A 72-year-old man was admitted to the emergency ward in our hospital on July 20, 2001, because of consciousness disturbance, fever, generalized skin eruption, and severe general weakness beginning 7 days previously. Physical examination on admission revealed marked systemic cyanosis, erythema, and purpura. Laboratory findings indicated disseminated intravascular coagulation (DIC) and multiorgan failure (platelet count, 0.9 × 104/μl; fibrin degradation product, 110 μg/ml; C-reactive protein, 22.6 mg/dl). Soluble interleukin 2-receptor (sIL-2R) was markedly increased to 14 710 U/ml. Blood gas analysis demonstrated severe metabolic acidosis. He was diagnosed with multiorgan failure due to DIC. Administration of heparin and sodium bicarbonate was started immediately, but respiratory failure was exacerbated and systemic spasm caused by encephalitis was noted. Although he was supported by an artificial ventilator, deterioration of metabolic acidosis occurred, and the blood pressure decreased to less than 60 mm Hg. He died 5.5 h after admission. The serological test showed no positive antibody titers against Orientia
japonica, or Rickettsia
typhi. However, a specific DNA band derived from R.
japonica was detected by the polymerase chain reaction (PCR) method using a primer from a blood clot. Therefore, he was definitively diagnosed as having Japanese spotted fever. The PCR method may be markedly useful for establishing a definitive diagnosis of Japanese spotted fever during the critical stage.