An unusual case of brucellosis in Japan: difficulties in the differential diagnosis from pulmonary tuberculosis.

Human brucellosis is an imported zoonosis extremely uncommon in Japan. Brucellosis was found in a 38-year-old surgeon who had never been abroad; he developed intrapulmonary infiltrates and pleural thickening indistinguishable from pulmonary tuberculosis. Despite extensive antibiotic therapy for tuberculosis he developed systemic serositis. A culture of resected lung tissues grew CO2-required coccobacilli. Polymerase chain reaction test using a specific primer pair for Brucella abortus revealed that the isolated pathogen is highly homologous to B. abortus. We emphasize that undetermined cases of human brucellosis may be present in Japan.