Highlights • Nonspecific early signs hinder prompt diagnosis of H10N3 infection. • H10N3 human infection remains rare but with high clinical severity. • All patients had bird exposure and developed fever, cough, and dyspnoea. • Diagnosis was confirmed by sequencing; imaging revealed viral pneumonia. Abstract Background Since the first human case of H10N3 Avian Influenza in Jiangsu, China (April 2021), three cases have been reported globally. However, clinical and treatment data remain limited. Therefore, we describe the fourth patient’s epidemiology, clinical manifestations, diagnostics, treatment. Case presentation A 23-year-old woman, previously well , presented on 12 Dec 2024 with fever, dry cough and breathlessness after pig and chicken contact . CT showed bilateral pneumonia . Despite high-flow oxygen and broad-spectrum antibiotics she deteriorated , requiring intubation, lung-protective ventilation and VV-ECMO . Bronchoalveolar lavage isolated H10N3 ...