Bird flu follows avian flyways

Deadly H5N1 influenza travels with migrating wildfowl

Ruddy shelducks

ON THE WING  Ruddy shelducks (Tadorna ferruginea) and other wild birds may spread the deadly H5N1 virus along their migration routes in Asia.

Courtesy of Chao Zhao

Wild geese may fly with the flu on their wings, new research suggests.

Scientists have suspected that wild birds may spread the H5N1 avian influenza virus, but the evidence has been inconclusive. The new study combines GPS tracking data of four species of wildfowl with genetic analysis of the virus and finds that H5N1 spreads along migratory flyways.

Human outbreaks of the disease also coincide with migration time of the birds, Huaiyu Tian of Beijing Normal University and colleagues report December 22 in the Proceedings of the National Academy of Sciences. Since 2003, 676 people have been infected with the virus and 398 have died.

map of flu spread
FLU WAYS Wild geese and other birds migrate along the same paths year after year. Outbreaks of H5N1 avian influenza tend to occur along these flyways, and follow the movement of the wildfowl. H. Tian et al./PNAS 2014

Bar-headed geese and ruddy shelducks spend the winter in India, Nepal, Bangladesh and Myanmar. Then they fly the Central Asian flyway to breed in Mongolia’s Qinghai Province. Along that route, H5N1 epidemics spread at a rate of 607.26 kilometers per month, close to the birds’ migration speed of 573.19 km per month, the researchers found.

In East Asia, swan geese and northern pintails migrate along at least two flyways, the researchers discovered.

Genetic patterns in the virus matched well with the migratory routes, suggesting that wild birds could be important for spreading H5N1 in Asia. 

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.

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