Bird flu developments stoke fears

The appearance of the H5N1 strain of bird flu in Europe, and particularly the outbreak reported last month in Turkey, has heightened already raised concerns about the spread of the virus and its potential to seed the next human pandemic. There are new worries about how the disease appeared to infect birds almost simultaneously in 13 provinces scattered around Turkey and further concerns about why more people seemed to be infected than in any other outbreak since the disease first began infecting humans in 2003. Tempering these concerns is the news that relatively few of the Turkish victims have so far died from the disease compared with the previous outbreaks, in which up to half the human cases proved fatal. Doctors and health officials, worried about the threat of a human pandemic, aren’t even sure if these developments constitute good news or bad. But they do suggest that the H5N1 bird flu is a growing challenge. Researchers last month at the World Influenza Centre of the National Institute for Medical Research in London discovered a mutation in the virus isolated from a Turkish child who died of the disease. Michael Purdue, who is overseeing the response to the avian flu outbreak in Turkey on behalf of the WHO, said the mutation had been spotted before in east Asia — where the disease had killed more than 70 people — in Hong Kong in 2003 and Vietnam in 2005. It was too soon to say what it meant, he believed. The mutation was in a surface protein, haemagglutinin, which the virus uses to attach to the respiratory tract. Purdue said it was “clearly not a constant change” as it had been seen only twice so far. A recent study by a team from the Karolinska Institute in Stockholm working in Vietnam suggested that many more people than previously thought may have been infected with the bird flu virus. They reported that hundreds