Explore the recorded discovery and history of Mycobacterium tuberculosis, with source links and stated limits.
M. tuberculosis is a slow-growing bacterium that causes tuberculosis (TB). Disease usually affects the lungs, but can involve other organs. TB in the lungs can spread through the air. Infection and disease are different: inactive infection causes no TB symptoms and is not contagious. Active disease may cause illness, although symptoms can be mild or absent. Symptoms alone cannot establish a diagnosis; testing and clinical assessment are needed.
Koch announces the discovery of the bacterium that causes tuberculosis at the Berlin Physiological Society. TB disease was known before the organism was identified.
Koch receives the Nobel Prize in Physiology or Medicine for his tuberculosis discovery.
Albert Calmette and Camille Guérin develop BCG, a milestone in preventing severe childhood TB. This dates vaccine development, not the bacterium’s origin.
CDC publishes its first nationwide report on TB disease cases. A surveillance report is not a record of the first person ever infected.
These references do not establish the first human infected with TB. Koch’s 1882 discovery is not a patient-zero event. Index cases can be identified within specific investigations, without dating the first-ever infection.
Source check: 2026-09-16. Educational content; independent scientific review remains pending.