First case of nosocomial transmission of severe fever with thrombocytopenia syndrome in Japan.

We report the first case of human-to-human transmission of severe fever with thrombocytopenia syndrome (SFTS) in Japan. A trainee doctor in his 20s treated a patient with SFTS, who died 3 days after admission. In addition to providing initial care, the doctor also participated in postmortem care. Eleven days after initial contact with the patient, the doctor developed fever, joint pain, diarrhea, and headache, and was subsequently diagnosed with SFTS. Genomic analysis of the SFTS virus (SFTSV) isolated from both the patient and the doctor revealed that they were infected with the same viral strain. These findings strongly suggest that the trainee doctor acquired the infection through nosocomial exposure. The most likely opportunities for transmission were during the initial physical examination or postmortem care. The latter posed a higher risk of infection, as central venous catheter removal and suturing procedures involved exposure to blood, and the trainee doctor did not wear protective goggles during the process. To prevent future human-to-human SFTSV transmission, strict adherence to standard and transmission-based precautions is essential, particularly during procedures where blood exposure is possible, such as during postmortem care.