Tuberculosis among immigrants from developing countries in the province of Milan, 1993-1996

SETTING: The Province of Milan, which has high rates of immigration from developing countries, and the Villa Marelli Institute (VMI), Reference Centre for Tuberculosis Control of Lombardy. OBJECTIVE: To describe epidemiology and clinical patterns of tuberculosis among immigrants from developing countries (IDCs) in the Province from 1993 to 1996. DESIGN: Retrospective analysis of the registries of the Regional Bureau for Public Health and of the VMI concerning immigrant patients with active TB living in the Province. Restriction fragment length polymorphism (RFLP) analysis of the available strains to detect recent transmission among immigrants. RESULTS: IDCs represented 22.8% of all TB cases. The standardised incidence rate was eight times higher in IDCs compared to Italians. Of 596 cases notified in IDCs, 524 (87.9%) had been referred at least once to the VMI. Of these, 77.2% were diagnosed within 5 years of arrival, and 86.6% were brought to medical attention because of symptoms. RFLP fingerprinting demonstrated that the mean period of stay in Italy was significantly higher in clustered than in non clustered patients (61.5 versus 37.3 months). Spread to the native population was episodic. CONCLUSIONS: The incidence of TB is higher among more recent immigrants (i.e., Peruvians). TB cases are largely due to reactivation of infection occurring in the country of origin. Preventive measures for early diagnosis of disease or chemoprophylaxis of dormant infection are not regularly performed, but should be implemented for those immigrants at high risk.