A positive Mantoux test indicates what?

A positive Mantoux test indicates what?

• A. Immunity from vaccination
• B. No exposure
• C. Development of antibodies following exposure to TB
• D. Active TB infection

Answer: (C)

A positive Mantoux test shows that the body has been sensitized to TB antigens after exposure. The test is a delayed-type hypersensitivity reaction driven by memory T cells: tuberculin is injected intradermally, and if you’ve been exposed to TB (or vaccinated with BCG), your T cells recognize the antigens and release substances that cause induration within 48–72 hours. This indicates an immune response to TB antigens, which can reflect latent infection or prior vaccination, but by itself does not prove active disease.

A positive Mantoux test shows that the body has been sensitized to TB antigens after exposure. The test is a delayed-type hypersensitivity reaction driven by memory T cells: tuberculin is injected intradermally, and if you’ve been exposed to TB (or vaccinated with BCG), your T cells recognize the antigens and release substances that cause induration within 48–72 hours. This indicates an immune response to TB antigens, which can reflect latent infection or prior vaccination, but by itself does not prove active disease.