Latent Tuberculosis in Second Generation Immigrants From High Risk Countries Compare to Low-risk Young Israeli Adults

Inclusion Criteria: * Age 18-25 * Men and women * Second generation immigrants from countries with high incidence of tuberculosis (above 20 of 100,000). * Native Israelis without a family member who was born in a country with high incidence of tuberculosis. Exclusion Criteria: * Prior contact with a tuberculosis patient * Working (more than a month) in high risk setting such as health care workers, working with immigrants from countries with high incidence of tuberculosis. * HIV infection and any immunodeficiency condition. * Recent live-virus vaccination * Acute infectious disease * Prior serious reaction to tuberculin skin test * Pregnancy