Acute infection: A febrile illness usually accompanied by rigors, myalgia, malaise, and retrobulbar headache. Severe disease can include acute hepatitis, pneumonia, and meningoencephalitis. Clinical laboratory findings may include elevated liver enzyme levels and abnormal chest film findings. Asymptomatic infections may also occur.
Chronic infection: Potentially fatal endocarditis may evolve months to years after acute infection, particularly in persons with underlying valvular disease. A chronic fatigue-like syndrome has been reported in some Q fever patients.
Laboratory Criteria For Diagnosis
- Fourfold or greater change in antibody titer to Coxiella burnetii phase II or phase I antigen in paired serum specimens ideally taken 3-6 weeks apart, OR
- Isolation of C. burnetii from a clinical specimen by culture, OR
- Demonstration of C. burnetii in a clinical specimen by detection of antigen or nucleic acid.