The spotted-fever group (SFG) of tick-borne rickettsioses. Included are infections caused by the pathogenic organism Rickettsia rickettsii, which causes Rocky Mountain spotted fever. There are six other pathogenic SFG rickettsial species, five of which (R. conorii, R. sibirica, R. japonica, R. australis, and R. africae ) are most likely to be transmitted by a tick bite. R. akari, which causes rickettsialpox, is transmitted to humans by mouse mites.