Avian Flu in Geese Signals a Possible Route to Europe

An outbreak of bird flu among migrating geese in western China has opened a potential pathway for the disease to spread to India and Europe, according to studies published online Wednesday by the journals Science and Nature.

The sick birds were discovered April 30 at Qinghai Lake, a breeding hub for bar-headed geese that migrate to Siberia, Myanmar, Australia, New Zealand and over the Himalayas into India -- a possible jumping-off point for transmission of the virus to Europe.

The movement of the H5N1 avian virus beyond its current center in East and Southeast Asia would pose a threat to poultry industries and increase the risk of more infections in humans.

But Chinese researchers said the outbreak, which has killed nearly 2,000 birds, might burn itself out before major seasonal bird migrations begin in September.

“It’s an acute infection. Most of the birds died,” said George F. Gao, director of the Institute of Microbiology in Beijing and chief author of the Science study. “If they all die, the virus may die off with them.”

Scientists have long known that wild waterfowl can contract bird flu and pass it on to farm poultry. But they had believed that the wild animals were infected by mingling with the sick farm birds.

The two new studies show that the virus can also pass between migratory birds, said Malik Peiris, a University of Hong Kong virologist and coauthor of the Nature study.

Qinghai Lake, China’s largest saltwater lake, plays a central role in the life cycle of birds that annually travel thousands of miles.

Migratory birds, such as the bar-headed goose, spend summer months feeding and mating at Qinghai before heading to Southeast Asia and other places for the winter.

Birds that migrate toward India intersect with those on paths to Europe.

Until now, the H5N1 virus had not been detected in bird species that migrate beyond the Far East.

“The area where the virus is circulating now is so big already that you cannot imagine that it will not be spread gradually by migratory birds or other means,” said Jan de Jong, a senior investigator at Erasmus University in the Netherlands.

The current bird flu has been circulating in Asia since 1997 and has killed or led to the culling of about 120 million birds. It has caused 61 human fatalities in Hong Kong, Thailand, Vietnam and Cambodia.

So far nearly all of the human cases have been traced to direct contact with infected birds, but World Health Organization officials warn that if the bird virus recombines with a human virus, the new form could easily pass between people.

They have urged authorities in areas along migration paths to watch flocks for signs of the disease.