China’s avian flu outbreak that has killed nine people since March is being driven by at least two closely related viruses, a situation that may make it more difficult to contain in humans and birds, researchers said. The H7N9 flu has shown signs of genetic diversity since the first three patients were diagnosed, said Richard Webby, director of a World Health Organization collaborating center for the virus at St. Jude Children’s Research Hospital in Memphis. It already appears more infectious than the H5N1 strain of bird flu that has been circulating since 2003, infecting 600 people and killing 60 percent of them, he said.
Scientists from around the world are working together to understand the virus because of the potential devastation caused by novel infections. The pandemics of the past century include the 1918 Spanish flu that killed as many as 50 million people and the 2003 SARS outbreak that killed 774.
“This virus might be getting more infectious to humans,” Webby said in a telephone interview. “If this is let spread from where it is now, it will evolve further. That’s what viruses do. If it isn’t contained now, that will almost certainly happen.”
Scientists tracking the H7N9 virus need more information about the ecosystems of birds in China, including those in live markets, feeder farms and wild populations, to better understand and tackle the virus, said Maria Zambon, director of the U.K.’s national influenza center. That will provide a clearer view of how easily H7N9 spreads and how best to control it.
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