Tuberculosis (TB) is an infection caused by a bacterium called Mycobacterium tuberculosis. It usually affects the lungs. However, other parts of the body can also be affected, like the kidney, spine, and brain. Not everyone infected with TB gets sick.

On this page

  • Spread of Tuberculosis
  • Signs and Symptoms of Tuberculosis
  • Latent TB and TB Disease
  • Resources
  • Spread of Tuberculosis

    When someone with active TB disease of the lung coughs, sneezes, speaks, or sings, TB germs get into the air. People who share the same air space with this person may breathe in these germs. People then breathe them in and the bacteria gets in their lungs. Anyone can get TB infection. People at greater risk are family members, friends, and coworkers or schoolmates who share the same air space with the person who has TB disease of the lungs.

    Other people at increased risk include:

    • People living or working in group settings.
    • People who abuse drugs or alcohol.
    • People with medical conditions such as diabetes, HIV infection, or certain types of cancer.
    • People who are underweight.
    • People coming from countries with high rates of TB.

    Signs and Symptoms of Tuberculosis

    Signs and symptoms of TB disease depend on where in the body the TB bacteria grow. TB bacteria usually grow in the lungs. TB disease in the lungs may cause symptoms like:

    • A bad cough that lasts 3 weeks or longer
    • Pain in the chest
    • Coughing up blood or sputum (phlegm from deep inside the lungs)

    Other symptoms of TB disease include:

    • Weakness or fatigue
    • Weight loss
    • No appetite
    • Chills
    • Fever
    • Sweating at night

    Latent TB Infection and TB Disease

    Not everyone infected with TB bacteria becomes sick. In most people who breathe in TB bacteria and become infected, the body fights the bacteria to stop them from growing. These people have latent TB infection. They:

    • Have no symptoms.
    • Do not feel sick.
    • Cannot spread TB bacteria to others.
    • Usually have a positive skin or blood TB test.
    • May develop TB disease if they do not receive treatment for latent TB infection.
    • Treatment usually lasts 3 to 4 months. It is effective and safe.

    If the TB bacteria are active and able to grow, the person develops TB disease. People with active TB:

    • Have symptoms and feel sick.
    • May be able to spread the bacteria to other people.
    • Treatment usually lasts at least 6 to 12 months. It is effective and safe.

    The risk of developing TB disease is much higher for people with weakened immune systems, especially for those with HIV infection, than for people with normal immune systems.