Scrub typhus, caused by the intracellular bacterium Orientia tsutsugamushi, is a major cause of febrile illness in the Asia/Pacific region. Here, we implemented a novel real-time PCR and determined the relation of DNA target gene concentration with serum cytokine levels. The limit of detection of the novel real-time PCR was 1,062 DNA copies per ml of EDTA whole blood. Specificity was excellent as determined on a panel of blood- and skin-borne bacteria, including Rickettsia spp. as well as healthy Vietnamese blood donors. Bacterial DNA concentrations after 9 to 12 days from symptoms onset were significantly higher than in earlier or later periods (P
