- Positive tuberculosis (PPD) TB skin test along with a clinical history and chest X-ray indicative of active tuberculosis. (Individuals who have a positive PPD test and have a negative chest X-ray, are not symptomatic for tuberculosis, and do not require anti-tuberculosis therapy will be eligible to participate. Participants will be asked if they ever tested positive for tuberculosis. If so, they will not be given a PPD and a chest X-ray and clinical history will be used for evaluation purposes).