Polymerase chain reaction (PCR) was applied to confirm the diagnosis of brucellosis and to study its clearance in response to the standard treatment regimen with doxycycline and rifampin at hospitals in Callao and Lima, Peru. The PCR confirmed the diagnosis in 23 (91.7%) patients with brucellosis including 12 culture-confirmed cases. For patients treated at the hospital in Callao, PCR was positive for all samples collected during and at the conclusion of treatment and for 76.9% of follow-up samples collected on average 15.9 weeks after completion of treatment. For patients treated at the hospital in Lima, PCR tests were positive for 81.8% of samples collected during treatment, for 33.3% of samples collected at the conclusion of treatment, and for > or = 50% of samples collected at first, second, and third post-treatment follow-up. Thus, Brucella DNA may persist in the serum weeks to months after completion of the standard treatment regimen.

During home visits and using a point-of-care test for brucellosis, we screened the household members of adult patients found to have brucellosis by investigation at the Hospital Nacional Daniel Alcides Carrión in Callao, Peru. A total of 206 household members of 43 patients were screened, and 15 (7.3%) household members in 10 (23.3%) households tested seropositive. Brucellosis was diagnosed in 14 of them, all but 4 presenting with acute or subacute uncomplicated disease. Regardless of attempts to control brucellosis in Peru, the disease continues to be reasonably common among household members of brucellosis patients. Household members presumably remain the single most important identifiable risk group in an urban setting, and screening them provides an effective means for their early diagnosis. Although contact with livestock was rare, the consumption of unpasteurized dairy products was reported by almost all patients with brucellosis, their household members, and hospitalized non-brucellosis patients.