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 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.