Who what is positive ppd

Exposure: It is a sign that you have been exposed to tuberculosis, that you carry the germs for TB in either active or dormant form. Exposure can be recent or very old. People who had vaccination for TB can have a positive PPD in the first few years after receiving the vaccine.

TB infection: A true positive ppd(purified protein derivitive) indicates that the person has been infected with tuberculosis. It does not necessarily mean that person has active tb. Most people after initial infection contain the disease in their tissues by immune mechanisms. 10% will reactivate their disease in their lifetime, 5%risk within 2 years of PPD skin test conversion and 5% risk the rest of life.