Early events following Orientia tsutsugamushi infection. Early events following Orientia tsutsugamushi infection. An initial tropism for dendritic cells (DCs) and monocytes at the inoculation zone induces infection and maturation of these cell populations. Infection of DCs impairs their migration, but this promotes rickettsial dissemination nonetheless. Additionally, DCs secrete proinflammatory cytokines and activate the type I IFN response. Monocyte recruitment occurs, which results in mononuclear cell perivascular infiltration and the activation of several transcriptional programs and pathways ending in the upregulation of proinflammatory genes and of the antiviral response and the recruitment of other cell subsets. In summary, by exploiting immune cells, early infection events may favor rickettsial dissemination and an inflammatory profile in Orientia tsutsugamushi infection. Fabián E. Díaz et al. Clin. Microbiol. Rev. 2018; doi:10.1128/CMR.00076-17