Abstract: Objective To summarize the clinical characteristics, prognosis and related factors affecting mortality of severe SFTS patients caused by new bunyaviridae. Methods Clinical data of 23 SFTS patients admitted to the Department of Critical Care Medicine of our hospital from August 2014 to September 2019 were collected, including epidemiological data, symptoms, signs, and the results of auxiliary examinations. According to the outcome of patients, patients were divided into two groups: survival group and death group. The differences of epidemiological data, symptoms, signs, and laboratory test indexes between the two groups were compared. Results All patients had fever, 23 cases had poor appetite, 14 cases had nausea and vomiting, 12 cases had cough and sputum, 16 cases had diarrhea and 12 cases had hemorrhage. There were 14 cases of nervous system changes, 14 cases had different degrees of consciousness disorder and bulbar conjunctival edema, 4 cases had blurred speech, 3 cases had convulsions of whole body or part of limbs, and 2 cases had positive pathological features. Eight patients died and 15 patients were discharged from hospital or transferred in the general ward for treatment. Comparing the clinical data and laboratory examinations of patients in death group and survival group, it was found that the proportion of neurological symptoms in patients that died was significantly higher than that in patients that survived (P<0.05). The viral load of the dead patients was higher and the average BNP was higher than that of the survived patients (P<0.05). The average age of the dead patients was older than that of the improved patients (P<0.05). Conclusion The mortality rate of severe SFTS patients is high. Age, neurological symptoms, poor cardiac function and poor coagulation function are important prognostic indicators. Viral load can effectively monitor the severity of the disease and predict the prognosis.

Key words: Fever with thrombocytopenia syndrome, Clinical features, Prognostic factors