The clinical course of 239 cases of Japanese spotted fever in Ise Red Cross Hospital, 2006–2019

Introduction Although the mortality rates associated with Japanese spotted fever (JSF) are unknown, advances in testing technology have led to an increase in JSF-induced mortality reported in clinical practice. Up-to-date clinical information is essential for accurate diagnosis and prompt treatment of JSF. Methods This retrospective descriptive study included patients with JSF who were treated at the Ise Red Cross Hospital between 2006 and 2019. Diagnostic criteria included positive results of molecular-based tests during the acute phase and/or increased serum-specific antibody titers. This study was performed based on the clinical findings, clinical course, treatment, and prognosis in confirmed cases of JSF. Results We investigated 239 patients with a confirmed diagnosis of JSF (48.1% men, mean age 69.2 years). Notably, 237 patients received tetracycline antibiotics, and eight patients died (one patient was misdiagnosed and died without adequate treatment). Four of the remaining patients had a multi-organ failure at the time of admission. However, among the 155 consecutive patients who received effective antibiotic therapy after 2012, we observed two deaths; one patient died of hemorrhage secondary to non-steroidal anti-inflammatory drug-induced duodenal ulcer. Conclusions Our study showed a case fatality rate of 3.3%, which indicates that JSF is a severe illness. Although a few cases of the fulminant disease are reported, early initiation of therapy was shown to improve JSF-induced mortality by approximately 1%. Prompt initiation of antibiotic therapy (even in the absence of genetic test results) is warranted in cases of suspected JSF.