Clinical and laboratory procedures
Demographics, history and clinical findings were recorded systematically using a case report form. All participants underwent peripheral blood testing including QFT. Children suspected of ATB and contact tracing referrals underwent standard diagnostic procedures encompassing TST, QFT, chest X-ray, and, if required, histological and bacteriological evaluation (microscopy, PCR, and culture). Not all participants received TST due to recurrent shortages of Purified Protein Derivative (PPD). For ethical reasons, we did not perform TST, chest X-ray and microbiological studies in the control group. All children with ATB received standard combined antituberculous treatment, children with LTBI and TB contacts aged < 5 years were offered preventive chemotherapy. A subgroup of patients underwent follow-up examination two months after treatment onset.