ABSTRACT

Among tests presently used in clinical medicine, the tuberculin skin test (TST) is one of the few that were introduced into clinical use 100 years ago. Given such a long history of use, it may seem surprising that the interpretation of the TST remains controversial today. However, this reflects the changing epidemiology, clinical features, investigation, and management of tuberculosis (TB). In industrialized countries, new problems have arisen in the interpretation of the TST in certain high-risk populations because of aging, HIV infection, intravenous drug use, and other phenomena that may adversely affect immune responsiveness.