What is tuberculosis?
Tuberculosis (TB) is a bacterial infection that usually affects the lungs (pulmonary TB), but can affect other parts of the body (extrapulmonary TB).

Tuberculosis is classified as latent or active.
In latent TB, the body's immune system has walled off (encapsulated) the bacteria into tiny capsules called tubercles. Although the TB-causing bacteria are in your body, you cannot spread the infection to others. However, you are at risk for developing active TB if your immune system becomes weakened.

In active TB, the infection is spreading in your body and, if your lungs are infected, you can spread the disease to others.

What causes tuberculosis?
Tuberculosis is caused by Mycobacterium tuberculosis, slow-growing bacteria that thrive in areas of the body rich in blood and oxygen, such as the lungs.

What are the symptoms of tuberculosis?
If you have latent TB, you will not have symptoms unless the disease becomes active. Symptoms of active TB may include:

A persistent cough that brings up thick, cloudy, and sometimes bloody mucus (sputum) from the lungs.
Fatigue and weight loss.
Night sweats and fever.
Rapid heartbeat.
Swelling in the neck (because lymph nodes in the neck become infected).
In rare cases, shortness of breath and chest pain.

Initial (primary) TB infection or latent TB can be so mild that you don't even know you have an infection.

How is TB spread to others?
People who have a latent TB infection cannot spread the disease.

Pulmonary TB is contagious. It spreads when a person who has active disease exhales air containing TB-causing bacteria and another person inhales the bacteria from the air.

Extrapulmonary TB cannot spread easily to others.

How is TB diagnosed?
Latent TB is detected with a positive reaction to a tuberculin skin test. Active TB is diagnosed by finding the TB-causing bacteria in a sputum sample (sputum culture) or in samples from other parts of the body. A chest X-ray may also be used to help diagnose active TB.

Extrapulmonary TB is diagnosed by a biopsy and culture, CT scan, or magnetic resonance imaging (MRI).

How is TB treated?
Doctors generally use a combination of four antibiotics to treat active TB, whether it occurs in the lungs or elsewhere. Medications for active TB must be taken for a minimum of 6 months. Almost all people who take their medications as prescribed are cured.

Latent TB usually is treated with one antibiotic for 9 months. This prevents the infection from developing into active disease and reduces the risk of complications.

If doses of the medications are missed or the treatment is not completed, treatment will be extended or must be started again. You may be required to take your medications under the direct observation of a health professional. Direct observation treatment (DOT) has been shown to increase a person's compliance with the lengthy treatment for TB, which in turn increasescure rates. Not completing the treatment can cause the infection to worsen or may lead to the development of an antibiotic-resistant infection that is much harder to treat. If left untreated, active TB can damage the lungs or other organs and can possibly cause death.