Severe fever with thrombocytopenia syndrome (SFTS) likely associated with a bite from a Siberian weasel (Mustela sibirica): a case report from China

Abstract Background Severe fever with thrombocytopenia syndrome (SFTS) is a life-threatening tick-borne viral disease with high mortality and limited treatment options. Understanding its transmission routes is essential for effective prevention and control. Case presentation We report a case of a 55-year-old woman from Dalian, Liaoning Province, China, who developed high fever, malaise and diarrhea five days after being bitten by a Siberian weasel ( Mustela sibirica ). A diagnosis of SFTS was made on day 12 after SFTS virus was detected in peripheral blood by metagenomic next-generation sequencing. Despite timely antiviral and supportive treatment, the patient rapidly progressed to multiple organ dysfunction and had a poor prognosis. She had no known exposure to ticks or other animals, raising strong suspicion of SFTSV transmission through the weasel bite. Conclusion This is a case of SFTS potentially associated with a Mustela sibirica bite, suggesting a possible but unconfirmed zoonotic transmission route. These findings highlight the urgent need for surveillance of animal hosts in endemic regions to better understand transmission pathways.