APPLICATION OF THE T-SPOT.TB ASSAY TO IDENTIFY TUBERCULOSIS INFECTION IN CHILDREN

Objective: To explore the value of enzyme-linked immunospot assay for interferon-gamma (T-SPOT.TB) to identify latent tuberculosis infection (LTBI) in children so as to provide the basis for early treatment and management of LTBI in children. Methods: By T-SPOT.TB assay and tuberculin skin test (TST), 47 children who had close contact with active TB cases were monitored for 2 years. Results: 26147 (553%) children were positive by TST. 6147 (12.7%) were positive by the T-SPOT.TB assay. TST results were grouped according to size of indurations. The positive rate of T-SPOT.TB varied between the four groups, (P=0.002) indicating that subjects with a larger TST result were more likely to have LTBI; Following 6 months anti-tuberculosis treatment, T-SPOT.TB results became negative in 4 cases while the number of spots was significantly reduce in a further 2 cases, After 12 months all were negative. 20 children were positive by TST but negative by the T-SPOT.TB assay. After 2 years of follow-up no signs of conversion to active TB were identified in these children; Conclusion: Among children with a high risk of LTBI, the T-SPOT.TB assay appears to be more specific for the diagnosis and identification of LTBI than the TST.