Fever of unknown origin due to rickettsioses.

Most common rickettsioses do not fill the criteria for fever of unknown origin, with fever often inferior to lasting less than 1 week. Q fever, scrub typhus, murine typhus, human monocytic ehrlichiosis, and Bartonellosis could fill these criteria, however, notably in uncommon presentations. Moreover, in patients returning from tropical areas or from geographic endemic areas for rickettsiosis, or in patients in contact with animals or ticks, theses etiologies should be kept in mind by physicians challenged to diagnose cause of fever. In this context, even without confirmation of diagnosis, treatment with doxycycline should be used.