Tuberculosis, consumption, or just TB killed more people than any other disease during the 19th and early-20th centuries, according to the Harvard University Library. It is caused by a bacterium called Mycobacterium tuberculosis which usually attacks the lungs, but can also hit other parts of the body such as the kidney, spine, and brain. oday, TB is rare in wealthier countries, but second only to HIV/AIDS as the greatest killer worldwide.