[editing is mine]
Released: 6/27/2013 5:00:00 PM
U.S. Department of the Interior, U.S. Geological Survey
Office of Communications and Publishing
12201 Sunrise Valley Dr, MS 119
Reston, VA 20192
ANCHORAGE, Alaska — Low-pathogenic avian influenza viruses with
Eurasian genes have been found among birds in the Yukon-Kuskokwim Delta
of western Alaska, supporting the theory that the area is a potential
point of entry for foreign animal diseases such as the more highly
pathogenic H5N1 strain, according to a new study by U.S. Geological
The Yukon-Kuskokwim Delta is an important breeding ground for many
bird species and is located where multiple migratory flyways converge,
providing opportunities for avian pathogens to spread. Among these
pathogens are H5N1 avian influenza, which occurs in both low-pathogenic
and the more dangerous highly pathogenic forms.
After the outbreak of the highly pathogenic H5N1 strain of avian
influenza in wild birds of China in 2005, the USGS and the U.S. Fish and
Wildlife Service, in cooperation with the Yukon-Kuskokwim Health
Corporation, the Kawerak Tribal Corporation and other partners,
conducted four years of testing wild migratory birds in western Alaska
for the highly pathogenic H5N1 strain.
In a paper published by the USGS and the USFWS scientists no highly
pathogenic forms of avian influenza were found in more than 24,000
samples tested from 82 species on the Yukon-Kuskokwim Delta from 2006 to
2009, however, 90 low-pathogenic strains of the virus were obtained
from these Alaskan samples. Low-pathogenic avian influenza viruses are
common among wild birds and do not cause mortalities to the degree often
seen with highly pathogenic forms of the virus, said USGS research
geneticist Andrew Reeves, lead author of the paper. The significance of
this study is that it demonstrates that viruses with genes of Eurasian
origin can enter North America via migratory birds.
In addition, researchers discussed how low pathogenic virus samples
from birds further from Asia contained fewer genes attributable to
"This finding supports a 'dilution-by-distance' idea we've
hypothesized in other studies," Reeves said. "Birds sampled further from
Asia, such as in the lower-48 United States, very rarely contain avian
influenza viruses with Eurasian genes, but in Alaska they are more
"Many of the bird samples used in the study were provided by
subsistence hunters in 11 villages throughout the Yukon-Kuskokwim Delta
who collected samples from many species, including ducks, geese, swans
and shorebirds," said Kim Trust of the USFWS.
"Without our partners in western Alaska, we would not have the robust
data set that supports the findings in this paper," Trust said.
Reeves added that the current study provides support for retaining
the Yukon-Kuskokwim Delta as a high-priority region for the surveillance
of potentially harmful avian pathogens.
The paper in the Journal of Wildlife Diseases, "Genomic analysis of avian influenza viruses from waterfowl in western Alaska, USA,"
by Andrew Reeves, John Pearce, Andrew Ramey, Craig Ely, Joel Schmutz,
Paul Flint, Dirk Derksen and Hon Ip of the USGS and Kimberly Trust of
the USFWS, is available online.