Case Report: The relation between the incidence of disseminated intravascular coagulation in scrub typhus cases and its serotype in northeastern Japan

Scrub typhus (ST), also known as tsutsugamushi disease, is a rickettsial disease caused by Orientia tsutsugamushi. ST is widely endemic in Asia, including in Japan. ST can be fatal if the diagnosis is delayed. It has been reported that most fatal cases in northeastern Japan occur in spring and summer. We report an 80-year-old Japanese female case of ST who presented with fever and dyspnea without rash. Upon hospitalization, she was diagnosed with pneumonia with disseminated intravascular coagulation (DIC). Although an eschar was found on her lumbar region, she died from sepsis. Elevated tsutsugamushi antibody of IgM (Karp: 1:2560 dilution) was revealed. The diagnosis of ST was made postmortem. We reviewed 11 patients with ST at our hospital in northeastern Japan. All cases occurred in spring or summer and all showed the Karp strain. The prevalence of DIC was 64% and the mortality was 9.1%. We speculate that the Karp serotype may be prone to DIC, which may result in deteriorated condition. Two cases (18.2%), including the present case, showed no rash. The diagnosis of fatal ST may be difficult because it presents less frequently with rash and because it is accompanied by various complications such as pneumonia. When we see a patient with DIC of unknown cause in northeastern Japan in spring or summer, we should keep ST in mind, even if there is no skin rash.