Although your body may harbor the bacteria that cause tuberculosis, your immune system usually can prevent you from becoming sick. For this reason, doctors make a distinction between:

  • Latent TB. In this condition, you have a TB infection, but the bacteria remain in your body in an inactive state and cause no symptoms. Latent TB, also called inactive TB or TB infection, isn't contagious. However, it can turn into active TB, so treatment is important for the person with latent TB and to help control the spread of TB in general. An estimated one-third of the world's population has latent TB.
  • Active TB. This condition makes you sick and can spread to others. It can occur in the first few weeks after infection with the TB bacteria, or it might occur years later.

Signs and symptoms of active TB include:

  • Cough
  • Unintentional weight loss
  • Fatigue
  • Fever
  • Night sweats
  • Chills
  • Loss of appetite

What organs are affected?

Tuberculosis usually attacks your lungs. Signs and symptoms of TB of the lungs include:

  • Coughing that lasts three or more weeks
  • Coughing up blood or sputum
  • Chest pain, or pain with breathing or coughing

Tuberculosis can also affect other parts of your body, including your kidneys, spine or brain. When TB occurs outside your lungs, signs and symptoms vary according to the organs involved. For example, tuberculosis of the spine may give you back pain, and tuberculosis in your kidneys might cause blood in your urine.

When to see a doctor

See your doctor if you have a fever, unexplained weight loss, drenching night sweats or a persistent cough. These are often signs of TB, but they can also result from other medical problems. Your doctor can perform tests to help determine the cause.

Jan. 26, 2013