When do you say someone is positive of Mantoux test?

A Mantoux test is done by injecting a very small amount of TB protein ( antigens) under the top layer of skin. The skin test is then read 2 or 3 days later, a positive test, doesn't always mean someone has TB; it just means that you have been exposed to TB at sometime in your life, a follow up XRay or CT scan to reveal if there is an active infection should be done.

A sputum test can also be done to determine if there is active infection.