ObjectiveTo investigate the clinical characteristics,epidemiology of patients with severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) infection and genetic sequences of SFTSV.MethodsClinical data of five cases of severe fever with thrombocytopenia syndrome (SFTS)from Zhoushan Hospital during May 2011 to July 2011 were retrospectively analyzed.SFTSV gene was amplified by polymerase chain reaction (PCR).CD3+ CD4+ and CD3+ CD8+T lymphocytes were detected by flow cytometry (FCM).The sequences of isolated SFTSV strains were compared with those in GenBank. ResultsThe symptoms of continuous high fever,sore muscles,enlarged superficial lymph nodes,abdominal pain,diarrhea with gastrointestinal hemorrhage were observed.The white blood cells,platelets and CD3+ CD4+ T lymphocytes were progressive decreased in acute phase with the minimum of (0.97-2.00) × 109/L,(12-42) × 109/L and 7.52％-20.39％,respectively.The SFTSV was isolated from the sera of two patients.The sequences were compared with SFTSV sequences in GenBank.The homology of RNA-dependent RNA polymerase gene was 96％ compared with BX-2010,L-WWG,LN3,JS4,SD4,HN6 and AH12; the glycoprotein gene was 94％ ; N protein gene was 95％ compared with JS4,SD4 and LN4.The homology of the above three genes between two isolates was 99％.ConclusionsOur results suggest that SFTSV is sporadic in Zhejiang Province which is probably from native epidemic focus.SFTS is progressive and severe with acute onset.Multiple organ dysfunction is common in severe eases.