How does the TB test work?

How do you know if the skin test is positive or negative?

<>If after 3 days the area is red, raised, or bumpy, the test is positive. If not, negative.

i dont really know.... you can ask a doctor

the tb skin test is performed like this

a small amount (less than 1%) of the non-active disease is injected into your arm with a very tiny needle within the skin tissue (not inside your vein) to form a small bubble that eventually shrinks down as the skin absorbs the liquid.

within 48-72 hours-the test will reveal either positive or negative signs. negative is usually a slight red mark that is NOT raised or puffy or no mark left at all. positive is a large,swelled red bump on the arm.

if you have a positive skin test-it does necessarily mean that you have active TB. it means that you have been exposed to it. a chest xray will then be taken that will determine whether or not you have active TB. if active-you are admitted to the hospital for treatment. if non-active, then you are put on medications to help prevent the disease from becoming active in your body and you are monitored closely by your dr

this test is nothing to sweat-i get one every 6 months due to working in a hospital.

The tuberculosis skin test (also known as the tuberculin or PPD test) is a test used to determine if someone has developed an immune response to the bacterium that causes tuberculosis (TB). This response can occur if someone currently has TB or if they were exposed to it in the past. The tuberculin skin test is based on the fact that infection with M. tuberculosis produces a delayed-type hypersensitivity skin reaction to certain components of the bacterium. The components of the organism are contained in extracts of culture filtrates and are the core elements of the classic tuberculin PPD (also known as purified protein derivative). Reaction in the skin to tuberculin PPD begins when specialized immune cells, called T cells, which have been sensitized by prior infection, are recruited by the immune system to the skin site where they release chemical messengers called lymphokines. These lymphokines induce induration (a hard, raised area with clearly defined margins at and around the injection site) through local vasodilation edema, fibrin deposition, and recruitment of other inflammatory cells to the area.