Guest guest Posted July 30, 2009 Report Share Posted July 30, 2009 Scientists fear potent hybrid flu may develop 2009/07/30 BIRD flu kills more than 60 percent of its human victims, but doesn't easily pass from person to person. H1N1, or swine flu, can be spread with a sneeze or handshake, but kills only a small fraction of the people it infects. So what happens if they mix? This is the scenario that has some scientists worried: The two viruses meet – possibly in Asia, where bird flu is endemic – and combine into a new bug that is both highly contagious and lethal and can spread around the world. Scientists are unsure how likely this possibility is, but note that the new swine flu strain – a never-before-seen mixture of pig, human and bird viruses – has shown itself to be especially adept at snatching evolutionarily advantageous genetic material from other flu viruses. " This particular virus seems to have this unique ability to pick up other genes, " said leading virologist Dr Webster, whose team discovered an ancestor of the current flu virus at a North Carolina pig farm in 1998. The current swine flu strain – known as H1N1 – has made more than 2300 people sick in 24 countries. While people can catch bird flu from birds, the bird flu virus – H5N1 – does not easily jump from person to person. It has killed at least 258 people worldwide since it began to ravage poultry stocks in Asia in late 2003. The World Health Organisation has reported two new human cases of bird flu. One patient is recovering in Egypt, while another died in Vietnam – a reminder that the H5N1 virus is far from gone. " Do not drop the ball in monitoring H5N1, " WHO director-general Margaret Chan told a meeting of Asia's top health officials in Bangkok . " We have no idea how H5N1 will behave under the pressure of a pandemic. " Experts have long feared that bird flu could mutate into a form that spreads easily among people. The past three flu pandemics – the 1918 Spanish flu, the 1957-58 Asian flu and the Hong Kong flu of 1968-69 – were all linked to birds, though some scientists believe pigs also played a role in 1918. Webster, who works at St Jude's Children's Research Hospital in Memphis, Tennessee, 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. " My great worry is that when this H1N1 virus gets into the epicentres for H5N1 in Indonesia, Egypt and China, we may have real problems, " he said . " We have to watch what's going on very diligently now. " US Centre for Disease Control and Prevention (CDC) spokesperson Dave Daigle said he could not comment specifically on how concerned the agency was about the scenario Webster described, or what it was doing to study such a possibility. Malik Peiris, a flu expert at Hong Kong University, said the more immediate worry was that swine flu would mix with regular flu viruses, as the flu season was in swing in the southern hemisphere. It was unclear what such a combination would produce. But he said there were indications that that scenario was 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 could 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 had not established itself in pigs – but that could change. " If that were to happen and then these two viruses were both established in pigs in Asia, that would be quite a worrying scenario. " Osterholm, an infectious disease specialist at the University of Minnesota who has advised the US government on flu preparations, said while flu experts were discussing the scenario, he had yet to see specific evidence to cause him to think it would happen. " Everything with influenza is a huge guessing game because nature holds all the rules ... so anything is 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. " 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 had been done at the CDC, mixing bird flu and seasonal human flu, resulting in a weak product, he said. Daigle refused to comment on the prospect of any such experiment. 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. " — Sapa-AP http://www.dispatch.co.za/article.aspx?id=333517 Quote Link to comment Share on other sites More sharing options...
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