BCG vaccination and household TB exposure in childhood tuberculosis: a community-based case-control study in rural Bangladesh.

Abstract

Background: BCG vaccination and household exposure to tuberculosis (TB) are central to childhood TB control, yet their delivery and effectiveness vary considerably across communities. Evidence from community-based studies in high-transmission, resource-limited settings remains sparse, particularly among marginalised populations such as tea-garden worker communities. This study evaluates their protective effect against childhood TB in rural Bangladesh to address this gap.

Methods: We conducted a community-based case-control study in Moulavibazar District, enrolling children aged 2-14 years from January 8 to April 30, 2023. Cases had newly diagnosed, confirmed TB; controls were community-matched by neighborhood children without respiratory symptoms. We used multivariable logistic regression to calculate adjusted odds ratios (aORs). The Hosmer-Lemeshow goodness-of-fit test was used to assess model calibration. For the Random Forest model, variable importance was assessed using mean decrease in accuracy (MDA) with permutation-based testing.

Results: The dataset comprised 207 cases and 207 controls, with a mean age of 10.09 ± 3.69 years among cases and 9.38 ± 3.37 years among controls. The multivariable analysis identified adolescent age (11-14 years vs. 2-5 years: aOR 2.53, 95% CI = 1.33-4.80), male sex (aOR 1.79, 95% CI = 1.19-2.71), and a family history of TB within the last 6 months (aOR 1.92, 95% CI = 1.22-3.03) as having an association with TB. BCG vaccination demonstrated a significant protective association, reducing the odds of TB by 57% (aOR 0.43, 95% CI = 0.20-0.93). A random forest model confirmed these as the most important predictors, achieving a classification accuracy of 71.6% (AUC = 0.74, sensitivity = 68.5%, specificity = 73.9%).

Conclusion: In rural Bangladesh, childhood TB is associated with adolescent age, male sex, and household exposure. Intensifying universal BCG vaccination and prioritizing household TB exposure assessment, especially for adolescent boys, are critical to reducing the disease burden.

Clinical trial number: Not applicable.