What causes tuberculosis?

The bacteria can enter the lungs when a person breathes in airborne particles released by someone with infectious tuberculosis of the lungs or throat. Close, repeated contact in an enclosed space makes spread more likely. Tuberculosis does not usually spread through sharing food, touching surfaces, or a casual handshake.

After infection, the bacteria may remain inactive, called latent tuberculosis infection, or multiply and cause active disease. Active tuberculosis can affect the lungs and may also involve other organs. A weakened immune system, including from HIV infection, can make progression from infection to disease more likely.

Arrange medical assessment for a cough that persists, coughing blood, unexplained fever, night sweats, weight loss, chest pain, or prolonged tiredness, especially after close contact with tuberculosis. Testing may include a chest image, sputum testing, or a blood or skin test depending on the situation.

If tuberculosis is diagnosed, take treatment exactly as prescribed and attend follow-up appointments. Do not share prescribed medicines. A clinician may assess household or close contacts and explain ventilation, masks, and other steps while infectiousness is being evaluated.

Seek urgent help for coughing up a large amount of blood, severe breathing difficulty, chest pain, confusion, or fainting. Contact a clinician promptly for persistent respiratory symptoms, known exposure, or symptoms in someone with reduced immunity. Early testing helps distinguish latent infection from active disease.

Ask: Which tuberculosis test do I need? Could I have latent or active infection? Do my close contacts need testing? When is it safe to return to work or school?