Flu in wild birds sparks fears of mutating virus

The deaths in China of more than 1,000 migratory birds from the influenza strain H5N1 has left experts struggling to square the outbreak with their knowledge of the virus. There are rumours being circulated on the Internet that humansin the region have also fallen victim to the disease - although official sources have so far denied this. Until now only a handful of wild birds are known to have died from the disease. Some experts suggest that the migrant birds areasymptomatic carriers of the virus, or that the small number of deaths was simply the result of picking up the infection from local poultry. The latest outbreak now sparks fears that the virus has mutated.