Objective: To analyze the epidemiological characteristics and field investigation findings of the first human case of H10N3 avian influenza virus infection in northern China, providing a reference for future investigations and management of human cases infected with animal-derived influenza.
Methods: Conduct case-based epidemiological investigations, determine common exposures and close contacts, and perform medical observation. Conduct a source tracing investigation and analysis. Collect samples from cases, common exposures, close contacts, poultry, and the external environment. Detect influenza A virus using real-time fluorescent quantitative RT-PCR. Perform metagenomic sequencing on positive case samples and conduct comparisons.
Result: The case was the first human infection with the avian influenza A(H10N3) virus in northern China, identified through active medical consultation and testing by a third-party laboratory. The patient developed symptoms on April 13, 2025, with no prior history of similar symptoms or exposure to infected cases. The patient had a history of poultry farming. On April 28, metagenomic testing of bronchoalveolar lavage fluid samples confirmed a positive result for the avian influenza A(H10N3) virus. A total of 168 samples were collected from co-exposed individuals, close contacts, poultry, and the external environment, all testing negative for the avian influenza A(H10N3) virus. Metagenomic sequencing analysis revealed high homology with the sequence of the avian influenza A(H10N3) virus case reported in Guangxi Zhuang Autonomous Region, China, in December 2024. No secondary cases emerged after implementing emergency measures such as medical observation of close contacts, harmless disposal of poultry from the affected household, and disinfection of suspected exposure sites. The patient was discharged after full recovery through treatment on May 14.
Conclusion: The source of infection for the first case of human infection with avian influenza A (H10N3) in northern China remains unclear, but no human-to-human transmission has been identified. Enhancing the sensitivity of surveillance for novel animal-derived influenza viruses such as H10N3 and strengthening joint prevention and control measures between health and veterinary departments are crucial for the scientific prevention and control of human infections with animal-derived influenza.

China: One human case of avian influenza A(H10N3) reported from Shaanxi Province