|Lee, Dong-hun - Orise Fellow|
|Torchetti, Mia - Animal And Plant Health Inspection Services (APHIS), National Wildlife Center|
|Killian, Mary Lee - Animal And Plant Health Inspection Services (APHIS), National Wildlife Center|
|Hicks, Joseph - University Of Texas|
|Bahl, Joseph - University Of Texas|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/21/2018
Publication Date: 4/15/2018
Citation: Swayne, D.E., Lee, D., Torchetti, M., Killian, M., Pantin Jackwood, M.J., Hicks, J., Bahl, J. 2018. Variable epidemiology of the three outbreaks of unrelated highly pathogenic avian influenza viruses in the United States, 2014-2017. Abstract book for the 10th International Symposium on Avian Influenza, Brighton, United Kingdom, April 15-18, 2018. Paper No. 22.
Technical Abstract: Three unrelated highly pathogenic avian influenza (HPAI) outbreaks have occurred in the United States (US) during 2014-2017. Late in 2014, Canada reported the first outbreak of an H5N2 reassortment virus between the A/goose/Guangdong/1/1996 (Gs/GD)-lineage H5Nx clade 18.104.22.168A HPAI and North American low pathogenicity avian influenza (LPAI). This report followed closely on the heels of the same H5Nx clade affecting birds in Europe and Asia. The US reported H5N2 and H5N8 Gs/GD lineage viruses in both captive and wild birds shortly thereafter, and lead to the largest avian influenza outbreak in US history. The H5Nx HPAI viruses spread down the Pacific Flyway, and reached the Midwest US. Molecular analysis, supported by epidemiologic findings, suggested that affected farms in the Pacific Flyway, and early during the spread in the Midwest, were largely due to point source introductions from wild birds, while later cases in the Midwest were the result of secondary spread. In mid-January 2016, an outbreak of H7N8 occurred in commercial turkey flocks in Indiana. Data suggested a single introduction of LPAI virus occurred from the wild waterfowl reservoir into turkeys, with secondary spread to other operations. The H7N8 virus mutated to HPAI at one farm; no secondary spread was detected. Both LPAI and HPAI viruses were rapidly eliminated through stamping-out. In March 2017, North American H7N9 LPAI affected broiler breeder farms across 4 states (Alabama, Tennessee, Georgia and Kentucky). This virus was of wholly North American origin, and not related to the Eurasian lineage H7N9 virus. Data suggested several geographically distinct introductions of the H7N9 virus. Mutation to HPAI occurred on one farm with secondary spread to one other; both farms were culled. These events highlight the benefits of a rapid stamping out response, and emphasize the need for improved biosecurity to prevent introduction of H5/H7 LPAI and HPAI viruses.