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What is tuberculosis (TB)?

Tuberculosis (TB) is an infection caused by bacteria (germs) called mycobacterium tuberculosis complex.  These germs usually attack the lungs, but can affect any part of the body.  TB occurs worldwide and has been around for centuries.

What are the symptoms of TB?

Lady coughing

There are two forms of TB:

  1. Latent TB infection (LTBI):  Most people who breathe in the TB germs are able to stop them from growing.  The immune system traps the germs and keeps them inactive.  This is called LTBI.  These people have a positive skin test or blood test, but do not feel sick and have no symptoms.  They may develop active TB disease later in life.
  2. Active TB disease:  TB germs become active when the body’s immune system cannot stop the germs from growing.  The active TB germs begin to grow and cause damage to the body.  Symptoms of TB include:
    • Cough (lasting longer than 3 weeks)
    • Fever/chills/night sweats
    • Feeling tired
    • Unexplained weight loss/loss of appetite

Symptoms vary depending on where the germs 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?

TB is spread from person to person through the air.  TB is spread when someone with active TB disease in the lungs speaks, coughs or sneezes.  It is not highly contagious.  Close, prolonged or regular contact with someone who is sick with active TB disease is needed to spread this disease.  People with LTBI cannot spread TB germs to others.

How do you test for TB?

Screening for TB is done by a tuberculin skin test (TST) or an Interferon-Gamma Release Assay (IGRA) blood test.  Your health care provider may recommend one or both of these tests. A positive TST or IGRA result means a person has the TB germ in their body.  A physical exam and chest x-ray are needed to check for TB disease; further testing may also be needed.

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.

Adapted with permission from Toronto Public Health.


The Canadian Thoracic Society and the Public Health Agency of Canada. (2013). Canadian Tuberculosis Standards. (7th ed.). Ottawa

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