Abstract:

Case 1, a 69-year-old male patient, was admitted to our hospital due to "dizziness, fatigue, nausea, diarrhea, and oral bleeding for 10 d", with a recent history of field farming work. The patient exhibited leukopenia, thrombocytopenia, and clinical manifestations of multi-organ dysfunction, including coagulation dysfunction, liver function abnormalities, gastrointestinal disorders, myocardial injury, and respiratory failure. Bone marrow aspiration smear revealed hemophagocytosis, and out-of-hospital testing for the severe fever with thrombocytopenia syndrome bunyavirus was positive. The patient was diagnosed with severe fever with thrombocytopenia syndrome (SFTS) complicated by hemophagocytic lymphohistiocytosis (HLH). After diagnosis, glucocorticoid combined with ribavirin treatment was initiated. However, the patient still died, which may be related to factors such as delayed medical consultation, advanced age, and poor control of viral replication. Case 2, a 73-year-old male patient, was admitted to our hospital due to "fatigue for 1 week", with a recent history of field farming work. The patient also presented with leukopenia and thrombocytopenia, combined with liver and coagulation function abnormalities. Bone marrow aspiration smear showed hemophagocytosis, and the patient was highly suspected of SFTS with HLH. We empirically initiated preemptive treatment with favipiravir for antiviral therapy, combined with glucocorticoid for anti-inflammation, to early inhibit novel bunyavirus replication and cytokine storm. Subsequent testing reported the severe fever with thrombocytopenia syndrome bunyavirus nucleic acid quantification as 2.69×10³ 50% tissue culture infective dose (TCID₅₀)/mL, confirming the diagnosis of SFTS with HLH. The patient's clinical symptoms and various indicators generally improved. Review of these two similar cases suggests that early empirical preemptive use of favipiravir to control viral replication in clinical practice may improve the treatment and prognosis of patients with SFTS complicated by HLH.

Key words: severe fever with thrombocytopenia syndrome (SFTS), hemophagocytic lymphohistiocytosis (HLH), favipiravir