What is the expected duration for symptoms to develop after TB exposure?

• A. 1 to 2 days
• B. 2 to 3 weeks
• C. 2 to 3 months
• D. 6 months

Answer: (B)

TB symptoms don’t appear immediately after exposure because it takes time for the bacteria to establish infection and for the immune system to respond. The body’s delayed-type hypersensitivity reaction to TB antigens develops over a few weeks, so symptoms such as a persistent cough, fever, night sweats, or weight loss typically begin around two to three weeks after exposure. Shorter times (like 1–2 days) are not enough for infection to take hold and symptoms to develop, while much longer intervals (months) are more characteristic of reactivation or much later onset rather than initial symptomatic disease after a single exposure. This 2–3 week window also aligns with the period in which TB testing (like a skin test) often becomes positive after exposure.