Prevalence of Latent Tuberculosis Infection in Health-care Workers and Students

The prevalence of Latent Tuberculosis Infection \[LTBI\] is defined as 1) tuberculin conversion after a documented negative-baseline tuberculin skin test (TST), 2) positive result of the QuantiFERON-TB Gold (QFT) test performed \[higher response than the cut-off value of 0.35 IU / ml of INF-γ was detected in at least one test tube (TB1 or TB2)\], 3) chest imaging excluding pleural and/or pulmonary lesions suggestive of active tuberculosis and 4) final medical evaluation done by a Specialist in Infectious Diseases which excluded active disease. All four criteria must be met.