Can healthy wild birds carry the HPAI H5N1 virus?
Well over 100,000 healthy wild birds have been tested across South-east Asia in the last two years. Out of 16,000 living wild birds (mainly migratory) tested at the Mai Po Nature Reserve in Hong Kong between 1997 and 2004, none tested positive for HPAI H5N1. Of 850 samples (mainly faecal) from living wild birds tested at Lake Erhel, Mongolia in August 2005 (after an H5N1 outbreak), none was positive. In Eurasia, just 13 apparently healthy wild migrant birds have “tested positive” for HPAI H5N1but doubts have been raised as to whether any of these birds was healthy, or indeed actually carrying HPAI H5N1. In currently uninfected areas, many thousands of migratory waterbirds have recently been tested in Korea, New Zealand, Australia, Alaska and Europe. All were found to be negative for HPAI H5N1. On the other hand, Mallard ducks inoculated in the laboratory with certain high-pathogenicity H5N1 variants showed few clinical symptoms of infection. Tree Sparrows from Henan in China have also
