Last reviewed:September 2019
Last updated:August  2018



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

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

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

Diagnostic investigations

1st investigations to order

  • CBC
  • serum electrolytes and blood urea nitrogen (BUN)
  • LFTs
  • indirect immunofluorescent antibody (IFA)
  • blood culture
Full details

Investigations to consider

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

Treatment algorithm


Professor of Medicine

Section on Infectious Diseases

Wake Forest School of Medicine




CAO declares that he has no competing interests.

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

Peer reviewersVIEW ALL


Section of Pediatric Infectious Diseases

Children's Mercy Hospital and Clinics

Professor of Pediatrics

University of Missouri-Kansas City School of Medicine

Kansas City



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

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