Prevalence of TB Infection and Risk Factors Associated with LTBI among Household Contacts in Roi Et Province, Thailand [TBN 102]

A study assessed the prevalence of latent tuberculosis infection (LTBI) detected by Interferon-Gamma Release Assay (IGRA) and identified factors associated with LTBI among household contacts of pulmonary tuberculosis patients in Roi Et Province, Thailand. This cross-sectional analytic study was conducted between October 1, 2024, and September 30, 2025. The findings were intended to provide local evidence to support targeted contact investigation, improve LTBI screening strategies, and strengthen community-based tuberculosis prevention and control.

The study included 359 household contacts from 334 index pulmonary tuberculosis patients identified in Roi Et Province. Household contacts served as the unit of analysis, while pulmonary tuberculosis patients were recruited as index cases for contact investigation. LTBI was determined using IGRA. Clinical characteristics of index cases, including GeneXpert results and pulmonary cavitation, as well as household exposure characteristics, were compared between IGRA-positive and IGRA-negative contacts. Multivariable logistic regression was performed to identify factors independently associated with LTBI.

Among the 359 household contacts, 99 (27.6%) had positive IGRA results, indicating LTBI. Most index pulmonary tuberculosis patients were male, approximately half had positive GeneXpert results, and 24.5% had pulmonary cavitation. Household contacts with longer daily exposure to the index patient had a significantly higher prevalence of LTBI (p < 0.001). Pulmonary cavitation in the index patient was also significantly associated with LTBI among household contacts (p < 0.001). After adjustment, household contacts exposed to the index patient for more than 8 hours per day had 2.44 times higher odds of LTBI (adjusted OR 2.44, 95% CI 1.47 to 4.07, p = 0.001). Pulmonary cavitation in the index patient was independently associated with a more than fivefold increase in the odds of LTBI among household contacts (adjusted OR 5.11, 95% CI 2.95 to 8.86, p < 0.001).

The study concluded that more than one-quarter of household contacts of pulmonary tuberculosis patients in Roi Et Province had LTBI, and that prolonged daily exposure and pulmonary cavitation in the index patient were the strongest independent risk factors. As a cross-sectional study, the evidence level is moderate for identifying associations but cannot establish causality. The summary provided does not specify inclusion or exclusion criteria, recruitment procedures beyond contact investigation, funding sources, conflicts of interest, or study limitations. The findings support prioritizing household contacts with prolonged exposure and those exposed to patients with cavitary pulmonary tuberculosis for LTBI screening and tuberculosis prevention programs.

Source: Lawong S. Prevalence of Tuberculosis Infection by Interferon-Gamma Release Assay and Risk Factors Associated with Latent Tuberculosis Infection among Household Contacts of Pulmonary Tuberculosis Patients in Roi Et Province, Thailand. Journal of Health Research. 2026;40(1):285-292.