DefinitionPulmonary tuberculosis (TB) is a contagious bacterial infection that mainly involves the lungs, but may spread to other organs.Alternative NamesTB; Tuberculosis - pulmonaryCauses, incidence, and risk factorsPulmonary tuberculosis (TB) is caused by the bacteria Mycobacterium tuberculosis (M. tuberculosis). You can get TB by breathing in air droplets from a cough or sneeze of an infected person. This is called primary TB.In the United States, most people will recover from primary TB infection without further evidence of the disease. The infection may stay asleep or nonactive (dormant) for years. However, in some people it can reactivate.Most people who develop symptoms of a TB infection first became infected in the past. However, in some cases, the disease may become active within