Rickettsia rhipicephali was initially described in the 1970s from tick isolates in the southern U.S. The tick Rhipicephalus sanguineus is also the main vector of Rickettsia rickettsii in these regions. Although prevalent in a human-biting vector, human infection has yet to be linked to R. rhipicephali and animal models suggest that this is probably a non-pathogenic species for humans.