Rickettsia massiliae was first isolated from a tick in Sicily in 1985 and finally identified in 2005. The first human case was not described until 2006, 21 years after the original isolate. This was soon followed by the findings of closely related strains in Rhipicephalus sanguineus both in the southwestern United States and in Argentina, far from the region of its original description. Several species of Rhipicephalus ticks have been detected with R. massiliae infection, extending the range where R. massiliae may be suspected, and requiring better species distinction in diagnostic methods within the regions where either R. rickettsii or R. conorii is carried by the same tick vector.