What is tuberculosis?

Tuberculosis (TB) is a disease caused by infection with bacteria called Mycobacterium tuberculosis. TB usually affects the lungs (respiratory infection), but it can affect other parts ofthe body as well.

When a person who has a respiratory TB infection coughs, sneezes, or spits, droplets containing TB bacteria are released into the air. If another person breathes
in those droplets, he or she becomes exposed to the bacteria. This is how TB bacteria are typically spread from one person to another.

Not everyone who has TB bacteria in their bodies will become sick. Those who do not become sick are said to have latent TB infection. Those who do become sick have an active infection.

• People with latentTB infections usually have strong natural defense (immune) systems that keep the
TB bacteria from multiplying. They do not develop TB symptoms and cannot spread TB to others. It is
possible, however,for a person with a latent infection
to develop an active infection. This happens to about 1 in 10 people who have untreated latent TBinfections.1

• An active TB infection means the TB bacteria
are multiplying. This will cause a person to have symptoms ofTB disease. Active TB is highly contagious (easily spread from one person
to another) .

Certain people are at greater risk of developing an active TB infection when exposed to TB bacteria. These include people who1-3:
• Have recently (within the past 2 years) been infected with TB bacteria.

• Were not correctly treated forTB infection in the past.

• Have medical conditions (such as pregnancy, HIV infection,diabetes,or cancer) or take medications (such as those used to prevent rejection after an organ transplant) that weaken the immune system.

• Live in (or recently relocated from) parts of the world where the rates ofTB infection are high.

• Are in close contact (either at work , school, or home) with 1 or more people who have an active TB infection.

• Smoke.

• Abuse alcohol or drugs.


Symptoms of an active TB infection may include1.3:

• A long-lasting cough that may bring up bloody mucus (sputum) .

• Chest pains.

• Unexplained weight loss.

• Loss of appetite.

• Weakness or tiredness (fatigue).

• Fever.

• Night sweats.


Without treatment, an active TB infection may cause serious illness or even death. TB is treated with a combination of antibiotics that must be taken for several months.