RICKETTSIAE
RICKETTSIAE DISEASES INFECTIOUS AGENTS Rickettsial infections are caused by a variety of bacteria from the genera Rickettsia, Orientia, Ehrlichia, Neorickettsia, Neoehrlichia , and Anaplasma ( Table 3-18 ). Rickettsia spp. are classically divided into the typhus group and spotted fever group (SFG). Orientia spp. make up the scrub typhus group. The rickettsial pathogens most likely to be encountered during travel outside the United States include R. africae (African tick-bite fever), R. conorii (Mediterranean spotted fever), R. rickettsii (known as both Rocky Mountain spotted fever and Brazilian spotted fever), O. tsutsugamushi (scrub typhus), and R. typhi (murine typhus). TRANSMISSION Most rickettsial pathogens are transmitted by ectoparasites such as fleas, lice, mites, and ticks. Organisms can be transmitted by bites from these ectopara...