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Bird flu outbreaks expected in more countries

作者:郑鲅嗓    发布时间:2019-03-02 05:17:06    

By Shaoni Bhattacharya The deadly H5N1 strain of bird flu is likely to spread to more and more countries, a World Health Organization official warned on Monday. The strain, which has killed over 60 people in southeast Asia, appears to have travelled extensively in the latter half of 2005. It has affected birds in China, Mongolia, Russia, Kazakhstan and most recently reached Europe. “There is no question that we will expect further outbreaks of the avian disease in different countries,” says Michael Ryan, the WHO’s director of the department of epidemic and pandemic alert and response, in Geneva, Switzerland. Tests by the European Union reference laboratory for flu in Weybridge, UK, confirmed on Saturday that the virus affecting birds in Romania was the H5N1 strain, the day after coming to the same conclusion about sick turkeys in Turkey. The strain shows similarities to the 1918 human flu virus – which may have killed 50 million people – and is believed to pose a greater risk of starting a new pandemic than other circulating strains. “It’s important for us to remember that avian influenza and pandemic human influenza are not the same things,” Ryan says, and emphasises that the chances of a person catching bird flu remain “extremely low”. But he told New Scientist that the appearance of the deadly strain in Turkey and Romania does pose an increased risk of a pandemic strain emerging. The spread to more countries “in itself increases the risk of the virus jumping to humans”, he says, although he also points out that millions of birds are affected in Asia, and so the bulk of the risk lies there. It is now believed that the virus has been carried and spread by migratory birds. Previously, it was suspected that infected wild birds might have become too ill to actually migrate, and shed the virus far and wide. Previous outbreaks in Asia could be explained by the movement of domestic poultry by people rather than migration of the birds themselves. Andre Farrar, a spokesman for the UK’s Royal Society for the Protection of Birds, says, for example, that the outbreak in wild migratory birds near Qinghai Lake in China, appears to have come from local birds. And the Russian and Kazakhstan outbreaks occurred along a railway route. “But Turkey and Romania changes things. The outbreaks are entirely consistent in terms of the location and timing of bird migration,” Farrar told New Scientist. The incursions by the virus into Europe are on a “flyway” which runs from Central Russia to Turkey and Eastern Europe, then on to the Middle East and down to East Africa. The outbreak in backyard poultry in eastern Romania “is near to an area supporting large numbers of water birds in the Danube delta”, notes a risk-assessment report by the UK government, published on Saturday. The outbreak in the Balikesir region of northwest Turkey is close to Kus Lake, which also supports significant numbers of water birds. If migratory birds are carrying the virus along their “flyways”, this may mean other continents are at risk. Ryan revealed that WHO had been in talks with North African ministers last week regarding the possible introduction of bird flu into Africa. “The Americas, Africa and the Middle East are very much in our minds,

 

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