Severe Japanese Spotted Fever With Disseminated Intravascular Coagulation and a Fatal Outcome: A Case Series of Five Patients.

Japanese spotted fever (JSF), caused by Rickettsia japonica, is an endemic tick-borne disease in Japan that usually responds well to tetracycline therapy. However, delayed diagnosis and treatment can result in serious complications such as disseminated intravascular coagulation (DIC) and death. To identify early markers of severe disease, a case series of five JSF patients (one male patient, four female patients; aged 61-78) treated between 2019 and 2024 was analyzed. All patients presented with fever and erythema; two exhibited eschar. Although empirical tetracycline therapy was administered in every case, initiation was delayed in three patients. Among these, two developed DIC, and one experienced multiple organ failure and died despite intensive treatment. Laboratory findings in the fatal case revealed markedly elevated white blood cell (WBC) and creatine kinase (CK) levels at presentation. Statistical analysis (Kruskal-Wallis test) demonstrated significantly higher WBC (p = 0.023) and CK (p = 0.041) values in the fatal case compared with survivors, while platelet count, C-reactive protein, procalcitonin, and liver enzyme levels showed no significant differences. These findings emphasize the importance of early suspicion and prompt antibiotic therapy for JSF, particularly when patients present with fever, rash (including palms and soles), and eschar. Delay in tetracycline initiation correlated with prolonged hospitalization and poor outcomes. Elevated WBC and CK at admission may represent early prognostic indicators for severe JSF, warranting close monitoring and aggressive management. In summary, delayed treatment and high initial WBC and CK were associated with progression to DIC and death in this series. Rapid diagnosis and immediate tetracycline therapy are essential to prevent severe complications.