Tuberculosis (TB)

image of lungs

What is tuberculosis (TB)?

Tuberculosis (TB) is a disease caused by bacteria called mycobacterium tuberculosis.

The bacteria enter the body through air you breathe and causes an infection, usually in the lungs. Sometimes infections can happen in other parts of the body.

When the bacteria are dormant (asleep), people do not have active TB disease. This is called latent TB infection. These bacteria are not making you sick at this time, and you cannot pass the bacteria to other people.

Active TB disease occurs when bacteria multiply, causing damage to the lungs or other parts of the body, such as the brain, lymph nodes, or kidneys. People with active TB disease may pass the bacteria to others.

What are the symptoms of TB?

  • Coughing that lasts three or more weeks
  • Chest pain or pain with breathing or coughing
  • Loss of appetite
  • Chills
  • Unintentional weight loss
  • Fatigue
  • Night sweats
  • Fever
  • Coughing up blood

Symptoms vary depending on where the bacteria are growing in the body.  For example, if the lymph nodes or joints are infected, you may experience swollen lymph nodes or joint pain. 

How does TB spread?

  • Spread from person to person through the air.
  • When someone with active TB disease in the lungs speaks, coughs, or sneezes.
  • Close, prolonged, or regular contact with someone who is sick with active TB disease is needed to spread this disease.
  • People with latent TB infection (LTBI) cannot spread TB bacteria to others.

How do you test for TB?

Screening for TB is done by a tuberculin skin test (TST) [1] or an Interferon-Gamma Release Assay (IGRA) [2]  blood test.

A TB skin test shows if you have been exposed to the TB bacteria and have it in your body. It is not a vaccine. A TST is safe during pregnancy. You can still have a test if you had a Bacille CalmetteGuérin (BCG) vaccine in the past.

The BCG vaccine is not routinely given in Canada, but it is often given to infants and small children in other countries with high rates of TB. The vaccine becomes less effective over time. You can still be infected with TB even if you have received the BCG vaccine.

Your health care provider may recommend one or both tests. A positive TST or IGRA result means a person has the TB bacteria in their body. A physical exam and chest x-ray are needed to check for TB disease; further testing may also be needed.

Who should be tested?

TB can affect anyone regardless of age, gender, ethnicity, or race but some people are at greater risk. Health care workers and people who have lived, worked, or travelled to areas that have high TB rates should speak to their health care provider or contact the Health Unit for more information.

How is TB treated?

People with LTBI may benefit from medicine to prevent active TB disease.  People with active TB disease must complete treatment to cure the disease.  All TB treatment is free from the Health Unit with a script from a health care provider.

For more information contact the Health Unit or speak to your health care provider.


The Canadian Thoracic Society and the Public Health Agency of Canada. (2022). Canadian Tuberculosis Standards. (8th ed.). Ottawa