Tuberculosis in Singapore

Yoseph Leonardo Samodra

(Jan 13, 2026)

Advancing Tuberculosis Detection Beyond Symptom- and Single-Test–Based Approaches

• Demonstrated that subclinical pulmonary TB constitutes a substantial proportion of culture-confirmed cases, with many patients lacking cough yet exhibiting radiographic abnormalities and high smear positivity, indicating overlooked transmission potential.
• Provided evidence that symptom-based screening alone is insufficient, particularly in older adults and immunocompromised populations, supporting the need for imaging- and molecular-enhanced screening strategies.
• Quantified limitations of existing diagnostic prediction models (moderate AUCs), highlighting gaps in current case-finding algorithms.
• Showed that CD8⁺ T-cell responses (QFT-Plus TB2–TB1) improve sensitivity for detecting active TB and recent infection, offering incremental diagnostic value beyond standard IGRA positivity.
• Identified biological markers that can help differentiate recent infection and active disease from remote latent TB, informing risk-stratified clinical decision-making.

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Optimizing Contact Investigation, Testing Windows, and Post-Exposure Follow-Up

• Established that over one-quarter of IGRA conversions occur after 10 weeks post-exposure, demonstrating that early repeat testing risks missing clinically relevant TB infection and early disease.
• Provided population-level evidence to support extending repeat QFT testing to ≥10 weeks in national TB contact investigation programs.
• Identified a measurable burden of active TB developing among IGRA-negative contacts, indicating residual risk despite negative screening results.
• Defined high-risk subgroups among IGRA-negative contacts (older age, diabetes, renal failure, smear-positive exposure, household or congregate settings) who warrant enhanced surveillance and prolonged follow-up (up to 24 months).
• Integrated immunological, clinical, and exposure data to inform risk-adapted contact management strategies rather than uniform testing protocols.

See also: Yoseph Samodra

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Informing Population-Level and Preventive TB Control Strategies

• Demonstrated strong dose–response and synergistic effects of multiple unhealthy lifestyle factors (smoking, underweight, inactivity, alcohol use, poor diet) on active TB risk in older adults.
• Showed that individuals with multiple lifestyle risk factors had markedly elevated TB risk (up to ninefold), particularly among those with diabetes, underscoring effect modification.
• Highlighted the importance of multisectoral, lifestyle-based TB prevention strategies alongside biomedical interventions in moderate-incidence settings.
• Provided evidence to support targeted TB preventive treatment (TPT) by combining exposure history, immunological markers, comorbidities, and lifestyle risk profiles.
• Contributed to policy-relevant evidence aligned with long-term TB elimination goals, emphasizing early detection, differentiated follow-up, and upstream risk reduction.

See also: Lin TB Lab

References:

1. Chew, Y.R., Tay, J.Y., Kyaw, W.M., Chia, P.Y. and Ng, D.H.L., 2025. Subclinical disease among people with culture-confirmed pulmonary tuberculosis in Singapore-a retrospective study. International Journal of Infectious Diseases, 153, p.107768.
2. Kyaw, W.M., Tay, J.Y., Lim, L.K.Y. and Ng, D.H.L., 2025. Time interval for QuantiFERON-TB Gold Plus conversion after last exposure with tuberculosis. ERJ Open Research, 11(3).
3. Tavitian-Exley, I., Kyaw, W.M., Kang-Yang, L.L., Foo, K., Boudville, I.C., Cutter, J.L. and Ng, D.H.L., 2024. Risk factors for tuberculosis among close IGRA-negative contacts of persons with infectious tuberculosis in Singapore. International Journal of Infectious Diseases, 147, p.107166.
4. Li, H., Chee, C.B., Geng, T., Pan, A. and Koh, W.P., 2022. Joint associations of multiple lifestyle factors with risk of active tuberculosis in the population: the Singapore Chinese Health Study. Clinical Infectious Diseases, 75(2), pp.213-220.
5. Chee, C.B.E., Kyi-Win, K., Tan, S. and Wang, Y.T., 2025. QuantiFERON-TB Gold Plus CD8+ T cell responses in contacts with tuberculosis disease and recent tuberculosis infection. Microbiology Spectrum, 13(12), pp.e01353-25.

TBN 006