October 28, 2008

Migratory Birds May Carry Bird Flu Virus

U.S. and Japanese scientists say they've found genetic evidence that wild migratory birds may carry the avian influenza virus between Asia and North America.

Scientists with the U.S. Geological Survey, the U.S. Fish and Wildlife Service and the University of Tokyo said their findings mean migratory birds might be more important carriers of avian influenza viruses from continent to continent than previously thought. The study found genetic evidence for the movement of Asian forms of avian influenza to Alaska by northern pintail ducks.

"Although some previous research has led to speculation that intercontinental transfer of avian influenza viruses from Asia to North America via wild birds is rare, this study challenges that," said Chris Franson, a research wildlife biologist with the USGS National Wildlife Health Center and co-author of the study.

Franson said most previous studies focused on bird species that aren't transcontinental migrants or were from mid-latitude locales in North America -- regions far removed from sources of Asian strains of avian influenza.

The study's findings are detailed in the journal Molecular Ecology.