Rocky Mountain Spotted Fever Workup

  • Author: Burke A Cunha, MD; Chief Editor: Michael Stuart Bronze, MD   more...
 
Updated: Sep 14, 2011
 

Approach Considerations

Rocky Mountain spotted fever (RMSF) diagnosis relies on clinical (fever, rash, myalgia) and epidemiologic (tick exposure) criteria. However, a clinical diagnosis of RMSF is difficult to establish, and laboratory findings are nonspecific. Immunologic methods for detection of rickettsiae are unavailable in most clinics. Even so, basic laboratory tests should be obtained, including the following: complete blood count (CBC), electrolytes, renal function tests, liver function tests, and coagulation panel.[15]

After exposure to vector ticks, patients who develop fever, petechial rash, and vomiting require antibiotic therapy. Antibiotic therapy should be initiated before laboratory confirmation is available.

Laboratory findings can include the following:

  • White blood cell (WBC) count - Leukopenia is present initially, then mild leukocytosis; patients usually have a normal WBC count
  • Platelets - Thrombocytopenia (< 150,000 cells/µL) occurs in 32-52% of patients; abnormalities indicative of DIC are present in severely ill patients
  • Hemoglobin and hematocrit - Anemia is present in 5-24% of patients
  • Aminotransferase levels - Mildly elevated in 36-62% of patients
  • Hyponatremia - Present in 19-56% of cases
  • Bilirubin levels – Increased in 8-9% of patients.
  • Mild cerebrospinal fluid pleocytosis with monocyte predominance
  • Azotemia - Develops in 12-14% of cases
  • Prothrombin time and activated partial thromboplastin time - May be elevated

Anemia, an increased blood urea nitrogen (BUN) level, or abnormal liver function test results are found in 30% of patients. Late findings associated with advanced disease include signs of multiorgan failure, such as elevated BUN, creatinine, and creatinine kinase levels.

Serology

Diagnosis is confirmed based on indirect immunofluorescent antibody (IFA) test results, latex agglutination, or enzyme immunoassay. Serology specific for R rickettsii infection develops within 6-8 weeks. Serologic test results are negative prior to convalescence.

Blood culture

Isolation of R rickettsii from the blood is possible, but few laboratories perform this isolation because of biohazard concerns. This is an insensitive test because most Rickettsia is found in the vascular endothelial cells, not in the bloodstream.

Imaging studies

Obtain a chest radiograph in patients who appear significantly ill or have abnormal lung findings on physical examination. Chest radiographs that show an early pulmonary infiltrate should prompt consideration of a different diagnosis.

Computed tomography (CT) scanning or magnetic resonance imaging (MRI) are indicated for altered mental status or neurologic deficits and may reveal infarction, edema, and meningeal enhancement.

Lumbar puncture

Lumbar puncture usually is performed as part of the workup for suspected meningitis. Pleocytosis is found in 34-38% of cases. Usually 10-100 cells/µL with either lymphocytic or polymorphonuclear cell predominance are found. Increased protein is found in 30-35% of cases; the glucose level usually is normal.

Other tests

The Weil-Felix test is used to detect cross-reacting antibodies against Proteus vulgaris antigens OX-2 and OX-19. This test lacks sensitivity and specificity, and better tests are now available. If the Proteus titer is greater than or equal to 1:320 or if a 4-fold or greater rise to either Proteus OX-19 or OX-2 antigens is observed, an RMSF case that is clinically compatible is considered probable.

Electrocardiography may be used to indicate whether myocardial or conduction abnormalities are present.

Next

Skin Biopsy

Direct immunofluorescent microscopy, if available, may be used for rapid histologic diagnosis of Rocky Mountain spotted fever (RMSF). Immunofluorescent or immunoperoxidase staining of R rickettsii in a biopsy skin or organ specimen is sensitive (73%) and specific (100%).[16] However, because direct immunofluorescence has a 30% false-negative rate, patients should be treated even if the test is negative and the suspicion is high.

Antibodies to specific rickettsial antigens are detected by indirect immunofluorescence (most specific), latex agglutination, and enzyme immunoassay. The diagnostic titer is 1:64 for indirect immunofluorescence and latex agglutination.

Amplification of R rickettsii deoxyribonucleic acid (DNA) with polymerase chain reaction (PCR) assay has not been proven to be a sensitive diagnostic method except for later in the disease course, particularly in fatal cases. It has been successful when applied to biopsy skin samples during rickettsioses and also when applied to ticks. According to Walker and Raoult in 2000, the primers used amplify genes of the 17-kD protein citrate synthetase and rickettsial OmpA and allow the identification of any rickettsial organism.

Previous
Proceed to Treatment & Management
 
 
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, and 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, and Pennsylvania Medical Society

Disclosure: Nothing to disclose.

Chief Editor

Michael Stuart Bronze, MD  Professor, Stewart G Wolf Chair in Internal Medicine, Department of Medicine, University of Oklahoma Health Science Center

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

Disclosure: Nothing to disclose.

Additional Contributors

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

  1. Sexton DJ, Corey GR. Rocky Mountain "spotless" and "almost spotless" fever: a wolf in sheep's clothing. Clin Infect Dis. Sep 1992;15(3):439-48. [Medline].

  2. Salgo MP, Telzak EE, Currie B, et al. A focus of Rocky Mountain spotted fever within New York City. N Engl J Med. May 26 1988;318(21):1345-8. [Medline].

  3. Openshaw JJ, Swerdlow DL, Krebs JW, et al. Rocky mountain spotted fever in the United States, 2000-2007: interpreting contemporary increases in incidence. Am J Trop Med Hyg. Jul 2010;83(1):174-82. [Medline]. [Full Text].

  4. Stromdahl EY, Jiang J, Vince M, Richards AL. Infrequency of Rickettsia rickettsii in Dermacentor variabilis removed from humans, with comments on the role of other human-biting ticks associated with spotted fever group Rickettsiae in the United States. Vector Borne Zoonotic Dis. Jul 2011;11(7):969-77. [Medline].

  5. Marshall GS, Stout GG, Jacobs RF, et al. Antibodies reactive to Rickettsia rickettsii among children living in the southeast and south central regions of the United States. Arch Pediatr Adolesc Med. May 2003;157(5):443-8. [Medline].

  6. Zavala-Castro JE, Dzul-Rosado KR, León JJ, Walker DH, Zavala-Velázquez JE. An increase in human cases of spotted fever rickettsiosis in Yucatan, Mexico, involving children. Am J Trop Med Hyg. Dec 2008;79(6):907-10. [Medline].

  7. Demma LJ, Holman RC, Mikosz CA, et al. Rocky mountain spotted fever hospitalizations among American Indians. Am J Trop Med Hyg. Sep 2006;75(3):537-41. [Medline].

  8. Holman RC, McQuiston JH, Haberling DL, Cheek JE. Increasing incidence of Rocky Mountain spotted fever among the American Indian population in the United States. Am J Trop Med Hyg. Apr 2009;80(4):601-5. [Medline].

  9. Kirkland KB, Wilkinson WE, Sexton DJ. Therapeutic delay and mortality in cases of Rocky Mountain spotted fever. Clin Infect Dis. May 1995;20(5):1118-21. [Medline].

  10. Archibald LK, Sexton DJ. Long-term sequelae of Rocky Mountain spotted fever. Clin Infect Dis. May 1995;20(5):1122-5. [Medline].

  11. Chen LF, Sexton DJ. What's new in Rocky Mountain spotted fever?. Infect Dis Clin North Am. Sep 2008;22(3):415-32, vii-viii. [Medline].

  12. Sexton DJ, Gallis HA, McRae JR, Cate TR. Letter: Possible needle-associated Rocky Mountain spotted fever. N Engl J Med. Mar 20 1975;292(12):645. [Medline].

  13. Buckingham SC, Marshall GS, Schutze GE, et al. Clinical and laboratory features, hospital course, and outcome of Rocky Mountain spotted fever in children. J Pediatr. Feb 2007;150(2):180-4, 184.e1. [Medline].

  14. Byrd RP Jr, Vasquez J, Roy TM. Respiratory manifestations of tick-borne diseases in the Southeastern United States. South Med J. Jan 1997;90(1):1-4. [Medline].

  15. Chapman AS, Bakken JS, Folk SM, et al. Diagnosis and management of tickborne rickettsial diseases: Rocky Mountain spotted fever, ehrlichioses, and anaplasmosis--United States: a practical guide for physicians and other health-care and public health professionals. MMWR Recomm Rep. Mar 31 2006;55:1-27. [Medline].

  16. Procop GW, Burchette JL Jr, Howell DN, Sexton DJ. Immunoperoxidase and immunofluorescent staining of Rickettsia rickettsii in skin biopsies. A comparative study. Arch Pathol Lab Med. Aug 1997;121(8):894-9. [Medline].

  17. Markley KC, Levine AB, Chan Y. Rocky Mountain spotted fever in pregnancy. Obstet Gynecol. May 1998;91(5 Pt 2):860. [Medline].

  18. Holman RC, Paddock CD, Curns AT, Krebs JW, McQuiston JH, Childs JE. Analysis of risk factors for fatal Rocky Mountain Spotted Fever: evidence for superiority of tetracyclines for therapy. J Infect Dis. Dec 1 2001;184(11):1437-44. [Medline].

  19. Minniear TD, Buckingham SC. Managing Rocky Mountain spotted fever. Expert Rev Anti Infect Ther. Nov 2009;7(9):1131-7. [Medline].

  20. Lochary ME, Lockhart PB, Williams WT Jr. Doxycycline and staining of permanent teeth. Pediatr Infect Dis J. May 1998;17(5):429-31. [Medline].

 
Previous
Next
 
The palm of a patient with Rocky Mountain spotted fever exhibiting the classic petechial rash associated with the disease. Courtesy of Sadhana Sathe, MD, PhD.
The petechial rash of Rocky Mountain spotted fever affecting the sole and the dorsum of the patient's foot. Courtesy of Sadhana Sathe, MD, PhD.
 
 
 
All material on this website is protected by copyright, Copyright © 1994-2012 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.

DISCLAIMER: The content of this Website is not influenced by sponsors. The site is designed primarily for use by qualified physicians and other medical professionals. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.