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
Other diagnostic factors
- abdominal pain
- 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
- residence in or recent exposure to rural area
- recent (within 2 weeks) outdoor exposure
- known antecedent tick bite
- exposure to dogs or pets that spend time outdoors
Diagnostic tests
1st tests to order
- CBC
- serum electrolytes and blood urea nitrogen
- LFTs
- indirect immunofluorescent antibody (IFA)
- blood culture
Tests to consider
- complement fixation
- latex agglutination
- indirect hemagglutination
- microagglutination
- enzyme immunoassay
- lumbar puncture
- chest x-ray
- abdominal CT scan
- immunohistochemistry
- polymerase chain reaction
Treatment algorithm
suspected Rocky Mountain spotted fever (RMSF)
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.
Peer reviewer acknowledgements
BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.
Disclosures
Peer reviewer affiliations and disclosures pertain to the time of the review.
References
Key articles
Biggs HM, Behravesh CB, Bradley KK, et al. Diagnosis and management of tickborne rickettsial diseases: Rocky Mountain spotted fever and other spotted fever group rickettsioses, ehrlichioses, and anaplasmosis - United States. MMWR Recomm Rep. 2016;65:1-44.Full text Abstract
Centers for Disease Control and Prevention. Ticks: tickborne diseases of the United States. Mar 2025 [internet publication].Full text
Reference articles
A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.
Differentials
- Other rickettsial diseases
- Meningococcemia
- Ehrlichiosis
More Differentials指南
- CDC Yellow Book: health information for international travel - rickettsial diseases
- Clinical care of Rocky Mountain spotted fever
More 指南
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