Health Topics


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 other parts of the body, such as the bones, brain and kidneys. People who have TB 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 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.
  • A TB Skin Test or IGRA (Interferon Gamma Release Assay  blood test) will let you know if you have TB infection in your body
  • Watch TB personal stories

Latent TB Infection

  • When TB bacteria are inside your body but they are not growing, you have Latent Tuberculosis Infection. Usually TB bacteria will stay inactive as long as your body’s immune system can fight them off.
  • When you have Latent TB Infection, you do not feel sick and cannot spread the bacteria to make others sick.
  • About 5 to 10% of people with Latent TB Infection develop TB disease in their lifetime.

TB Disease

  • If your body’s immune system stops fighting the TB bacteria, they start to grow (bacteria increase in numbers). This is called TB disease; it can happen to anyone with Latent TB Infection at any time.
  • Once the bacteria start to grow, they can damage the part of the body they have infected.
  • The signs and symptoms of TB disease are:
  • Coughing for more than three weeks
  • Feeling weak and tired
  • Loss of appetite and weight loss
  • Sweating at night
  • Coughing up fluid or blood
  • Fever greater than 38.3 C measured orally
  • Chest pain when you cough or breathe
A Person with Latent TB Infection A Person with TB Disease
  • Has no symptoms
  • Usually has symptoms that may include
    • a bad cough that lasts 3 weeks or longer
    • pain in the chest
    • coughing up blood or sputum
    • weakness or fatigue
    • weight loss
    • no appetite
    • chills
    • fever
    • sweating at night
  • Does not feel sick
  • Usually feels sick
  • Cannot spread TB bacteria to others
  • May spread TB bacteria to others
  • Usually has a skin test or blood test result indicating TB infection
  • Usually has a skin test or blood test result indicating TB infection
  • Has a normal chest x-ray and a negative sputum smear
  • May have an abnormal chest x-ray, or positive sputum smear or culture
  • Needs treatment with antibiotics for latent TB infection to prevent TB disease for four to nine months
    • Antibiotics kill the TB bacteria in your body before they have a chance to grow and make you sick.
    • Public Health Services provides treatment for latent tuberculosis infection free of charge
    • After treatment, the risk of developing TB disease is about less than 1%.
  • Needs treatment with antibiotics for TB disease for six to twelve months.
    • TB disease can be cured; however, TB bacteria are very strong and hard to get rid of.
    • Public Health Services provides treatment for TB disease free of charge.  

A TB Skin Test 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 bacteria is growing (TB disease) or not growing (Latent TB Infection). If you cannot have a TB Skin Test, your doctor may recommend a blood test (Interferon Gamma Release Assay - IGRA).

Steps for a TB 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 TB Skin Test.  A doctor or nurse will measure the area. The TB Skin Test is usually positive if swelling the size of a dime or bigger develops at the area. A positive test does not mean you are sick with TB disease.

Where can I get a TB Skin Test in Hamilton?

Public Health Services provides free TB Skin Test only for people who have been named as a contact with a person who has TB disease. 

TB Skin Test are available at:

TB Skin Tests are covered under the Ontario Health Insurance Plan (OHIP) for:

  • People who are named as a contact of a TB case.
  • People who need a TB Skin Test for medical reasons
  • People who have recently immigrated from countries where TB is more common.
  • People who require  a  TB Skin Test for admission  to a daycare, pre-school program or a school, community college, university or other educational institution or program (including a work placement that the program may require)
  • People who are 65 years of age or younger and need to be admitted to a Long Term Care Facility
  • OHIP does not cover the cost of TB Skin Tests that are needed for employment or volunteer purposes.

IGRA is a blood test called Interferon Gamma Release Assay that can be used to see if a person has the TB bacteria in their body. IGRA is not covered under the Ontario health insurance plan (OHIP).

  • A positive skin test / IGRA shows you have TB infection. More tests will be needed to make sure the TB bacteria is not growing. These tests usually include a check-up by a health care provider for signs and symptoms of TB disease and a chest x-ray
  • Your doctor may recommend a sputum test to see if there are bacteria in your lungs or throat, if you have symptoms of TB disease or if your chest x-ray suggests you may have TB disease.  
  • Once your family doctor tells you that you do not have TB disease, ask about medication to prevent getting TB disease in the future. This medication is free of charge through Public Health Services.

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