The Mantoux test involves injecting a small amount of purified protein derivative (PPD) intradermally into the forearm.

After 48–72 hours, the injection site is examined for induration (raised, hardened area).

Clinical uses include:

Screening for latent tuberculosis infection (LTBI).

Supporting diagnosis of active tuberculosis when combined with other tests (chest X-ray, sputum culture).

Identifying individuals at risk (healthcare workers, immunocompromised patients, close contacts of TB cases).

The test does not distinguish between latent and active TB, nor between TB infection and prior BCG vaccination.

Analyte: Immune response to Mycobacterium tuberculosis antigens (PPD).

Result Interpretation (Induration size):

≥ 5 mm: Positive in high-risk groups (HIV, immunosuppressed, recent TB contacts).

≥ 10 mm: Positive in moderate-risk groups (healthcare workers, recent immigrants, certain medical conditions).

≥ 15 mm: Positive in low-risk individuals.

Clinical Use:

Detects prior exposure to TB bacteria.

Helps guide preventive therapy in latent TB cases.

Supports TB control programs and epidemiological studies.