|Lee, Dong-hun - Orise Fellow|
|Torchetti, Mia - Animal And Plant Health Inspection Service (APHIS)|
|Hicks, Joseph - University Of Texas|
|Killian, Mary - Animal And Plant Health Inspection Service (APHIS)|
|Bahl, Justin - University Of Texas|
Submitted to: Emerging Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/9/2018
Publication Date: 10/1/2018
Citation: Lee, D., Torchetti, M.K., Hicks, J., Killian, M.L., Bahl, J., Pantin Jackwood, M.J., Swayne, D.E. 2018. Transmission Dynamics of Highly Pathogenic Avian Influenza Virus A(H5Nx) Clade 220.127.116.11, North America, 2014–2015. Emerging Infectious Diseases. 24(10):1840-1848. https://doi.org/10.3201/eid2410.171891.
DOI: https://doi.org/10.3201/eid2410.171891 Interpretive Summary: The H5 high pathogenicity avian influenza virus (HPAIV) caused a deadly outbreak in the United States (U.S.), beginning in late 2014, and affecting over 50 million poultry before eradication in June 2015. The purpose of the study was to determine the origin of the outbreak virus and how it spread within the USA. The virus originated from Asia, and mixed with native North American mild or low pathogenicity avian influenza viruses to produce hybrid H5N1, H5N2, and H5N8 HPAIV. The H5 HPAIV circulated in wild birds along the Pacific flyway, spreading directly into backyard and commercial poultry farms while the hybrid H5N2 initially spread in Midwestern states through introduction from wild birds, but later farm-to-farm spread predominated. This data records the risk of intercontinental spread of a HPAIV into the United States, and the differing roles that the wild migratory birds and farm-to-farm spread had in the outbreak.
Technical Abstract: Eurasia highly pathogenic avian influenza virus (HPAIV) H5 clade 18.104.22.168 emerged in North America at the end of 2014 and caused outbreaks affecting >50 million poultry in the United States before eradication in June 2015. We investigated the underlying ecologic and epidemiologic processes associated with this viral spread by performing a comparative genomic study using 268 full-length genome sequences and data from outbreak investigations. Reassortant HPAIV H5N2 circulated in wild birds along the Pacific flyway before several spillover events transmitting the virus to poultry farms. Our analysis suggests that >3 separate introductions of HPAIV H5N2 into Midwest states occurred during March–June 2015; transmission to Midwest poultry farms from Pacific wild birds occurred ˜1.7–2.4 months before detection. Once established in poultry, the virus rapidly spread between turkey and chicken farms in neighboring states. Enhanced biosecurity is required to prevent the introduction and dissemination of HPAIV across the poultry industry.