Clinically compatible or epidemiologically linked case that is laboratory confirmed:
- Fourfold or greater change in antibody titer to
C. burnetii phase II or phase I antigen in paired serum specimens taken 3-6 weeks apart OR
- Isolation of
C. burnetii from an appropriate clinical specimen OR
- Demonstration of
C. burnetii in a clinical specimen by detection of antigen or nucleic acid.
Clinically compatible or epidemiologically linked case with a single supportive Immunoglobulin G (IgG) or Immunoglobulin M (IgM) titer.
Definition of clinical illness
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.
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.