16. A positive intradermal skin tuberculin test (purified protein derivative [PPD] 5 tuberculin unit [TU]) of ≥5 mm induration read at 48 to 72 hours or positive QuantiFERON-gold testing. Signs or symptoms suggestive of active TB (e.g. new cough lasting >14 days or a change in chronic cough, persistent fever, unintentional weight loss, night sweats) upon review of medical history and/or physical examination. If the patient is thought to have a false-positive PPD because of prior BCG vaccination and it is known that the patient has been negative on testing obtained outside the protocol for M. tuberculosis infection using a cell-based interferon gamma assay the patient is eligible for enrollment.