Immune-sensitization to Mycobacterium tuberculosis Among Young Children With and Without Tuberculosis

Identification of young children with Mycobacterium tuberculosis ( Mtb )-infection is critical to curb Tuberculosis (TB)-related pediatric morbidity and mortality. The optimal test to identify young children with evidence of Mtb -infection remains controversial.

Using a TB household contact (HHC) study design among 130 Ugandan children less than 5 years with established Mtb -exposure, we compared the usefulness of the tuberculin skin test (TST) and QuantiFERON Gold Plus (QFT-Plus) to identify children with evidence for Mtb -sensitization. We conducted univariate analysis to compare findings between children with and without TB disease, and performed a logistic regression model to estimate the odds of TB. We performed a sensitivity analysis by stratifying results by age (< 2 years vs. 2-5 years). Finally, we compared results of the QFT-Plus TB tube 1 and TB tube 2 to establish concordance.

A 5 mm TST threshold identified the most children with evidence of Mtb -sensitization; this result was most pronounced in children with TB. Moreover, the odds of TB were 2 times higher [aOR: 2.09 (CI: 1.02 - 4.37)] among children with a positive TST. The QFT-Plus' TB tube 1 and TB tube 2 results were highly correlated.

TST identified more TB-exposed young children with evidence of Mtb- immune-sensitization, when compared to QFT-Plus. These findings are highly relevant for children who are TB HHCs in endemic settings, and most at risk for TB following an exposure. We recommend that TST testing continue to be performed to assess for Mtb -sensitization in young children.