Rickettsial Diseases (Including Spotted Fever & Typhus Fever Rickettsioses, Scrub Typhus, Anaplasmosis, and Ehrlichioses)

Rickettsial infections are caused by multiple bacteria from the order Rickettsiales and genera Rickettsia, Anaplasma, Ehrlichia, Neorickettsia, Neoehrlichia , and Orientia (Table 4-19). Rickettsia spp. are classically divided into the spotted fever group (SFG) and the typhus group, although more recently these have been classified into as many as 4 groups. Orientia spp. make up the scrub typhus group. The rickettsial pathogens most likely to be encountered during travel outside the United States include Rickettsia africae (African tick-bite fever), R. conorii (Mediterranean spotted fever), Anaplasma phagocytophilum (anaplasmosis), R. rickettsii (known as both Rocky Mountain spotted fever and Brazilian spotted fever), Orientia tsutsugamushi (scrub typhus), and R. typhi (murine typhus).