Rickettsial diseases

Last reviewed: 28 Dec 2022
Last updated: 03 Feb 2021



History and exam

Key diagnostic factors

  • fever >38°C
  • rash
  • eschar
  • lymphadenopathy associated with eschar
More key diagnostic factors

Risk factors

  • exposure to human body lice
  • exposure to rodents (rats and mice) and their fleas
  • tick bites
  • mite bites (Southeast Asia, Oceania, northern Australia)
  • travel to the tropics
  • exposure to natural vegetation, forests, scrub, bush
  • exposure to cat or dog fleas
More risk factors

Diagnostic investigations

1st investigations to order

  • FBC
  • LFTs
  • serum electrolyte levels
  • CRP
  • serology
  • polymerase chain reaction (PCR)
More 1st investigations to order

Investigations to consider

  • chest x-ray
  • trial of doxycycline therapy
  • cell cultures
  • immunohistochemistry
More investigations to consider

Treatment algorithm


suspected or confirmed rickettsial infection: non-allergic to doxycycline: not pregnant or breastfeeding

suspected or confirmed rickettsial infection: doxycycline allergy: not pregnant or breastfeeding

suspected or confirmed rickettsial infection: pregnant or breastfeeding



Christopher A. Ohl, MD

Professor of Medicine

Section on Infectious Diseases

Wake Forest University School of Medicine




CAO declares that he has no competing interests.


Professor Christopher A. Ohl would like to gratefully acknowledge Dr Stephen R. Graves, a previous contributor to this topic.


SRG is the author of a reference cited in this topic.

Peer reviewers

S.A.M. Kularatne, MD, FRCP (Lond)


Department of Medicine

University of Peradeniya


Sri Lanka


SAMK declares that he has no competing interests.

Louis Weiss, MD, MPH

Professor of Medicine and Pathology

Albert Einstein College of Medicine

New York City



LW's laboratory research programme is supported by NIH (NIAID) grants. He performs infectious diseases consultation at Montefiore (Weiler Hospital).

  • Rickettsial diseases images
  • Differentials

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  • Guidelines

    • CDC health information for international travel (the Yellow Book): rickettsial diseases (including spotted fever & typhus fever rickettsioses, scrub typhus, anaplasmosis, and ehrlichioses)
    • Communicable disease control manual: rickettsial diseases and Q fever
    More Guidelines
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