An Update on Highly Pathogenic Avian Influenza A(H5N1) Virus, Clade 2.3.4.4b

• Published in: The Journal of infectious diseases Vol. 230; no. 3; pp. 533 - 542
• Main Authors: Webby, Richard J, Uyeki, Timothy M
• Format: Journal Article
• Language: English
• Published: US Oxford University Press 23.09.2024
• Subjects: Animals; Avian flu; Birds - virology; Cattle; Conjunctivitis; Cow's milk; Disease Outbreaks; Humans; Influenza A; Influenza A Virus, H5N1 Subtype - classification; Influenza A Virus, H5N1 Subtype - genetics; Influenza A Virus, H5N1 Subtype - isolation & purification; Influenza A Virus, H5N1 Subtype - pathogenicity; Influenza in Birds - epidemiology; Influenza in Birds - virology; Influenza, Human - epidemiology; Influenza, Human - virology; Marine mammals; Outbreaks; Phylogeny; Poultry; Poultry - virology; Public health; Vigilance; Viruses; H5N1 virus; avian influenza; clade 2.3.4.4b
• DOI: 10.1093/infdis/jiae379
• ISSN: 0022-1899; 1537-6613

Abstract Since the resurgence of highly pathogenic avian influenza (HPAI) A(H5N1) virus, clade 2.3.4.4b, during 2021, these viruses have spread widely among birds worldwide, causing poultry outbreaks and infections of a wide range of terrestrial and marine mammal species. During 2024, HPAI A(H5N1) virus, clade 2.3.4.4b, was detected in dairy cattle for the first time and caused an ongoing multistate outbreak, with high levels of virus documented in raw cow milk. Human infections with clade 2.3.4.4b viruses from exposures to infected poultry or dairy cattle have resulted in a wide spectrum of illness severity, from conjunctivitis or mild respiratory illness to severe and fatal pneumonia in different countries. Vigilance, and stronger global virologic surveillance among birds, poultry, terrestrial and marine mammals, and humans, with virus characterization and rapid data sharing, is needed to inform the threat of clade 2.3.4.4b viruses, as they continue to evolve, to public health.