Health Officials in Protective Suits Put a Goose Into a Sack as Part of Preventive Measures Against the H7N9 Bird Flu at a Poultry Market in Zhuji, Zhejiang Province
In Photo: Health officials in protective suits put a goose into a sack as part of preventive measures against the H7N9 bird flu at a poultry market in Zhuji, Zhejiang province January 5, 2014. The local government ordered all live poultry be killed at two markets in Zhuji after a 34-year-old woman was confirmed to be infected with the H7N9 virus on Saturday, local media reported. Picture taken January 5, 2014. REUTERS

A new study shows that wild geese may carry bird flu virus on their wings when they migrate. The study uses GPS tracking data of four species of Asian wild fowl and genetic analysis of the virus to suggest that the strain H5N1 travels along migratory flyways.

According to reports in Science News, human outbreaks of the disease coincide with the migration of birds. Since 2003, 676 people have been infected with the virus and 398 have died from it.

Bar-headed geese and ruddy shelducks spend the winter in India, Nepal, Bangladesh and Myanmar before they fly the Central Asian flyway to breed in Mongolia. 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.

H5N1 is a highly pathogenic influenza virus which first emerged in Asia but spread around the world. Recently, cases of influenza virus have been detected in wild fowl in parts of the United States.

The scientists who studied the migration of H5N1 bird flu say that they do not fully understand the long-distance transmission and seasonal patterns of H5N1. In this study, by combining satellite data, outbreak records and genetic study of the virus, the outbreak of H5N1 are shown to be closely associated with known migratory routes.

The spread of the avian influenza virus and its persistence in Asia has led to large-scale economic losses in the poultry sector.

The study shows that within each wild fowl migratory flyway, the timing of H5N1 outbreaks and viral migrations are closely associated, but there was little viral migration observed between flyways. The flyways act as a major viral transmission barrier to the intracontinental spread of the H5N1 bird flu virus within Asia, whereas geographical distances between flyways have little effect on H5N1 transmission.

The study improves our understanding of how wild fowl migration drives the periodic reemergence of H5N1 in Asia.

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