Last reviewed: 17 Sep 2021
Last updated: 12 Jan 2021



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
  • diarrhoea
  • conjunctivitis
  • lymphadenopathy
  • peripheral oedema
  • meningismus
  • splenomegaly
  • hepatomegaly
  • jaundice
  • seizures
  • shock
  • coma

Risk factors

  • illness onset in spring or summer
  • returned travellers 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

  • FBC
  • serum electrolytes and urea
  • LFTs
  • indirect immunofluorescent antibody (IFA)
  • blood culture

Investigations to consider

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

Treatment algorithm



Christopher A. Ohl, MD

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 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


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 topic.

Use of this content is subject to our disclaimer