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Top flu expert warns of a swine flu-bird flu mix
(Agencies)
Updated: 2009-05-08 17:16 Webster, who works at St. Jude's Children's Research Hospital in Memphis, Tenn., said bird flu should be a worry now. Bird flu is endemic in parts of Asia and Africa, and cases of swine flu have already been confirmed in South Korea and Hong Kong.
Spokesman Dave Daigle said he could not comment specifically on how concerned the US Centers for Disease Control and Prevention is about the scenario Webster describes, or what it is doing to study such a possibility. Malik Peiris, a flu expert at Hong Kong University, said the more immediate worry is that swine flu will mix with regular flu viruses, as flu season begins in the Southern Hemisphere. It is unclear what such a combination would produce. But he said there are indications that scenario is possible. Peiris noted that the swine flu virus jumped from a farmworker in Canada and infected about 220 pigs. The worker and the pigs recovered, but the incident showed how easily the virus can leap to a different species. "It will get passed back to pigs and then probably go from pigs to humans," Peiris said. "So there would be opportunities for further reassortments to occur with viruses in pigs." He said so far bird flu hasn't established itself in pigs -- but that could change. "H5N1 itself has not got established in pigs," he said. "If that were to happen and then these two viruses were both established in pigs in Asia, that would be quite a worrying scenario." Michael Osterholm, an infectious disease specialist at the University of Minnesota who has advised the US government on flu preparations, said while flu experts are discussing the scenario, he has yet to see specific evidence causing him to think it will happen. "Everything with influenza is a huge guessing game because Mother Nature holds all the rules, and we don't even know what they are, so anything's possible," he said. "We don't have any evidence that this particular reassortment is that much more likely to pick up H5N1 than any other reassortment out there." "We don't have to put these things together," he added. "This is not chocolate and peanut butter running into each other in the dark hallway." But there is in fact discussion of putting them together -- in a high-security laboratory -- to see what a combination would look like, according to Webster. Similar tests have been done at the CDC mixing bird flu and seasonal human flu, resulting in a weak product, he said. Daigle, the CDC spokesman, refused to comment on the prospect of any such experiment. Webster has done groundbreaking work on both swine and bird flus in his 40-year career, and has followed the evolution of the current swine flu strain from a virus that sickened a handful of people who worked with North Carolina hogs into a bug that has spread from person to person around the world. He is closely involved in the global effort to analyze what the virus might do next. It has killed 42 people in Mexico and two in Texas, but so far has not proven very deadly elsewhere, leading to some criticism that the World Health Organization's warnings of a potential pandemic have been overblown. Webster said underestimating the swine flu virus would be a huge mistake. "This H1N1 hasn't been overblown. It's a puppy, it's an infant, and it's growing," he said. "This virus has got the whole human population in the world to breed in -- it's just happened. What we have to do is to watch it, and it may become a wimp and disappear, or it may become nasty."
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