Fifty-six of 733 patients in China who were evaluated for suspected Severe Fever with Thrombocytopenia Syndrome (SFTS) were shown by polymerase chain reaction (PCR) to be infected with Candidatus Rickettsia tarasevichiae (CRT). Fever, myalgia, cough, gastrointestinal symptoms, and hemorrhagic manifestations were common. Rash was rarely seen, and eschar was observed in 16% of cases. Thrombocytopenia, leukopenia, and abnormal LFTs were commonly observed. Co-infection with SFTS virus was seen 66% of patients, and eight patients died. [ABSTRACT FROM AUTHOR]