Epidemiological and genetic investigation of a cluster of cases of severe fever with thrombocytopenia syndrome bunyavirus

Background To analyze and discuss the transmission route of a cluster of cases of severe fever with thrombocytopenia syndrome bunyavirus (SFTSV). Method We performed an epidemiological investigation and a genetic analysis of patients with severe fever with thrombocytopenia syndrome (SFTS) caused by SFTSV, their close contacts and the surrounding population. Results We found that all patients had contact with the blood of the first patient. The comparison of gene sequences in the three isolated SFTSV strains showed that the strains were closely related. Six close contacts and nine individuals in the surrounding population were positive for SFTSV IgM antibody. Conclusion We suspect that the cluster outbreak was transmitted via blood and that the natural reservoir host of SFTSV exists in the patients’ environment.