eMedicine Specialties > Emergency Medicine > Infectious Diseases

Tick-Borne Diseases, Q Fever: Differential Diagnoses & Workup

Author: Jonathan A Edlow, MD, Associate Professor of Medicine, Department of Emergency Medicine, Harvard Medical School; Associate Chief, Department of Emergency Medicine, Beth Israel Deaconess Medical Center
Contributor Information and Disclosures

Updated: Dec 9, 2008

Differential Diagnoses

Hepatitis
Tick-Borne Diseases, Introduction
Legionnaires Disease
Tick-Borne Diseases, Relapsing Fever
Myocarditis
Tick-Borne Diseases, Rocky Mountain Spotted Fever
Pericarditis and Cardiac Tamponade
Tick-Borne Diseases, Tularemia
Pneumonia, Bacterial
Pneumonia, Viral
Tick-Borne Diseases, Ehrlichiosis

Other Problems to Be Considered

Atypical pneumonia caused by viruses, Chlamydia species, or Mycoplasma should be considered in the differential diagnosis.

Workup

Laboratory Studies

  • Findings of standard laboratory tests are not diagnostic.
  • The WBC count usually is normal.
  • The platelet count can be low initially, with a reactive thrombocytosis reported during convalescence.
  • An elevated hepatic transaminase level is a common finding and is present in nearly 70% patients who require hospitalization.
  • The organism is very infectious, and isolation ought to be done in Biosafety Level 3 laboratories.1 If a clinician thinks Q fever is a likely diagnosis, the laboratory should be notified so that they can take appropriate precautions.
  • Patients with Q fever endocarditis are blood culture negative.

Imaging Studies

  • A chest radiograph is the only imaging study that is likely to be useful. An atypical pneumonia pattern may be observed, similar to the pattern seen with pneumonia caused by viruses and Mycoplasma, Chlamydia, and Legionella species.
  • In the rare patient with prominent neurologic symptoms, CT scanning of the brain may be indicated.
  • In cases of Q fever endocarditis, the cardiac echocardiogram demonstrates vegetations in only 12% of cases.
  • Pericardial effusion may also be seen in Q fever.

Other Tests

  • The diagnosis is based on a high index of suspicion suggested by the epidemiologic features and is proven by serologic testing.
    • Determination of antibodies to C burnetii can be achieved by means of complement fixation, indirect immunofluorescent antibody testing, and enzyme-linked immunosorbent assay. These tests are performed in reference laboratories, and indirect immunofluorescent antibody testing is the reference method of choice. Seroconversion generally occurs between days 7 and 15 and is almost always present by 21 days.
    • In chronic disease, a single elevated level is often diagnostic.
    • Culturing this organism can be accomplished, but this is dangerous because laboratory-transmitted cases are reported.
    • Polymerase chain reaction (PCR) can be used with tissue specimens, but these are not generally available commercially.

Procedures

Although it does not need to occur in the ED, echocardiographic screening of patients with Q fever should be considered.

More on Tick-Borne Diseases, Q Fever

Overview: Tick-Borne Diseases, Q Fever
Differential Diagnoses & Workup: Tick-Borne Diseases, Q Fever
Treatment & Medication: Tick-Borne Diseases, Q Fever
Follow-up: Tick-Borne Diseases, Q Fever
References
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References

  1. Scola BL. Current laboratory diagnosis of Q fever. Semin Pediatr Infect Dis. Oct 2002;13(4):257-62. [Medline].

  2. Raoult D, Fenollar F, Stein A. Q fever during pregnancy: diagnosis, treatment, and follow-up. Arch Intern Med. Mar 25 2002;162(6):701-4. [Medline].

  3. Bernit E, Pouget J, Janbon F, et al. Neurological involvement in acute Q fever: a report of 29 cases and review of the literature. Arch Intern Med. Mar 25 2002;162(6):693-700. [Medline].

  4. Brouqui P, Dupont HT, Drancourt M, et al. Chronic Q fever. Ninety-two cases from France, including 27 cases without endocarditis. Arch Intern Med. Mar 8 1993;153(5):642-8. [Medline].

  5. CDC. Q fever--California, Georgia, Pennsylvania, and Tennessee, 2000-2001. MMWR Morb Mortal Wkly Rep. Oct 18 2002;51(41):924-7. [Medline].

  6. Domingo P, Munoz C, Franquet T, et al. Acute Q fever in adult patients: report on 63 sporadic cases in an urban area. Clin Infect Dis. Oct 1999;29(4):874-9. [Medline].

  7. Harris RJ, Storm PA, Lloyd A, et al. Long-term persistence of Coxiella burnetii in the host after primary Q fever. Epidemiol Infect. Jun 2000;124(3):543-9. [Medline].

  8. Madariaga MG, Rezai K, Trenholme GM, Weinstein RA. Q fever: a biological weapon in your backyard. Lancet Infect Dis. Nov 2003;3(11):709-21. [Medline].

  9. Maltezou HC, Raoult D. Q fever in children. Lancet Infect Dis. Nov 2002;2(11):686-91. [Medline].

  10. McQuiston JH, Holman RC, McCall CL, et al. National surveillance and the epidemiology of human Q fever in the United States, 1978-2004. Am J Trop Med Hyg. Jul 2006;75(1):36-40. [Medline].

  11. Parker NR, Barralet JH, Bell AM. Q fever. Lancet. Feb 25 2006;367(9511):679-88.

  12. Raoult D, Marrie T. Q fever. Clin Infect Dis. Mar 1995;20(3):489-95. [Medline].

  13. Raoult D, Marrie T, Mege J. Natural history and pathophysiology of Q fever. Lancet Infect Dis. Apr 2005;5(4):219-26. [Medline].

  14. Tissot Dupont H, Raoult D, Brouqui P, et al. Epidemiologic features and clinical presentation of acute Q fever in hospitalized patients: 323 French cases. Am J Med. Oct 1992;93(4):427-34. [Medline].

  15. Tissot-Dupont H, Raoult D. Q fever. Infect Dis Clin North Am. Sep 2008;22(3):505-14, ix. [Medline].

  16. Tissot-Dupont H, Vaillant V, Rey S, Raoult D. Role of sex, age, previous valve lesion, and pregnancy in the clinical expression and outcome of Q fever after a large outbreak. Clin Infect Dis. Jan 15 2007;44(2):232-7. [Medline].

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Further Reading

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Keywords

Q fever, tick-borne disease, Coxiella burnetii, C burnetii, fever, vector-borne disease, tick bite, acute Q fever, chronic Q fever, febrile illness

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Contributor Information and Disclosures

Author

Jonathan A Edlow, MD, Associate Professor of Medicine, Department of Emergency Medicine, Harvard Medical School; Associate Chief, Department of Emergency Medicine, Beth Israel Deaconess Medical Center
Jonathan A Edlow, MD is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

Dan Danzl, MD, Chair, Department of Emergency Medicine, Professor, University of Louisville Hospital
Dan Danzl, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, Kentucky Medical Association, Society for Academic Emergency Medicine, and Wilderness Medical Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

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.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Charles V Pollack, Jr, MD, MA, FACEP, Professor, Department of Emergency Medicine, University of Pennsylvania College of Medicine; Chairman, Department of Emergency Medicine, Pennsylvania Hospital
Charles V Pollack, Jr, MD, MA, FACEP is a member of the following medical societies: American Academy of Emergency Medicine and American College of Emergency Physicians
Disclosure: sanofi-aventis Honoraria Consulting; sanofi-aventis Honoraria Speaking and teaching; Schering-Polugh Honoraria Consulting; Schering-Plough Honoraria Speaking and teaching; The Medicines Company Honoraria Consulting; GlaxoSmithKline Grant/research funds Other

 
 
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