In Tuscany, Tuberculosis incidence is more than triplicate from 1982 to the beginning of the third millennium. The impact of this trend on open population is not known, as updated studies on Tuberculosis prevalence are not available. Tuberculin skin test provides the currently most widely used tool for assessing Tuberculosis transmission in a community and the prevalence of infection as well. The objective of this investigation was the evaluation of tuberculin index by means of the Mantoux test

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... in adolescents eighteen-years old. The study was carried out in 21 secondary schools of Siena and its Province; 1,138 students participated to this survey. The overall prevalence of subjects with a skin reaction size > 5 mm was 1.6%; if the standard cut-off of 10 mm was used, the overall prevalence of a positive skin reaction was 0.4%. Risk factors for a doubtful or positive reaction were previous immunization with BCG and migration from high-endemicity countries. In Italy, studies on tuberculin index in young adults are scanty and controversial: our results show a very low Tuberculosis prevalence and an epidemiological pattern typical of countries with low Tuberculosis endemicity. The slightly increase in Tuberculosis incidence has no impact on the prevalence of latent Tuberculosis infection on our geographical area. We conclude that skin-test screening for Tuberculosis should be addressed to high risk population as migrants from Countries reporting high transmission rate, those recently exposed to an infectious case and health-workers.