Tuberculosis in Internationally Displaced Children Resettling in Harris County, Texas, USA, 2010-2015¹

Area of Science:

• Public Health
• Infectious Disease Epidemiology
• Clinical Diagnostics

Background:

• US guidelines recommend tuberculosis (TB) screening for children emigrating from high-incidence countries using interferon-gamma release assays (IGRAs) or tuberculin skin tests (TSTs).
• Evaluating the comparative effectiveness and concordance of these tests in a real-world screening setting is crucial for refining public health strategies.

Purpose of the Study:

• To analyze the results of TB screening tests (IGRAs and TSTs) in a cohort of children (<18 years) undergoing health screening in Harris County, Texas.
• To compare the positivity rates and concordance between IGRA and TST in this pediatric immigrant population.
• To assess the impact of factors like region of origin and age on test results and to inform current TB screening guidelines for immigrants.

Main Methods:

• Retrospective analysis of TB screening data from the Harris County Public Health Refugee Health Screening Program (2010-2015).
• Inclusion of children (<18 years) tested with TST, IGRA, or both.
• Statistical analysis to compare test positivity, identify associated factors (region, age), and evaluate test concordance.

Main Results:

• Out of 5,870 children tested, 6.2% had at least one positive TB test.
• Positive test rates varied: TST alone (7.8%), IGRA alone (3.5%), and both TST and IGRA (30.9%).
• TST showed significantly higher positivity than IGRA (OR 2.92). Discordant results (20%) were common, predominantly TST+/IGRA-, likely due to BCG vaccination.

Conclusions:

• Interferon-gamma release assays (IGRAs) demonstrate a lower false-positive rate compared to tuberculin skin tests (TSTs) in pediatric immigrant populations, potentially due to fewer false positives from Bacillus Calmette-Guérin vaccination.
• The high rate of TST+/IGRA- discordant results supports the preference for IGRAs in screening recently immigrated children.
• Findings support the 2018 US immigration guideline change recommending IGRAs for TB screening in this population.