Walsh & Hoyt: Diseases Caused by Rickettsiaceae

The family Rickettsiaceae comprises a group of obligate intracellular bacteria that normally infect animals but that may occasionally cause disease in humans. Rickettsiae that cause human disease have been identified based on antigenic and intracellular growth characteristics and genetics. Human diseases caused by rickettsiae may be separated into two main types: (a) the spotted-fever group and (b) the typhus group. In addition, a third disorder, acute febrile cerebrovasculitis, also may be caused by rickettsial infection. Most rickettsiae cause systemic disease characterized by vasculitis that in some cases affects the eyes and the central nervous system (CNS); however, both the ocular and CNS manifestations of these diseases vary considerably.