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Q Fever: Clinical Description

Acute Infection

  • Only about one-half of all people infected with C. burnetii show signs of clinical illness.
  • Most acute cases of Q fever begin with sudden onset of one or more of the following:
    • high fevers (up to 104-105°F)
    • severe headache
    • general malaise
    • myalgia
    • chills and/or sweats
    • non-productive cough
    • nausea
    • vomiting
    • diarrhea
    • abdominal pain
    • chest pain
  • Fever usually lasts for 1 to 2 weeks.
  • Weight loss can occur and persist for some time.
  • Thirty to fifty percent of patients with a symptomatic infection will develop pneumonia.
  • A majority of patients have abnormal results on liver function tests and some will develop hepatitis.
  • Other potential complications include miscarriage in pregnant women, myocarditis, encephalitis, osteomyelitis, and granulomatous hepatitis.
  • In general, most patients will recover to good health within several months without any treatment.
  • Only 1%-2% of people with acute Q fever die of the disease.
  • Those who recover fully from infection may possess lifelong immunity against re-infection.

Chronic Infection

  • Chronic Q fever is uncommon (<5% of acutely infected patients will develop chronic infection), but it is much more serious than the acute disease.
  • Chronic Q fever is characterized by infection that persists for more than 6 months.
  • Chronic infection may occur within months or as long as 20 years after the initial acute infection.
  • Chronic Q fever most commonly presents as endocarditis (60-70% of all chronic Q fever cases), generally involving either the aortic or mitral heart valves.
  • Q fever endocarditis is more common in persons who have pre-existing valvular heart disease or have a history of vascular graft.
  • Chronic Q fever may occur more frequently in immunosuppressed persons (such as organ transplant patients, cancer patients, and those with chronic kidney disease) and pregnant women.
  • Chronic infection may have a high fatality rate (up to 37% of chronic Q fever endocarditis cases result in fatalities).
  • Death among Q fever endocarditis case-patients can be reduced to 10% with appropriate antibiotic therapy.