Q fever as a cause of fever of unknown origin and thrombocytosis: first molecular evidence of Coxiella burnetii in Brazil.

We report a case of Q fever in a man who presented with fever of 40 days duration associated with thrombocytosis. Serological and molecular analysis (polymerase chain reaction) confirmed infection with Coxiella burnetii. A field study was conducted by collecting blood samples from the patient's family and from the animals in the patient's house. The patient's wife and 2 of 13 dogs showed seroreactivity. Our data indicate that C. burnetii may be an underrecognized cause of fever in Brazil and emphasize the need for clinicians to consider Q fever in patients with a febrile illness, particularly those with a history of animal contact.