Background: The Hospital Ferreira Machado, utilized, in part, as a clinical training center for graduate students from the Faculdade de Medicina de Campos, admitted 65 tuberculosis (TB) patients in 2001. Objective: To estimate the prevalence of positive tuberculin skin tests (TST) among medical students during distinct periods of their training and to identify and analyze correlated factors. To compare positivity rates, taking into account the booster effect, and estimate incidence of positive TST by class year. Methods: A cross-sectional study was conducted among 500 students registered in the first semester of 2002. Using a structured and validated questionnaire, data regarding demographics, BCG vaccination and potential exposure to TB patients were obtained. A professional licensed by the Health Department administered the TSTs, and the twostep Mantoux method (PPD Rt23) was used. Results: Of the 500 eligible subjects, 316 (63.2%) were excluded. Analysis showed increasing two-step TST positivity rates corresponding to extent of clinical experience (4%, 6.4% and 13.1%) and a tendency toward correlation with professional level. The highest percentage of positive TSTs was found during the period of clinical training, which corresponded to the time of greatest exposure to patients (1000 hours). Conclusions: a) the TST positivity rate was high (7.9%) among students; b) TST was correlated with in-hospital training stage; c) evaluation of the booster effect lead us to highly recommended boosters in order to reduce the number of false-negative TST results.

Keywords: Tuberculin. Tuberculin test. Tuberculosis. Students/Medical. Cross-sectional studies.