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TST interpretation in high-burden settings — DTM&H MCQ

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ModerateEpidemiologyTST interpretation in high-burden settingsDTM&H

A tuberculin skin test survey in a rural community in sub-Saharan Africa shows 75% positivity in adults. The most appropriate interpretation in this high-burden setting is:

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Correct answer: C — The high rate is explained by a combination of BCG vaccination and latent TB infection

In high-burden settings, high TST positivity reflects both BCG vaccination (given at birth in most sub-Saharan African countries) and high rates of latent TB infection. TST cannot distinguish between BCG response and latent infection. This limits its utility for LTBI diagnosis in these populations. IGRA is more specific but expensive and logistically challenging. Not all TST-positive individuals have active TB.

Reference: WHO TB Screening Guidelines; Manson's Tropical Diseases