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Title: Widespread detection of highly pathogenic H5 influenza viruses in wild birds from the Pacific Flyway of the United States

Author
item BEVINS, SARAH - Animal And Plant Health Inspection Services (APHIS), National Wildlife Center
item DUSEK, ROBERT - Us Geological Survey (USGS)
item WHITE, LEANN - Us Geological Survey (USGS)
item GIDLEWSKI, TOM - Animal And Plant Health Inspection Services (APHIS), National Wildlife Center
item BODENSTEIN, BARB - Us Geological Survey (USGS)
item MANSFIELD, KRISTIN - Washington Department Of Agriculture
item DEBRUYN, PAUL - Washington Department Of Fish & Wildlife
item KRAEGE, DONALD - Washington Department Of Fish & Wildlife
item ROWAN, ELLA - Washington Department Of Fish & Wildlife
item GILLIN, COLIN - Oregon Department Of Fish & Wildlife
item THOMAS, BRIAN - Animal And Plant Health Inspection Services (APHIS), National Wildlife Center
item CHANDLER, SHANNON - Animal And Plant Health Inspection Service (APHIS)
item Spackman, Erica

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2016
Publication Date: 7/6/2016
Citation: Bevins, S., Dusek, R., White, L., Gidlewski, T., Bodenstein, B., Mansfield, K., Debruyn, P., Kraege, D., Rowan, E., Gillin, C., Thomas, B., Chandler, S., Spackman, E. 2016. Widespread detection of highly pathogenic H5 influenza viruses in wild birds from the Pacific Flyway of the United States. Scientific Reports. 6:28980. doi:10.1038/srep28980.

Interpretive Summary: The most severe form of avian influenza was carried to the United States by wild birds in late 2014. Once the virus was discovered, surveillance in numerous wild bird species was initiated. Since the virus most likely came to North America through migration routes between Alaska and Siberia, surveillance efforts were focused on the Pacific Flyway, the most western route system in the continental U.S. During the winter and spring of 2015, 4,729 specimens were collected from wild birds and tested for the presence of any influenza using broad tests that detect low and high virulence strains. Samples which were positive for any influenza were then further characterized to determine if a severe strain was present. The severe strain was detected in 1.3% of the samples, which is an unusually high amount. Although detection rates were highest in a few duck species. The high number of positives indicates that North American wild birds do not have immunity to this Asian origin virus, so the virus was able to spread rapidly among wild birds.

Technical Abstract: A novel highly pathogenic avian influenza virus belonging to the H5 clade 2.3.4.4 variant viruses was detected in North America in late 2014. Motivated by the identification of these viruses in domestic poultry in Canada, an intensive study was initiated to conduct highly pathogenic avian influenza surveillance in wild birds in the Pacific Flyway of the United States. A total of 4,729 hunter-harvested wild birds were sampled and 1.3% (n=63) tested positive. Three H5 clade 2.3.4.4 subtypes were isolated from wild birds, H5N2, H5N8, and H5N1, representing the wholly Eurasian lineage H5N8 and two novel reassortant viruses. Testing of 149 additional wild birds during avian morbidity and mortality investigations in Washington yielded 10 (6.7%) additional highly pathogenic avian influenza isolates (H5N8=3 and H5N2=7). The geographically widespread detection of these viruses in apparently healthy wild waterfowl suggest that the H5 clade 2.3.4.4 variant viruses may behave similarly in this taxonomic group whereby many waterfowl species are susceptible to infection but do not demonstrate obvious clinical disease. Despite these findings in wild waterfowl, mortality has been documented for some wild bird species and losses in US domestic poultry during the first half of 2015 were unprecedented.