Brucellosis: an unusual cause of a child's fever of unknown origin.

A 3-year-old Wisconsin native with the symptoms of chronic fever, hepatosplenomegaly, and inability to walk, was found to have an elevated anti-Brucella titer. Blood and bone marrow cultures grew Brucella melitensis, biotype 3. This infection was likely acquired during a trip to Mexico several months earlier during which the child had ingested raw milk. The patient's father was also discovered to have brucellosis. Both were successfully treated with antibiotic therapy. Although brucellosis has been almost totally eradicated in the United States, in the appropriate setting it should be considered as a possible cause of fever of unknown origin in a child.