Emergence and interstate spread of highly pathogenic avian influenza A(H5N1) in dairy cattle in the United States

Authors: NGUYEN, THAO-QUYEN - Iowa State University; HUTTER, CARL - Oak Ridge Institute For Science And Education (ORISE); MARKIN, ALEXEY - Iowa State University; THOMAS, MEGAN - Iowa State University; LANTZ, KRISTINA - Animal And Plant Health Inspection Service (APHIS); KILLIAN, MARY LEA - Animal And Plant Health Inspection Service (APHIS); JANZEN, GARRETT - Oak Ridge Institute For Science And Education (ORISE); VIJENDRAN, SRIRAM - Iowa State University; WAGLE, SANKET - Oak Ridge Institute For Science And Education (ORISE); Inderski, Blake; MAGSTADT, DREW - Iowa State University; LI, GANWU - Iowa State University; DIEL, DIEGO - Cornell University; FRYE, ELISHA - Cornell University; DIMITROV, KIRIL - Texas A&M Veterinary Medical Diagnostic Laboratory; SWINFORD, AMY - Texas A&M Veterinary Medical Diagnostic Laboratory; THOMPSON, ALEXIS - Texas A&M Veterinary Medical Diagnostic Laboratory; SNEVIK, KEVIN - Washington State University; Suarez, David; LARKIN, STEVEN - Animal And Plant Health Inspection Service (APHIS); SCHWABENLANDER, STACEY - Animal And Plant Health Inspection Service (APHIS); AHOLA, SARA - Animal And Plant Health Inspection Service (APHIS); JOHNSON, KAMMY - Animal And Plant Health Inspection Service (APHIS); Baker, Amy; AUSTERMANN, SUELEE - Animal And Plant Health Inspection Service (APHIS); TORCHETTI, MIA - Animal And Plant Health Inspection Service (APHIS); Anderson, Tavis

Submitted to: Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2025
Publication Date: 4/25/2025
Citation: Nguyen, T., Hutter, C., Markin, A., Thomas, M., Lantz, K., Killian, M., Janzen, G.M., Vijendran, S., Wagle, S., Inderski, B.T., Magstadt, D.R., Li, G., Diel, D.G., Frye, E., Dimitrov, K.M., Swinford, A.K., Thompson, A.C., Snevik, K., Suarez, D.L., Lakin, S.M., Schwabenlander, S., Ahola, S.C., Johnson, K.R., Baker, A.L., Austermann, S.R., Torchetti, M.K., Anderson, T.K. 2025. Emergence and interstate spread of highly pathogenic avian influenza A(H5N1) in dairy cattle in the United States. Science. 2025 Apr 25;388(2745):eadq0900. https://doi.org/10.1126/science.adq0900.
DOI: https://doi.org/10.1126/science.adq0900

Interpretive Summary: Highly pathogenic avian influenza (HPAI) viruses cross species barriers and have the potential to cause pandemics. In North America since late 2021, HPAI A(H5N1) viruses from one genetic group have infected wild birds, poultry, and mammals. In March of 2024, there was a detection of these viruses in dairy cattle in Texas. Our epidemiological investigation showed that the infection in cattle occurred after a novel virus emerged in wild bird populations. After transmission and movement of the virus in wild birds, a single bird-to-cattle transmission event occurred. The movement of cattle that had no signs of illness across the United States subsequently introduced the virus to another seven US states. Evolution in cattle, a standard function of all influenza A viruses, resulted in the emergence of low-frequency genetic types within individual animals that were associated with increased transmission efficiency, the ability to infect mammals, and mediated the outcome of infection. Our data demonstrated that continued transmission of H5N1 HPAI within cattle populations increases the risk for infection and subsequent spread and it must be monitored within surveillance programs to minimize its public health risk.

Technical Abstract: Highly pathogenic avian influenza (HPAI) viruses cross species barriers and have the potential to cause pandemics. In North America, HPAI A(H5N1) viruses related to the goose/Guangdong 2.3.4.4b hemagglutinin phylogenetic clade have infected wild birds, poultry, and mammals. Our genomic analysis and epidemiological investigation showed that a novel reassortment event in wild bird populations preceded a single wild bird-to-cattle transmission episode. The movement of cattle has played a role in the spread of the avian influenza viruses within the United States dairy herd. Subsequent evolution in cattle resulted in the emergence of low-frequency variants associated with increased transmission efficiency and host-specificity, and changes in virulence in mammals. Continued transmission of H5N1 HPAI within cattle increases the risk for infection and subsequent spread of the virus within human populations.