Resurgence of Zoonotic H5N1 Avian Influenza in Cambodia: Findings from National and International One Health Surveillance Efforts
A new correspondence published in The New England Journal of Medicine (NEJM) — “Resurgence of Zoonotic Highly Pathogenic Avian Influenza A(H5N1) Virus in Cambodia” (DOI: 10.1056/NEJMc2504302) details sixteen laboratory-confirmed human infections detected between February 2023 and August 2024, primarily among children and adolescents exposed to infected poultry.
The study was jointly conducted by the Virology Unit at Institut Pasteur du Cambodge (IPC), the Hong Kong Pasteur Pole / University of Hong Kong, the Francis Crick Institute in London , the Communicable Disease Control Department of the Ministry of Health, the National Institute of Public Health (NIPH), the National Animal Health and Production Research Institute (NAHPRI) of the Ministry of Agriculture, Forestry and Fisheries, the World Health Organization (WHO), and the Food and Agriculture Organization of the United Nations (FAO).
Cases were detected through Cambodia’s long-standing national influenza surveillance network, which was expanded and strengthened during the COVID-19 pandemic. Genomic sequencing revealed that early infections were caused by the regionally endemic clade 2.3.2.1e H5N1 virus, while later cases involve a novel reassortant strain, a genetic hybrid combining segments from multiple avian influenza lineages. This genotype has since spread across the Greater Mekong Subregion and carries mutations linked to increased replication and virulence in mammals, heightening risks to both public health and the poultry industry.
“This virus continues to evolve in complex and unpredictable ways, ” said Dr. Erik Karlsson Head of the Virology Unit at IPC. “Resurgence of zoonotic spillover underscores the importance of rapid, real-time genomic surveillance and One Health coordination between human, animal, and environmental health sectors.”
This publication highlights the strength of Cambodia’s collaborative approach to infectious disease surveillance and outbreak response, uniting national ministries, IPC, FAO, and WHO and other leading international research institutions.
𝐑𝐞𝐚𝐝 𝐭𝐡𝐞 𝐚𝐫𝐭𝐢𝐜𝐥𝐞 𝐡𝐞𝐫𝐞: