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Rocky Mountain spotted fever

Last reviewed: 5 Oct 2024
Last updated: 24 Apr 2024

Summary

Definition

History and exam

Key diagnostic factors

  • known recent tick exposure or bite
  • triad of fever, rash, and history of tick exposure
  • triad of fever, rash, and headache
  • fever
  • rash
  • headache
  • nausea/vomiting
  • myalgia
  • altered mental status
Full details

Other diagnostic factors

  • abdominal pain
  • residence in or recent exposure to rural area
  • diarrhea
  • conjunctivitis
  • lymphadenopathy
  • peripheral edema
  • meningismus
  • splenomegaly
  • hepatomegaly
  • jaundice
  • seizures
  • shock
  • coma
Full details

Risk factors

  • illness onset in spring or summer
  • returned travelers from an endemic area
  • recent (within 2 weeks) outdoor exposure
  • known antecedent tick bite
  • exposure to dogs or pets that spend time outdoors
Full details

Diagnostic tests

1st tests to order

  • CBC
  • serum electrolytes and blood urea nitrogen
  • LFTs
  • indirect immunofluorescent antibody
  • blood culture
Full details

Tests to consider

  • complement fixation
  • latex agglutination
  • indirect hemagglutination
  • microagglutination
  • enzyme immunoassay
  • lumbar puncture
  • convalescent serology
  • chest x-ray
  • abdominal CT scan
  • immunohistochemistry
  • polymerase chain reaction
Full details

Treatment algorithm

INITIAL

suspected Rocky Mountain spotted fever

Contributors

Authors

Christopher A. Ohl, MD

Professor of Medicine

Section on Infectious Diseases

Wake Forest School of Medicine

Winston-Salem

NC

Disclosures

CAO declares that he has no competing interests.

Acknowledgements

Professor Christopher A. Ohl would like to gratefully acknowledge Dr Steven C. Buckingham, a previous contributor to this topic. SCB is an author of several references cited in this topic. We were made aware that Dr Steven C. Buckingham is now deceased.

Peer reviewers

Mary Anne Jackson, MD

Chief

Section of Pediatric Infectious Diseases

Children's Mercy Hospital and Clinics

Professor of Pediatrics

University of Missouri-Kansas City School of Medicine

Kansas City

MO

Disclosures

MAJ is an author of several references cited in this topic.

  • Rocky Mountain spotted fever images
  • Differentials

    • Other rickettsial diseases
    • Meningococcemia
    • Ehrlichiosis
    More Differentials
  • Guidelines

    • CDC Health information for international travel (the Yellow Book): rickettsial diseases
    • Tickborne diseases of the United States: a reference manual for health care providers
    More Guidelines
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