Tuberculosis (TB) is a contagious bacterial infection that usually affects the lungs. In rare cases, it may spread to other body tissues or organs (extrapulmonary TB).

Symptoms of TB vary and may include fever, extreme fatigue, weight loss, night sweats, and a cough that produces bloody sputum. A cough that slowly gets worse over weeks to months may be the only sign of TB.

Tuberculosis is spread when an infected person coughs or sneezes the bacteria into the air and others breathe it in. A person cannot catch the disease by handling things an infected person has touched.

A person who becomes infected with the tuberculosis bacteria may not have any symptoms. This is called inactive (latent) infection and cannot be spread to others. But the infection can become an active disease (active TB) years after the initial infection. This can occur especially if the immune system of the infected person is weakened. Active TB can be spread to others.

A TB skin test (also called a tuberculin skin test, PPD test, or Mantoux test) or a TB blood test (called an interferon-gamma release assay or IGRA) can help identify people who have ever had a TB infection. Tuberculosis often can be successfully treated with specific antibiotics taken for at least 6 months. A person who does not have symptoms but has a TB test that shows an infection may need antibiotics to prevent active disease. If TB is not treated, it can be fatal.