Pathogenesis of Orientia tsutsugamushi Infection in Humans

Orientia tsutsugamushi organisms are maintained in the nature by their life cycles in both mite vectors and vertebrate hosts. Humans acquire the infection by occupational exposure or during their activities of daily living. The clinical manifestations of scrub typhus are usually mild and self-limited. O.tsutsugamushi has been reported to infect many types of cells belonging or not to immune system. The infection and activation of endothelial cells contribute to the pathophysiology of scrub typhus as reported in rickettsioses. The role of immunity in the resolution of O. tsutsugamushi infection is based on findings obtained with animal models and from patients with scrub typhus. The most commonly used methods for diagnosis of scrub typhus are indirect immunofluorescence assay (IFA) and polymerase chain reaction (PCR), although they require special laboratory facilities and needs some expertise to interpret the results. Doxycycline remains the drug of choice for the treatment of scrub typhus.