek Smith of Cambridge University in Britain, who worked on one of the studies published in the journal Science, told reporters in a teleconference. “It's an active fault line. It really could – it really could do something.”

Now here’s the reassuring part – the mutations that make the virus pass easily from one animal to another also make it a little less dangerous. Instead of taking root deep in the lungs, causing a hard-to-treat pneumonia, the mutated version of H5N1 likes to live in the upper respiratory tract.

“And so it's less likely to cause pneumonia,” said Ron Fouchier of Erasmus Medical Center in Rotterdam, the Netherlands. And, Fouchier and colleagues reported in Science, drugs used to treat flu worked against the mutant version.

H5N1 bird flu has been circulating on and off since 1998, and it has killed nearly 60 percent of nearly 600 people reported infected, according to the World Health Organization. It mostly kills chickens and rarely infects people, but when it does, little can be done for the victims. Many experts believe H5N1 could be the source of the next big deadly pandemic, like those that struck in 1918, 1957 and 1968.

The last pandemic of a new flu was the H1N1 swine flu in 2009. It wasn’t nearly as deadly as other new flu viruses that cause pandemics, probably because it was a mutated form that included bits and pieces of flu viruses that had been infecting people for decades. That could lead people to believe that flu pandemics aren’t that big a deal. But H5N1 is a completely new virus to the human body – one reason it kills such a high percentage of its human victims.

Luckily, the infection doesn’t spread well from birds to people or from one person to another. But like all versions of the flu virus, it evolves and mutates in several different ways. Scientists have been working for years to figure out just which mutations would give H5N1 the ability to spread easily from one person to another, while also staying deadly. The latest work uses ferrets, which get infected with flu in a way very similar to how people get infected.

The work concerned some experts, and last December a committee called the National Science Advisory Board for Biosecurity asked two teams of researchers to hold off on publishing their findings. The U.S. government also asked all flu researchers to agree to a moratorium on genetically changing flu viruses until ground rules could be agreed on. The worry was that the virus could escape and accidentally cause a pandemic or, worse, that terrorists could somehow get hold of the work and use it to make a biological weapon. But the restrictions caused a furor among researchers, who are used to freely sharing their research.

The biosecurity board agreed earlier this year to let the researchers publish their findings.

“It's our hope that (Thursday’s) publication will help to make the world safer, particularly by stimulating many more scientists and policymakers to focus on preparing defenses,” Bruce Alberts editor-in-chief of Science, told the teleconference.

Some of the conclusions from the batch of studies: governments need to loosen rules for drug companies to make it easier and faster to make vaccines against flu; researchers – most funded by governments – need to keep a closer eye on bird flu around the world to watch for the mutations; and the benefits of flu research far outweigh the risks.

“The reason that we accelerated research on influenza is because there's a real threat,” said Dr. Anthony Fauci, director of the National Institute for Allergy and Infectious Diseases, which paid for the controversial flu studies.

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