Infectious Diseases >> Tuberculosis

What is it?

Tuberculosis is an infection caused by a bacterium called Mycobacterium tuberculosis. It mostly attacks the lungs (as Pulmonary TB) but can also attacks central nervous system, the lymphatic system, the circulatory system, the genitourinary system, bones joint and even the skin. The infection of TB has two distinct stages. First, bacteria are inhaled into the lungs, where most are destroyed by the immune system. Bacteria that are not destroyed are trapped by the immune system inside hard, walled capsules, known as tubercles, which are composed of a number of different types of cells. Encased bacteria in the tubercles cannot cause damage or symptoms. Many cases diseases never progress beyond this point. Only a small fraction of those infected will develop active disease, the second stage of TB. In this stage the bacteria escape control of the tubercles and infect other sites in the lungs. Bacteria may also invade the bloodstream and the lymphatic system and spread throughout the body.