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Tuberculosis (TB) is a chronic bacterial infection that is spread through the air; it usually infects the lungs. While most people who are affected with TB do not have symptoms (the latent form of the disease), the active form of the disease is more serious, killing nearly two million people each year. Treatment involves taking several antibiotics for at least six months.

What Is Tuberculosis?

Tuberculosis (TB) is a chronic bacterial infection caused by Mycobacterium tuberculosis. It is spread through the air and usually infects the lungs, although other organs and parts of the body can be involved as well. Most people who are infected harbor the tuberculosis bacterium without symptoms. This is known as latent tuberculosis.
If the body's resistance is low because of aging, malnutrition, infections such as HIV, or other reasons, the bacteria may break out of hiding and cause active tuberculosis.
According to World Health Organization (WHO) estimates, each year, eight million people worldwide develop active tuberculosis and nearly two million die. One in 10 people who are infected with tuberculosis may develop active TB at some time in their lives. The risk of developing the active disease is greatest in the first year after infection, but active disease often does not occur until many years later.

Cause of Tuberculosis

The cause of the disease is a bacterium called Mycobacterium tuberculosis. This bacterium usually attacks the lungs. However, TB bacteria can also attack any part of the body such as the kidneys, spine, and brain. If not treated properly, TB can be fatal.


Tuberculosis is spread through the air from one person to another. The bacteria are put into the air when a person with active TB of the lungs or throat coughs or sneezes. People nearby may breathe in these bacteria and become infected.
People cannot get infected with TB through handshakes, sitting on toilet seats, or sharing dishes and utensils with someone who has TB.
Written by/reviewed by:
Last reviewed by: Arthur Schoenstadt, MD
Last updated/reviewed:
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