Material and Method: Descriptive cohort study was carried out in Srinagarind Hospital, Khon Kaen University, North-East Thailand. A smear positive pulmonary tuberculosis mother with productive cough was diagnosed on the fi fth day of admission. The authors urged parents of all exposed neonates to accept isoniazid (INH) prophylaxis for their infants for six months. All neonates underwent chest x ray (AP, lateral view) and tuberculin skin test on the 24 months follow-up.

Results: The 48 neonates were identifi ed as exposed. The age of follow-up ranged from 30 to 32 months. Only three were lost to follow-up. Of the remaining 45 neonates, six refused to take INH prophylaxis. Complete six months of INH prophylaxis were observed in 27 (60%) of 39 contacts. Tuberculin skin tests (TST) were performed in all of 45 contacts. No cases were positive for TST. Abnormal chest radiographies were found in nine of INH group, three patients had hilar lymphadenopathy and six had pneumonia. The repeat chest x ray, two weeks later, was normal in all cases. After 30 to 32 months follow-up, none of the 39 neonates who received INH prophylaxis or the six neonates progressed to have active tuberculosis.

Conclusion: In exposed neonate identifi ed as the high-risk group, appropriate INH prophylaxis, and long-term follow-up, especially in the fi rst-2 years, seemed to be effective in preventing the development of active tuberculosis.

Keywords: Neonatal exposure, Pulmonary tuberculosis, Isoniazid prophylaxis, Outcome