Many people mistakenly believe that Tuberculosis infections are a thing of the past, but the truth is that there are thousands of new cases each year in the United States. The infection is caused by a bacterium called Mycobacterium tuberculosis, and mainly affects the lungs and respiratory system. If undetected and untreated, TB can also spread to other parts of the body including the digestive system, and even the central nervous system. Contrary to popular belief, not everyone infected actually becomes sick. But persons with a latent TB infection (LTBI) can easily spread the infection to others, particularly if they are in a high risk population.