Bird Flu and Wild Birds

A recent paper in the Proceedings of the National Academy of Sciences is linking transmission of H5N1 avian influenza to the migration of wild birds wintering in China. According to a story about the study in the New Scientist,

"The team found H5N1 in six apparently-healthy migratory ducks at Poyang Lake in Jiangxi province, which borders Guangdong and Hunan, in January and March 2005, before the northward migration. The isolates had all the genes, and certain specific mutations, later found in geese at Qinghai Lake, 1700 kilometres northwest. And this virus, notes Peiris, is very like H5N1 in Turkey.

The team also tested whether the Poyang viruses would make ducks too sick to fly by infecting young mallards. “Most got a bit sick then recovered,” says Webster, and all shed virus for up to a week. “The evidence is now overwhelming that migrating birds can move H5N1 over long distances,” says Peiris. “But they are not the scapegoats for maintaining H5N1 within poultry. There the cause and solution lies within the poultry industry."

The Canadian Press also carries this story. Curiously, the PNAS study that these articles discuss is not found on the PNAS website, so I can't comment on it directly. But these news articles do seem to indicate that the authors, while noting that wild birds may carry the virus, claim that the bigger problem is containing its spread once it gets into the poultry population.