The aim of study is to evaluate the prevalence of latent TB in second generation immigrants from countries with high incidence of tuberculosis (above 20 of 100,000) compare to the control native Israelis without a family member who was born in a country with high incidence of tuberculosis. Using study questionnaire IGRA and tuberculin skin test the investigators expect that the second generation immigrants group will have more positive IGRA test than the control native group.

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