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Rocky Mountain Spotted Fever Differential Diagnoses

  • Author: Burke A Cunha, MD; Chief Editor: Michael Stuart Bronze, MD  more...
 
Updated: Oct 08, 2015
 
 

Diagnostic Considerations

The early phase of Rocky Mountain spotted fever (RMSF) is characterized by nonspecific symptoms that may mimic any number of other viral or bacterial infections. This delays proper therapy and contributes to higher mortality.[15]

Human ehrlichiosis caused by Ehrlichia canis mimics RMSF in its clinical manifestations and geographic and seasonal distribution. Rash is not present with ehrlichiosis, so spotless RMSF is usually ehrlichiosis. Doxycycline is the preferred drug for human ehrlichiosis.

If RMSF is treated with antibiotics aimed at another pathogen, the characteristic rash in RMSF may be mistaken for a drug eruption.

Conditions to consider in the differential diagnosis of RMSF include the following:

  • Meningitis
  • Meningococcemia
  • Q Fever
  • Rickettsialpox
  • Streptococcus group A infections
  • Streptococcus group B infections
  • Streptococcus group D infections
  • Syphilis
  • Thrombotic thrombocytopenic purpura
  • Toxic shock syndrome
  • Tularemia
  • Typhus
  • Bronchitis
  • Gastroenteritis
  • Hepatitis
  • Idiopathic thrombocytopenic purpura
  • Meningitis
  • Mononucleosis
  • Henoch-Schönlein purpura
  • Kawasaki disease
  • Measles
  • Rubella
  • Bacterial pneumonia
  • Immunocompromised pneumonia
  • Mycoplasma pneumonia
  • Viral pneumonia
  • Syphilis
  • Thrombocytopenic purpura
  • Ehrlichiosis
  • Lyme disease
  • Q fever
  • Relapsing fever
  • Tularemia
  • Toxic shock syndrome
  • Branch retinal artery occlusion
  • Branch retinal vein occlusion
  • Central retinal artery occlusion
  • Central retinal vein occlusion
  • Acute hemorrhagic conjunctivitis
  • Viral conjunctivitis
  • Eales disease
  • Diffuse unilateral subacute neuroretinitis
  • Ocular ischemic syndrome
  • Optic neuritis
  • Papilledema
  • Red eye evaluation
  • Anterior uveitis
  • Acute surgical abdomen
  • Allergic vasculitis
  • Brill-Zinsser disease
  • Drug hypersensitivity
  • Atypical measles
  • Murine typhus
  • Rubeola
  • Undifferentiated viral illness
  • Drug reactions
  • Other acute rickettsial infections - Eg, Mediterranean spotted fever, North Asian tick typhus, Siberian tick typhus, Astrakhan fever, African tick bite fever, Japanese spotted fever, Queensland tick typhus, Flinders Island spotted fever, Israeli tick typhus, Marseilles tick bite fever
  • Influenza
  • Typhoid fever
  • Disseminated gonococcal infection
  • Drug hypersensitivity
  • Immune complex vasculitis
  • Staphylococcal sepsis
  • Recrudescent typhus
  • Luetic exanthem

Differential Diagnoses

 
 
Contributor Information and Disclosures
Author

Burke A Cunha, MD Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital

Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Coauthor(s)

Marie Spevak O'Brien, DO Assistant Clinical Professor of Medicine, Arthritis and Rheumatology, Lehigh Valley Physician Group

Marie Spevak O'Brien, DO is a member of the following medical societies: American College of Physicians, American College of Rheumatology, American Medical Association, American Osteopathic Association, International Society for Clinical Densitometry, Pennsylvania Medical Society

Disclosure: Nothing to disclose.

Chief Editor

Michael Stuart Bronze, MD David Ross Boyd Professor and Chairman, Department of Medicine, Stewart G Wolf Endowed Chair in Internal Medicine, Department of Medicine, University of Oklahoma Health Science Center; Master of the American College of Physicians; Fellow, Infectious Diseases Society of America

Michael Stuart Bronze, MD is a member of the following medical societies: Alpha Omega Alpha, American Medical Association, Oklahoma State Medical Association, Southern Society for Clinical Investigation, Association of Professors of Medicine, American College of Physicians, Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Acknowledgements

Allon Amitai, MD International Emergency Medicine Fellow, Rhode Island Hospital; Consulting Staff, Memorial Hospital of Rhode Island; Doctoring Preceptor, Brown University Medical School

Allon Amitai, MD is a member of the following medical societies: American College of Emergency Physicians

Disclosure: Nothing to disclose.

David F Butler, MD Professor of Dermatology, Texas A&M University College of Medicine; Chair, Department of Dermatology, Director, Dermatology Residency Training Program, Scott and White Clinic, Northside Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, American Society for MOHS Surgery, Association of Military Dermatologists, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Peter MC DeBlieux, MD Professor of Clinical Medicine and Pediatrics, Section of Pulmonary and Critical Care Medicine, Program Director, Department of Emergency Medicine, Louisiana State University School of Medicine in New Orleans

Peter MC DeBlieux, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, Radiological Society of North America, and Society of Critical Care Medicine

Disclosure: Nothing to disclose.

Dirk M Elston, MD Director, Ackerman Academy of Dermatopathology, New York

Dirk M Elston, MD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

Aaron Glatt, MD Professor of Clinical Medicine, New York Medical College; President and CEO, Former Chief Medical Officer, Departments of Medicine and Infectious Diseases, St Joseph Hospital (formerly New Island Hospital)

Aaron Glatt, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physician Executives, American College of Physicians, American College of Physicians-American Society of Internal Medicine, American Medical Association, American Society for Microbiology, American Thoracic Society, American Venereal Disease Association, Infectious Diseases Society of America, International AIDS Society, and Society forHealthcareEpidemiology of America

Disclosure: Nothing to disclose.

Gary L Gorby, MD Associate Professor, Departments of Internal Medicine and Medical Microbiology and Immunology, Division of Infectious Diseases, Creighton University School of Medicine; Associate Professor of Medicine, University of Nebraska Medical Center; Associate Chair, Omaha Veterans Affairs Medical Center

Gary L Gorby, MD is a member of the following medical societies: Alpha Omega Alpha, American Medical Association, American Society for Microbiology, Infectious Diseases Society of America, and New York Academy of Sciences

Disclosure: Nothing to disclose.

Jon Mark Hirshon, MD, MPH Associate Professor, Department of Emergency Medicine, University of Maryland School of Medicine

Jon Mark Hirshon, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Public Health Association, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Christopher D Johnson, MD Clinical Assistant Instructor, Department of Emergency Medicine, State University of New York Downstate Medical Center College of Medicine

Disclosure: Nothing to disclose.

Rajendra Kapila, MD, MBBS Associate Professor, Department of Medicine, University of Medicine and Dentistry of New Jersey-New Jersey Medical School

Rajendra Kapila, MD, MBBS is a member of the following medical societies: American College of Physicians, American Medical Association, Infectious Diseases Society of America, and Infectious Diseases Society of New Jersey

Disclosure: Nothing to disclose.

Nicole L Lacz, MD Chief Resident, Department of Radiology, St Barnabas Medical Center

Nicole L Lacz, MD is a member of the following medical societies: Alpha Omega Alpha, Phi Beta Kappa, and Sigma Xi

Disclosure: Nothing to disclose.

Byron L Lam, MD Professor, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami School of Medicine

Byron L Lam, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Ophthalmology, American Medical Association, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Simon K Law, MD, PharmD Associate Professor of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, David Geffen School of Medicine

Simon K Law, MD, PharmD is a member of the following medical societies: American Academy of Ophthalmology, American Glaucoma Society, and Association for Research in Vision and Ophthalmology

Disclosure: Nothing to disclose.

Richard Medlin, Jr, MD Consulting Staff, Department of Anesthesiology, Emory University Hospital

Richard Medlin, Jr, MD is a member of the following medical societies: American College of Emergency Physicians and American Medical Association

Disclosure: Nothing to disclose.

Jeffrey Meffert, MD Assistant Clinical Professor of Dermatology, University of Texas School of Medicine at San Antonio

Jeffrey Meffert, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, Association of Military Dermatologists, and Texas Dermatological Society

Disclosure: Nothing to disclose.

Hampton Roy Sr, MD Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences

Hampton Roy Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and Pan-American Association of Ophthalmology

Disclosure: Nothing to disclose.

Noah S Scheinfeld, MD, JD, FAAD Assistant Clinical Professor, Department of Dermatology, Columbia University College of Physicians and Surgeons; Consulting Staff, Department of Dermatology, St Luke's Roosevelt Hospital Center, Beth Israel Medical Center, and New York Eye and Ear Infirmary; Private Practice

Noah S Scheinfeld, MD, JD, FAAD is a member of the following medical societies: American Academy of Dermatology

Disclosure: Optigenex Consulting fee Independent contractor

Robert A Schwartz, MD, MPH Professor and Head, Dermatology, Professor of Pathology, Pediatrics, Medicine, and Preventive Medicine and Community Health, University of Medicine and Dentistry of New Jersey-New Jersey Medical School

Robert A Schwartz, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American College of Physicians, and Sigma Xi

Disclosure: Nothing to disclose.

John D Sheppard Jr, MD, MMSc Professor of Ophthalmology, Microbiology and Molecular Biology, Clinical Director, Thomas R Lee Center for Ocular Pharmacology, Ophthalmology Residency Research Program Director, Eastern Virginia Medical School; President, Virginia Eye Consultants

John D Sheppard Jr, MD, MMSc is a member of the following medical societies: American Academy of Ophthalmology, American Society for Microbiology, American Society of Cataract and Refractive Surgery, American Uveitis Society, and Association for Research in Vision and Ophthalmology

Disclosure: Nothing to disclose.

Richard H Sinert, DO Associate Professor of Emergency Medicine, Clinical Assistant Professor of Medicine, Research Director, State University of New York College of Medicine; Consulting Staff, Department of Emergency Medicine, Kings County Hospital Center

Richard H Sinert, DO is a member of the following medical societies: American College of Physicians and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Richard H Snyder, MD Vice-Chair, Program Director, Department of Medicine, Norfolk General Hospital; Clinical Associate Professor, Department of Internal Medicine, East Virginia Medical School

Richard H Snyder, MD is a member of the following medical societies: American College of Physicians

Disclosure: Nothing to disclose.

Marie Spevak O'Brien, DO Assistant Clinical Professor of Medicine, Arthritis and Rheumatology, Lehigh Valley Physician Group

Marie Spevak O'Brien, DO is a member of the following medical societies: American College of Physicians, American College of Rheumatology, American Medical Association, American Osteopathic Association, International Society for Clinical Densitometry, and Pennsylvania Medical Society

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

R Christopher Walton, MD Professor, Director of Uveitis and Ocular Inflammatory Disease Service, Department of Ophthalmology, Assistant Dean for Graduate Medical Education, University of Tennessee College of Medicine; Consulting Staff, Regional Medical Center, Memphis Veterans Affairs Medical Center, St Jude Children's Research Hospital

R Christopher Walton, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Healthcare Executives, American Uveitis Society, Association for Research in Vision and Ophthalmology, and Retina Society

Disclosure: Nothing to disclose.

References
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The patient's rash is a major diagnostic sign of Rocky Mountain spotted fever (RMSF). Image courtesy of Bal AK, Kairys SW. Kawasaki disease following Rocky Mountain spotted fever: a case report. Journal of Medical Case Reports 2009, 3:7320. Available at http://www.jmedicalcasereports.com/content/3/1/7320. Accessed July 25, 2013.
The patient's rash is a major diagnostic sign of Rocky Mountain spotted fever (RMSF). Image courtesy of the Centers for Disease Control and Prevention (CDC).
In the United States, the American dog tick (Dermacentor variabilis) is the most commonly identified source of transmission. This tick is actually found mainly east of the Rocky Mountains (distribution is shown). The Rocky Mountain wood tick (Dermacentor andersoni), found predominantly in the mountain states, can transmit RMSF and tularemia to humans. The brown dog tick (Rhipicephalus sanguineus) has recently been identified as a source of RMSF in the southwestern U.S. and along the U.S.-Mexico border, but it is found throughout the country and the world. Image courtesy of the Centers for Disease Control and Prevention (CDC).
 
 
 
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