 The aim of this project is to analyze the potential contribution of IGRA test QuantiFERON-TB Gold In Tube test QTF-GIT, Cellestis Limited, Carnegie, Victoria, Australia in the diagnosis of tuberculosis TB - active or latent in pediatric subjects 0 and 17 years recently exposed to infection indicated as contacts or with clinical suspicion of active TB, and to compare the results obtained with those of the TuberculinSkin Test TST; gold standard. The project is expected to enroll up to 50 pediatric patients over a 4-year study. Children with access to Ambulatory structures or hospitalized at University Infectious Diseases Clinic or Pediatric Clinic, University Hospital of Siena, or with access to Ambulatory or hospitalized at Pediatric Clinic USL 9 Grosseto will be enrolled. Once obtained the informed consent of patients parents or legal guardians, patients will be enrolled. The doctor will administer a clinical-anamnestic questionnaire, relative to the country of birth and residence, date of arrival in Italy and any stays in the country of origin in case of foreign patient, travels abroad, risk factors for infectious diseases, type of contact with any index case, previous vaccination with BCG, date and outcome of the TST, clinical symptoms and signs suggestive of active TB, report of any instrumental investigation. Together with the collection of blood samples for routine purposes, an additional blood sample will be taken so to run IGRA test. Also patients for whom their medical doctor will independently order to run QTF-GIT test as necessary tool for the clinical diagnosis of TB will be included in the study. 