Medical Content Created by the Faculty of the
Harvard Medical School
Tuberculosis is a bacterial infection that most often involves the lungs, but can involve many other organs. Although antibiotics can treat most cases, TB remains one of the most common causes of death worldwide. The TB skin test, also called the purified protein derivative (PPD) test or Mantoux test, shows if you've ever been infected with the bacteria that cause tuberculosis. Infections with these bacteria can be active or inactive. In active infections, the bacteria are reproducing rapidly, and the person is contagious when he or she coughs. In people with inactive infections, the bacteria are alive deep within the lungs, but "asleep." Because inactive infections can later "wake up" and become active, it is important to recognize and treat both types of TB infections.