H5N1 Clade 2.3.4.4b: Evolution, Global Spread, and Host Range Expansion
Abstract
1. Emergence of 2.3.4.4b Clade Highly Pathogenic Avian Influenza Viruses (HPAIVs)
2. Global Spread of H5N1 HPAIV Clade 2.3.4.4b Since 2020
2.1. Europe
2.2. North and South America
2.3. Sub-Antarctic and Antarctic Region
2.4. Australia
3. H5N1 HPAIV Spillover to Mammals
3.1. Avian Influenza in Cattle and Small Ruminants
3.2. Avian Influenza in Seals and Fur Animals
3.3. Avian Influenza in Companion Animals
4. Human Cases of H5N1 Infection: Overview and Recent Developments
4.1. Cumulative Global Cases and Fatality
4.2. Recent Human Cases (2022–2025)
4.3. Paradigm Shift: Mammal-to-Human Transmission
5. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Chrzastek, K.; Lieber, C.M.; Plemper, R.K. H5N1 Clade 2.3.4.4b: Evolution, Global Spread, and Host Range Expansion. Pathogens 2025, 14, 929. https://doi.org/10.3390/pathogens14090929
Chrzastek K, Lieber CM, Plemper RK. H5N1 Clade 2.3.4.4b: Evolution, Global Spread, and Host Range Expansion. Pathogens. 2025; 14(9):929. https://doi.org/10.3390/pathogens14090929
Chicago/Turabian StyleChrzastek, Klaudia, Carolin M. Lieber, and Richard K. Plemper. 2025. "H5N1 Clade 2.3.4.4b: Evolution, Global Spread, and Host Range Expansion" Pathogens 14, no. 9: 929. https://doi.org/10.3390/pathogens14090929
APA StyleChrzastek, K., Lieber, C. M., & Plemper, R. K. (2025). H5N1 Clade 2.3.4.4b: Evolution, Global Spread, and Host Range Expansion. Pathogens, 14(9), 929. https://doi.org/10.3390/pathogens14090929