Study objectives: To emphasize epidemiologic, clinical, or radiologic characteristics whose detection could lead to an early diagnosis and to enhance therapeutic efficacy.
Patients: Eighty hospitalized patients from 1982 to 1996.
Design: The diagnosis of Q fever infection was serologically confirmed in all the patients (phase II Coxiella burnetii antibody) using the complement fixation test and/or the indirect immunofluorescence antibody test.
Results: Patients from rural and urban areas were noted in the same proportion; however, the usual epidemiologic factors such as contact with cats or farm animals were found in 40% of the patients. Mean age+/-SD was 49+/-20 years, and there was a higher sex ratio of male to female patients (1:3.44). We found a specific seasonal distribution since 80% of the cases occurred between February and May. Delay before referring to hospital was 8.2+/-7.8 days, while 69.3% of the patients received an antibiotic treatment that was mainly penicillin or cephalosporin. The dominant clinical features were dry cough and high fever, as the maximal temperature reached more then 40 degrees C in 58% of the patients. Digestive symptoms were rare. WBC count remained within normal range in 80% of the cases with a low proportion of lymphocytes in half of the patients, and the sedimentation rate was usually elevated (55+/-34 mm). Altered liver function consisted more frequently in an elevated level of alkaline phosphatase (70% of the cases) than transaminases, while hyponatremia was frequently mentioned (28.2% of the patients). We found radiologic evidence of unique lobar or segmental alveolar opacity involving more likely the lower lobes in 55 patients, and multiple or interstitial opacities in the others. Chest radiographs were considered normal in eight patients. The clinical response was favorable in all the patients with a reduction in fever 4.8+/-3.9 days after the start of treatment with the second antibiotic that included mainly erythromycin or quinolones, and chest radiographs returned to normal in 81% of the patients within the first month.