Global Biodefense Unusual spike in human infections highlights ongoing risks at the human-animal interface and the need for cross-sectoral public health action. Between January and July 2025, Cambodian health authorities reported 11 laboratory-confirmed cases of human infection with avian influenza A(H5N1), including six fatalities. Notably, seven of these cases occurred in June alone—an unusual monthly spike. These recent infections are part of a broader resurgence that began in February 2023, after nearly a decade without reported human cases in the country. Since that re-emergence, Cambodia has confirmed 27 human infections, with a case fatality ratio (CFR) of 44%.
The recurrence of H5N1 in humans underscores persistent vulnerabilities at the human-animal interface and raises critical concerns about surveillance, biosecurity, and pandemic preparedness in regions where the virus remains endemic in animal populations.