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Volume 31, Number 6—June 2025
Research Letter

Avian Influenza A(H5N1) Isolated from Dairy Farm Worker, Michigan

Nicole Brock, Joanna A. Pulit-Penaloza, Jessica A. Belser, Claudia Pappas, Xiangjie Sun, Troy J. Kieran, Hui Zeng, Juan A. De La Cruz, Yasuko Hatta, Han Di, C. Todd Davis, Terrence M. Tumpey, and Taronna R. MainesComments to Author 
Author affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia, USA

Main Article

Figure

Transmission and measurement of airborne avian influenza A(H5N1) virus isolated from dairy farm worker, Michigan. A, B) For DCT and RDT testing, ferrets (n = 12) were intranasally inoculated with 106 PFU A/Michigan/90/2024 virus, isolated from the dairy worker, in 1 mL phosphate-buffered saline and were cohoused with naive ferrets in a DCT model (A) or in adjacent cages with perforated sidewalls permitting airborne virus spread but restricting contact in an RDT model (B). Each bar represents a single animal. C, D) For aerosol transmission testing, ferrets (n = 3) were inoculated intranasally with 6 log10 PFU of MI90 virus and tested daily (C). Orange dots represent viral titers from NW in log10 PFU/mL; limit of detection 10 PFU/mL. Grey bars show average viral M gene RNA load. Error bars indicate SD. Limit of detection was 2.9 log10 RNA copies/mL. D) Aerosol samples were collected daily for 5 dpi by using a BC251 cyclone-based sampler (kindly provided by Dr. William Lindsley, National Institute for Occupational Safety and Health) and the SPOT water condensation sampler (Aerosol Devices, https://aerosoldevices.com), as described previously (8). Orange dots represent log10 PFU/mL per hour. Grey bars show average viral M gene RNA. Error bars indicate SD. Limit of detection was 2.5 log10 RNA copies/h. Ferrets were used for tissue collection on day 5. DCT, direct contact transmission; dpi, days postinoculation; NW, nasal washes; RDT, respiratory droplet transmission.

Figure. Transmission and measurement of airborne avian influenza A(H5N1) virus isolated from dairy farm worker, Michigan. A, B) For DCT and RDT testing, ferrets (n = 12) were intranasally inoculated with 106 PFU A/Michigan/90/2024 virus, isolated from the dairy worker, in 1 mL phosphate-buffered saline and were cohoused with naive ferrets in a DCT model (A) or in adjacent cages with perforated sidewalls permitting airborne virus spread but restricting contact in an RDT model (B). Each bar represents a single animal. C, D) For aerosol transmission testing, ferrets (n = 3) were inoculated intranasally with 6 log10 PFU of MI90 virus and tested daily (C). Orange dots represent viral titers from NW in log10 PFU/mL; limit of detection 10 PFU/mL. Grey bars show average viral M gene RNA load. Error bars indicate SD. Limit of detection was 2.9 log10 RNA copies/mL. D) Aerosol samples were collected daily for 5 dpi by using a BC251 cyclone-based sampler (kindly provided by Dr. William Lindsley, National Institute for Occupational Safety and Health) and the SPOT water condensation sampler (Aerosol Devices, https://aerosoldevices.com), as described previously (8). Orange dots represent log10 PFU/mL per hour. Grey bars show average viral M gene RNA. Error bars indicate SD. Limit of detection was 2.5 log10 RNA copies/h. Ferrets were used for tissue collection on day 5. DCT, direct contact transmission; dpi, days postinoculation; NW, nasal washes; RDT, respiratory droplet transmission.

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References
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