Objective: To examine the specificity of QuantiFERON®TB-2G (QFT) in tuberculosis contact investigations of children.
Methods: A schoolgirl was diagnosed with smear-positive pulmonary tuberculosis. To determine the extent of tuberculosis infection among contact schoolchildren, tuberculin skin tests were performed on 75 children enrolled in the school. All the children had been vaccinated with BCG at least once. The QFT test was then given to the 68 children who had tuberculin reactions including erythema larger than 10㎜ in diameter. Written informed consent was obtained from a parent of each child.
Results: The number of infected subjects was 22 based on tuberculin skin test results. Of the 68 contacts, 1 was positive for QFT, 2 were doubtful positive, and the remaining 65 were negative. During the 2-year follow-up, none of the children developed tuberculosis. Specificity was 95.6%.
Conclusions: It was confirmed that the additional use of QFT would reduce the number of indications for chemoprophylaxis cases. The current criteria for the indication of chemoprophylaxis based on a strong tuberculin reaction are considered unreliable, causing many subjects with strong reactions to be given unnecessary preventive medications.
小児肺結核 (childhood tuberculosis)
接触者健診 (contact investigation)