What is tuberculosis?

Tuberculosis (TB) is a bacterial infection that most often affects the lungs, but can sometimes affect other parts of the body. There are two stages of TB: infection and active disease.

TB is spread from person to person through the air when a person with TB disease coughs or sneezes.


People with TB infection do not have any symptoms. Common symptoms of active TB disease include:

  • cough
  • fever
  • weakness
  • night sweats
  • feeling very tired
  • loss of appetite
  • weight loss


TB is usually diagnosed with a skin test. During this test, a small amount of testing fluid is injected just under the skin. If a certain kind of bump develops after two to three days, the test may be positive for TB infection.


If your child has TB infection, he or she will need to take medication to keep from developing active TB disease. It takes about six to nine months for the medicine to kill the TB germs.

If your child has TB disease, he or she will need to take several different medications to kill all of the germs.

Learn more about Pediatric Pulmonology, Allergy, Immunology and Sleep services at Boston Children’s Health Physicians.