Xu X, Subbarao K, Cox NJ, Guo Y. Genetic characterization of the pathogenic influenza A/Goose/Guangdong/1/96 (H5N1) virus: similarity of its hemagglutinin gene to those of H5N1 viruses from the 1997 outbreaks in Hong Kong. Virology. 1999;261:15–9. DOIPubMedGoogle Scholar
Bender C, Hall H, Huang J, Klimov A, Cox N, Hay A, et al. Characterization of the surface proteins of influenza A (H5N1) viruses isolated from humans in 1997–1998. Virology. 1999;254:115–23. DOIPubMedGoogle Scholar
Chan PK. Outbreak of avian influenza A(H5N1) virus infection in Hong Kong in 1997. Clin Infect Dis. 2002;34(Suppl 2):S58–64. DOIPubMedGoogle Scholar
Globig A, Staubach C, Sauter-Louis C, Dietze K, Homeier-Bachmann T, Probst C, et al. Highly pathogenic avian influenza H5N8 clade 2.3.4.4b in Germany in 2016/2017. Front Vet Sci. 2018;4:240. DOIPubMedGoogle Scholar
Guan Y, Smith GJ. The emergence and diversification of panzootic H5N1 influenza viruses. Virus Res. 2013;178:35–43. DOIPubMedGoogle Scholar
Lee D-H, Bertran K, Kwon J-H, Swayne DE. Evolution, global spread, and pathogenicity of highly pathogenic avian influenza H5Nx clade 2.3.4.4. J Vet Sci. 2017;18:269–80. DOIPubMedGoogle Scholar
Xie R, Edwards KM, Wille M, Wei X, Wong S-S, Zanin M, et al. The episodic resurgence of highly pathogenic avian influenza H5 virus. Nature. 2023;622:810–7. DOIPubMedGoogle Scholar
King J, Staubach C, Lüder C, Koethe S, Günther A, Stacker L, et al. Connect to protect: dynamics and genetic connections of highly pathogenic avian influenza outbreaks in poultry from 2016 to 2021 in Germany. Viruses. 2022;14:1849. DOIPubMedGoogle Scholar
Zeng J, Du F, Xiao L, Sun H, Lu L, Lei W, et al. Spatiotemporal genotype replacement of H5N8 avian influenza viruses contributed to H5N1 emergence in 2021/2022 panzootic. J Virol. 2024;98:e0140123. DOIPubMedGoogle Scholar
Ahrens AK, Pohlmann A, Grund C, Harder T, Beer M. Novel genotypes of highly pathogenic avian influenza H5N1 clade 2.3.4.4b viruses, Germany, November 2023. Emerg Infect Dis. 2024;30:1737–9. DOIPubMedGoogle Scholar
Peacock TP, Moncla L, Dudas G, VanInsberghe D, Sukhova K, Lloyd-Smith JO, et al. The global H5N1 influenza panzootic in mammals. Nature. 2025;637:304–13. DOIPubMedGoogle Scholar
Kandeil A, Patton C, Jones JC, Jeevan T, Harrington WN, Trifkovic S, et al. Rapid evolution of A(H5N1) influenza viruses after intercontinental spread to North America. Nat Commun. 2023;14:3082. DOIPubMedGoogle Scholar
Huang P, Sun L, Li J, Wu Q, Rezaei N, Jiang S, et al. Potential cross-species transmission of highly pathogenic avian influenza H5 subtype (HPAI H5) viruses to humans calls for the development of H5-specific and universal influenza vaccines. Cell Discov. 2023;9:58. DOIPubMedGoogle Scholar
Caliendo V, Lewis NS, Pohlmann A, Baillie SR, Banyard AC, Beer M, et al. Transatlantic spread of highly pathogenic avian influenza H5N1 by wild birds from Europe to North America in 2021. Sci Rep. 2022;12:11729. DOIPubMedGoogle Scholar
Mostafa A, Nogales A, Martinez-Sobrido L. Highly pathogenic avian influenza H5N1 in the United States: recent incursions and spillover to cattle. Npj Viruses. 2025;3:54. DOIPubMedGoogle Scholar
Youk S, Torchetti MK, Lantz K, Lenoch JB, Killian ML, Leyson C, et al. H5N1 highly pathogenic avian influenza clade 2.3.4.4b in wild and domestic birds: introductions into the United States and reassortments, December 2021–April 2022. Virology. 2023;587:109860. DOIPubMedGoogle Scholar
US Department of Agriculture Animal and Plant Health Inspection Service. Detections of highly pathogenic avian influenza in wild birds [cited 2026 Jan 19]. https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/wild-birds
US Department of Agriculture Animal and Plant Health Inspection Service. Confirmations of highly pathogenic avian influenza in commercial and backyard flocks [cited 2026 Jan 19]. https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/commercial-backyard-flocks
US Department of Agriculture Animal and Plant Health Inspection Service. Detections of highly pathogenic avian influenza in mammals [cited 2026 Jan 19]. https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/mammals
Caserta LC, Frye EA, Butt SL, Laverack M, Nooruzzaman M, Covaleda LM, et al. Spillover of highly pathogenic avian influenza H5N1 virus to dairy cattle. Nature. 2024;634:669–76. DOIPubMedGoogle Scholar
Halwe NJ, Cool K, Breithaupt A, Schön J, Trujillo JD, Nooruzzaman M, et al. H5N1 clade 2.3.4.4b dynamics in experimentally infected calves and cows. Nature. 2025;637:903–12. DOIPubMedGoogle Scholar
Hu S, Cui J. Cattle H5N1 outbreak in US driven by cow’s “cross-nursing” behaviour: elucidating a novel transmission mechanism. Emerg Microbes Infect. 2025;14:2547736. DOIPubMedGoogle Scholar
Shi J, Kong H, Cui P, Deng G, Zeng X, Jiang Y, et al. H5N1 virus invades the mammary glands of dairy cattle through ‘mouth-to-teat’ transmission. Natl Sci Rev. 2025;12:nwaf262. DOIPubMedGoogle Scholar
Sah R, Srivastava S, Kumar S, Mehta R, Donovan S, Sierra-Carrero L, et al. Concerns on H5N1 avian influenza given the outbreak in U.S. dairy cattle. Lancet Reg Health Am. 2024;35:100785. DOIPubMedGoogle Scholar
Callahan D. Stevens County goat tests positive for same influenza virus affecting poultry. Minnesota Board of Animal Health. March 20, 2024 [cited 2026 Mar 17]. https://www.bah.state.mn.us/news_release/stevens-county-goat-tests-positive-for-same-influenza-virus-affecting-poultry
Rolfes MA, Kniss K, Kirby MK, Garg S, Reinhart K, Davis CT, et al. Human infections with highly pathogenic avian influenza A(H5N1) viruses in the United States from March 2024 to May 2025. Nat Med. 2025;31:3889–98. DOIPubMedGoogle Scholar
US Department of Agriculture National Veterinary Servies Laboratories. Highly pathogenic avian influenza (HPAI) H5N1 detections in alpacas [cited 2026 Mar 17]. https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/mammals/highly-pathogenic-avian
Alexakis L, Fusaro A, Kuiken T, Mirinavičiūtė G, Ståhl K, Staubach C, et al.; European Food Safety Authority. European Centre for Disease Prevention and Control; European Union Reference Laboratory for Avian Influenza. Avian influenza overview March–June 2024. EFSA J. 2024;22:e8930. DOIPubMedGoogle Scholar
Lehman KA, Leibsle SR, Detwiler L, Gaborick C, McCoy-Harrison L, Snekvik K, et al. Detection of highly pathogenic avian influenza A(H5N1) virus 2.3.4.4b in alpacas. J Vet Diagn Invest. 2026;12:10406387251414557. DOIPubMedGoogle Scholar
Aebischer A, Günther A, Piesche R, Wernike K, Murr M, Harder T, et al. Development of a multi-species luciferase-based double-antigen ELISA for the detection of antibodies against influenza A virus H5 clade 2.3.4.4b. J Clin Microbiol. 2026;•••: Epub ahead of print. DOIPubMedGoogle Scholar
Laconi A, Fortin A, Bedendo G, Shibata A, Sakoda Y, Awuni JA, et al. Detection of avian influenza virus: a comparative study of the in silico and in vitro performances of current RT-qPCR assays. Sci Rep. 2020;10:8441. DOIPubMedGoogle Scholar
Experimental Zooprophylactic Institute of the Veneto, European Union Reference Laboratory for Avian Influenza and Newcastle Disease. Detection of type A avian influenza virus by real-time RT-PCR [cited 2026 Mar 17]. https://www.izsvenezie.com/documents/reference-laboratories/avian-influenza/diagnostic-protocols/sop-vir-018.pdf
Wick MR. The hematoxylin and eosin stain in anatomic pathology—an often-neglected focus of quality assurance in the laboratory. Semin Diagn Pathol. 2019;36:303–11. DOIPubMedGoogle Scholar
Animal and Plant Health Agency. Veterinary information sheet: South American camelids 2025 Jan 27 [cited 2026 Jan 29]. https://assets.publishing.service.gov.uk/media/678792c73f1182a1e258a235/APHA_Veterinary_Information_Sheet_-_South_American_Camelids.pdf
Yamnikova SS, Mandler J, Bekh-Ochir ZH, Dachtzeren P, Ludwig S, Lvov DK, et al. A reassortant H1N1 influenza A virus caused fatal epizootics among camels in Mongolia. Virology. 1993;197:558–63. DOIPubMedGoogle Scholar
Yondon M, Heil GL, Burks JP, Zayat B, Waltzek TB, Jamiyan BO, et al. Isolation and characterization of H3N8 equine influenza A virus associated with the 2011 epizootic in Mongolia. Influenza Other Respir Viruses. 2013;7:659–65. DOIPubMedGoogle Scholar
Yin Y, Liu Y, Fen J, Liu K, Qin T, Chen S, et al. Characterization of an H7N9 influenza virus isolated from camels in Inner Mongolia, China. Microbiol Spectr. 2023;11:e0179822. DOIPubMedGoogle Scholar
Chu DKW, Perera RAPM, Ali A, Oladipo JO, Mamo G, So RTY, et al. Influenza A virus infections in dromedary camels, Nigeria and Ethiopia, 2015–2017. Emerg Infect Dis. 2020;26:173–6. DOIPubMedGoogle Scholar
Alpaca Owners Association Inc. Alpacas in the US [cited 2026 Mar 17]. https://www.alpacainfo.com/about/statistics/alpacas-us
Food and Agriculture Organization of the United Nations. FOA: camelids are a livelihood for 200,000 families in the Andean highlands of South America [cited 2026 Mar 17]. https://www.fao.org/americas/news/news-detail/camelidos-medio-subsistencia-altiplanos-andinos/en?com
Uhart MM, Vanstreels RET, Nelson MI, Olivera V, Campagna J, Zavattieri V, et al. Epidemiological data of an influenza A/H5N1 outbreak in elephant seals in Argentina indicates mammal-to-mammal transmission. Nat Commun. 2024;15:9516. DOIPubMedGoogle Scholar
Fang K, Li J, Zhao H, Bahati J, Zhao Z, Song W, et al. Assessing HPAI-H5 transmission risk across wild bird migratory flyways in the United States. Nat Commun. 2026;17:2524. DOIPubMedGoogle Scholar
Pulit-Penaloza JA, Belser JA, Brock N, Kieran TJ, Sun X, Pappas C, et al. Transmission of a human isolate of clade 2.3.4.4b A(H5N1) virus in ferrets. Nature. 2024;636:705–10. DOIPubMedGoogle Scholar
Agüero M, Monne I, Sánchez A, Zecchin B, Fusaro A, Ruano MJ, et al. Highly pathogenic avian influenza A(H5N1) virus infection in farmed minks, Spain, October 2022. Euro Surveill. 2023;28:2300001. DOIPubMedGoogle Scholar
Leguia M, Garcia-Glaessner A, Muñoz-Saavedra B, Juarez D, Barrera P, Calvo-Mac C, et al. Highly pathogenic avian influenza A (H5N1) in marine mammals and seabirds in Peru. Nat Commun. 2023;14:5489. DOIPubMedGoogle Scholar
Man W, Du L, Liu Y, Pang Z, Zhu H, Hong B, et al. Evolution of H5N1 cross-species transmission: adaptive mutations driving avian-to-human infection. Adv Genet (Hoboken). 2026;7:e00051. DOIPubMedGoogle Scholar
Alkie TN, Embury-Hyatt C, Signore AV, Ramos D, Moffat E, Raj S, et al. Dairy cow- and avian-origin clade 2.3.4.4b H5N1 induce severe mastitis in lactating goats and transmission to suckling goats. Cell Rep. 2025;44:116346. DOIPubMedGoogle Scholar






