This 1976 transmission electron microscopic (TEM) image depicted a brain capillary from a mouse that had been experimentally infected intravenously with Orientia tsutsugamushi rickettsial micro-organisms. In this revealed pericapillary edema. It also reveals that the capillary lumen was partially occluded by a thrombus, and flanking the thrombus, a hypertrophic endothelial cell containing a number of visible organisms free within its cytoplasm. Formerly known as Rickettsia tsutsugamushi, O. tsutsugamushi is the pathogen responsible for causing the febrile disease known as scrub typhus. The disease is transmitted to humans through the bite of larval trombiculid mites, i.e., chiggers, that had fed on infected rodents.