Disease of the lungs caused by Mycobacterium tuberculosis, a bacterium first described by Robert Koch. Since 1990, a resurgence of the epidemic has been observed. Antibiotic-resistant strains are especially problematic. Around 1.4 million people are dying each year from “consumption.” Not everyone infected with the bacterium contracts tuberculosis. The risk is especially high in people with a weakened immune system. As such, tuberculosis is the chief cause of death in people with AIDS.