Mutations in the H5N1 bird flu virus are seemingly making it more deadly in chickens and more resistant in the environment but without yet increasing the threat to humans, the World Health Organisation said on Monday according to Reuters. The changes, which all viruses undergo, have affected patterns of transmission amongst domestic poultry and wild birds, with ducks, for example, developing the ability to pass the virus on without getting ill. "They have not, however, had any discernible impact on the disease in humans, including its modes of transmission," the United Nations' health agency said in a statement posted on its Web site (www.who.int). The virus, which has spread in recent months from Asia into Russia, Africa and western Europe, has so far killed more than 90 people and forced the slaughter of millions of birds as health authorities attempt to stem it. With Western Europe on high alert -- Germany, Austria, France and Italy are amongst states to report cases recently in wild birds -- the WHO said the spread was cause for concern. "The recent appearance of the virus in birds in a rapidly growing number of countries is of public health concern," it said. "It expands opportunities for human exposures and infections to occur." The danger was greatest when the virus jumped from wild to domestic birds, which was easiest when poultry lived in close contact with humans, as in Africa and parts of Asia. --more 21 43 Local Time 18 43 GMT
