Alaska remains suspected portal for avian influenza
April 6, 2016
by Bob Sims
ANCHORAGE, Alaska – A new report from the US Geological Survey (USGS) announces that western Alaska is still a likely entry point for avian influenza coming into North America.
The new report is entitled, “Surveillance for Eurasian-origin and intercontinental reassortant highly pathogenic influenza A viruses in Alaska, spring and summer 2015” and is published in Virology Journal.
Due to the overlap of North American and Eurasian migratory bird flyways in the western part of the state, Alaska is still an important area to monitor. However, the report also states that no highly pathogenic avian influenza viruses have been found in Alaska.
“Our past research in western Alaska has shown that while we have not detected the highly pathogenic avian influenza virus, up to 70 percent of the other avian influenza viruses isolated in this area were found to contain genetic material from Eurasia, providing evidence for high levels of intercontinental viral exchange,” said Andy Ramey, a scientist with the USGS and lead author of the recent report. “This is because Asian and North American migratory flyways overlap in western Alaska.”
The “highly pathogenic” tag does not refer to how infectious the viruses might be to humans, mammals or other species of birds, but to its potential to cause disease in, or death to chickens. Most strains of avian influenza cause few signs of disease in wild birds that are infected and are not highly pathogenic, but in poultry, some low pathogenic strains can mutate into highly pathogenic strains. These mutated strains cause contagious and severe illness or death in poultry and some wild birds.
USGS research found low pathogenic H9N2 viruses in a Northern Pintail and an Emperor Goose in the past that were almost identical in genetics to those found in wild bird samples from Cheon-su Bay, South Korea, and Lake Dongting, China.
“These H9N2 viruses are low pathogenic and not known to infect humans, but similar viruses have been implicated in disease outbreaks in domestic poultry in Asia,” Ramey said.
Bird samples were obtained from Native Alaskan subsistence hunters in 2015 through collaboration between the USGS, the Southeastern Cooperative Wildlife Disease Study in Athens, Georgia, and the Yukon Kuskokwim Health Corporation in Bethel, Alaska, for the new report. Harvested water birds, the primary hosts of avian influenza viruses, provided 1,000 swabs to researchers through the hunters.
The USGS will use mostly samples from sport hunters this fall to test wild birds at Izembek National Wildlife Refuge in the Southwest Region of the state.