Large Bird Flu ClusterEmerges
A team of experts from the World Heath Organization (WHO) is making its way north in Pakistan to investigate a cluster of at least eight cases of avian flu in people living near the Afghan border. They will be seeking to establish whether the disease is spreading, and whether the cases were caused by human-to-human transmission.
Cases of bird flu continue to occur worldwide. But this latest outbreak is worrying in that it involves the largest group of closely related cases since a cluster of eight infected people was reported in Indonesia in May 2006.
The Pakistan cases started in mid-November, or possibly earlier, when five family members fell ill in Abbottabad, north of Islamabad. Two of the brothers have died, one of whom was buried before he could be tested for H5N1. In December, a man and his niece in the same town were found to have H5N1. They are thought to have worked on the same farm as the first family affected. Another man was found to have H5N1 in a nearby town some distance from there. Another case is suspected but not yet confirmed, which would bring the cluster to nine.
The WHO team will be tracking individuals who came into contact with the infected cases and testing and/or treating individuals where appropriate. Monitoring for cases in the area will be key to establishing whether the virus has become more virulent or shows signs of spreading. According to a spokesman for WHO, human-to-human transmission cannot be ruled out, as it has occurred on a limited basis on several occasions in the past. Tests of 40 people who have had contact with the patients have so far all turned up negative. Genetic sequencing will help to pin down the mode of transmission and whether any important genetic changes have occurred in the virus.