Tuberculosis, also known as TB, is caused by bacteria that are spread from person to person through the air. TB usually affects the lungs but it can also affect lymph nodes, kidneys, bones or other body parts.

People who have active tuberculosis disease spray bacteria into the air when they cough, laugh, sneeze, talk or sigh. 

  • You can get TB if you breathe in the bacteria and it settles in your lungs or other parts of your body. 
  • You must have close, long-lasting or frequent contact with someone who has active TB disease to become infected. 
  • The bacteria that land on furniture, floors, tables or other surfaces cannot make you sick because the bacteria die quickly.

When TB bacteria are inside your body but they are not active, you have Latent Tuberculosis Infection. TB bacteria will stay inactive as long as your body’s immune system can fight them off. 

  • When you have Latent Tuberculosis Infection, you do not feel sick and cannot spread the bacteria to make others sick.
  • If your body’s immune system stops fighting the TB bacteria, they start to grow. This is called active TB disease; it can happen to anyone with Latent Tuberculosis Infection at any time.
  • Once the bacteria start to grow, they can damage the part of the body they have infected.
  • About 5 to 10% of people with Latent Tuberculosis Infection develop active TB disease in their lifetime.

The signs and symptoms of active TB disease are:

  • Coughing for more than three weeks
  • Coughing up fluid or blood
  • Fever greater than 38.3 C measured orally
  • Chest pain when you cough or breathe
  • Feeling weak and tired
  • Loss of appetite and weight loss
  • Sweating at night

A Tuberculin Skin Test, also known as TST, can tell if you have TB bacteria in your body.  This test cannot tell how long you have had the bacteria or if the TB is active (active TB disease) or inactive (Latent TB Infection).

Here are the steps for a Tuberculin Skin Test:

  1. A doctor or nurse injects a tiny amount of test fluid, called tuberculin, just under the skin of your forearm. 
  2. You can return home.  Do not touch or cover the spot where you had the injection, even if there is itching or redness. 
  3. Return to the clinic 48 to 72 hours after you had your TST.  A doctor or nurse will look at your arm to measure the spot.  Test results are sent to your doctor if necessary. The TST is generally positive if swelling the size of a dime or bigger develops at the injection site.  A positive test does not mean you are sick with active TB disease.
  4. If your test is positive, your doctor will send you for a chest x-ray to see if you have active or inactive TB.  A doctor called a radiologist reads the chest x-ray and sends the results to your doctor. 

Your doctor may recommend a sputum test to see if there are bacteria in your lungs or throat if you have symptoms of active TB disease or if your chest x-ray suggests you may have active TB disease.  If you cannot have a TST, your doctor may recommend a blood test (Interferon Gamma Release Assay, IGRA).

Public Health Services provides free Tuberculin Skin Tests only for people who have been in contact with a person who has active TB disease. 

Tuberculin skin tests for employment, school or volunteering are available for a cost at:

  • Your doctor’s office
  • Walk-in clinics
  • Employee health in your workplace
  • The student health facility at your college or university

Latent Tuberculosis Infection is treated with antibiotics.  You must take both of these every day usually for six to nine months.  These kill the TB bacteria in your body before they have a chance to become active and make you sick.

  • Talk to your doctor about treatment. 
  • Public Health Services provides treatment for Latent Tuberculosis Infection free of charge, based on a referral from your doctor.
  • After treatment, the risk of developing active TB disease is less than 1%.

Active TB disease can be cured; however, TB bacteria are very strong and hard to get rid of. You will need to take medicine every day usually for six to 12 months to kill all of the TB bacteria.

  • Public Health Services provides TB medicine free of charge.  A public health nurse visits you at home to help you take your medicine, to provide support and teaching.
  • You must take all of your medicine until your doctor tells you to stop. If you stop taking your TB medicine too soon, the TB bacteria may become stronger and harder to get rid of.

If you have active TB disease, TB bacteria are in your lungs or throat and you can spread the disease to your family and friends. Cover your mouth when you cough to prevent the bacteria from spreading.  When you have active TB disease you must stay home and away from people to stop the spread of TB to others.  Public Health Services and your doctor will tell you when it is safe to be around others.

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