Alaska is at the overlap for parts of the Asian and North American flyways for migratory birds which scientists say could provide an opportunity for exchange of bird flu viruses which then could lead to the evolution of new strains of viruses that could infect humans.
Scientists at the University of Alaska Fairbanks formed the Avian Influenza Program to study the evolution and assess the prevalence of the many different avian influenza viruses in Alaska, including the highly disease-causing (pathogenic), H5N1 Asian subtype, in migratory birds. Researchers from UAF and collaborators from state, federal and private wildlife and public health agencies obtained cloacal samples from birds in the Minto Flats, Yukon Flats and Yukon Delta National Wildlife Refuges, Copper River Delta and other areas in the state this year.
Of the roughly 4,500 samples collected, 290 have been screened to determine the presence of any of the known subtypes of avian influenza virus. Thirty of the 290 samples tested positive for various bird flu viruses, but none of the viral isolation and subtyping to date has detected H5N1. The sample results will provide early detection for 2005 and baseline data for 2006 and subsequent years, which UAF researchers and others can use for compare to future samples and from which they hope to build predictive models of how the viruses mutate and move in the environment.
"With a virus like H5N1 emerging in an area like Southeast Asia and spreading toward Europe if it doesn't reach Alaska this year, those birds that go back may very well pick it up and bring it to Alaska next year to an environment where that H5N1 might mix with other strains it hasn't seen before," said Jonathan Runstadler, a lead scientist on the project, assistant professor of biology and wildlife at UAF's Institute of Arctic Biology and a veterinarian.
"I think we did a good job for this year in what we set out to do -- getting samples from various parts of the state and from a variety of different species, but there are areas of the state we didn't cover, particular sites and species we could use samples from," Runstadler said.
"We're trying to understand the evolution and prevalence of all avian influenza viruses in wild birds, not just H5N1 -- everybody knows birds are where these viruses come from but no one knows how they get from birds to humans," said George Happ, director of the IDeA Network for Biomedical Research Excellence at UAF, which provided start-up funding for the project. "We want to identify what genetic changes are important when a normally benign virus becomes a pathogen."
The 1918 influenza virus which caused one of history's most deadly epidemics -- an estimated 50 million people died and almost half of those who died were healthy, young adults -- was identified in October 2005 as a bird flu that jumped directly to humans. According to the National Institutes of Health, the virus currently circulating in Asia, a strain of the H5N1 subtype, has acquired five of the 10 gene sequence changes associated with the human-to-human transmission of the 1918 virus.
Alaska's samples are being screened by Jeffrey Taubenberger the scientist who extracted and pieced together the viral genes from a lung-tissue sample obtained from a woman who had died in Brevig Mission, Alaska. When influenza swept through the village in 1918 it killed all but a handful of people. Taubenberger, of the Armed Forces Institute of Pathology, was also a member of one of the two teams of scientists who reported in October 2005 that the 1918 influenza was a bird flu that jumped to people.
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