General Information: This strain was isolated from a human in South Africa. Causative agent for Rocky Mountain spotted fever. This genus, like other Rickettsial organisms such as Neorickettsia and Anaplasma, is composed of obligate intracellular pathogens. The latter is composed of two organisms, Rickettsia prowazekii and Rickettsia typhi. The bacteria are transmitted via an insect, usually a tick, to a host organism, in this case humans, where they target endothelial cells and sometimes macrophages. They attach via an adhesin, rickettsial outer membrane protein A, and are internalized where they persist as cytoplasmically free organisms. Transovarial transmission (from mother to offspring) occurs in the invertebrate host. This organism causes Rocky Mountain spotted fever which can cause severe damage to the endothelial layer of major organs, including the lungs, heart, kidneys, and skeletal muscle which can result in death.