Orientia tsutsugamushi DNA load and genotypes in blood as a marker of severity.

• The numbers of O. tsutsugamushi DNA copies in surviving and non-surviving patients were significantly different (p <0.001). • Our finding demonstrates the relationship between O. tsutsugamushi DNA copy load and fatality in patients with scrub typhus. • Our study demonstrated that the disease severity was associated with the genotypes and bacterial load in patients infected with O. tsutsugamushi. Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi and is endemic to many parts of the Asia-Pacific region. We investigated whether the genotype of O. tsutsugamushi or the DNA load would be a useful marker of disease severity in scrub typhus patients. We evaluated the clinical features, genotypes and bacterial DNA load in the blood of 118 patients, including 114 surviving and 4 non-surviving patients, admitted at Chosun University Hospital. Four patients infected with the Pajoo, Yonchon, Youngworl and Boryong genotypes died. In the 114 survivors, 100 Boryong and 2 Taguchi genotypes were identified. The genotypes involved showed significant differences between the surviving and non-surviving patients (p <0.001). The median number of O. tsutsugamushi DNA copies was 78 copies /μL (range 3,960) in surviving patients, whereas 83,800 copies/μL (range 244,600) in the non-surviving patients. We found that the genotype and DNA load in the patient's blood are useful markers of disease severity in scrub typhus. [ABSTRACT FROM AUTHOR]