Tuberculosis

Microscopic image of tuberculosis

Tuberculosis (TB) is an illness caused by bacteria (germs). These bacteria spread through the air when a person with active TB in their lungs coughs, speaks, or sings. People nearby can breathe in the bacteria and become infected.

What is TB infection (latent TB infection)?

In most people, the immune system stops the bacteria from growing. The bacteria remain in the body but do not cause illness. This is called TB infection or latent TB infection.

If you have TB infection:

  • You feel well.
  • You have no symptoms.
  • You cannot spread TB to others.
  • Your TB skin test or blood test is usually positive.
  • You may become sick later if you do not receive treatment.

TB infection can be treated with antibiotics to prevent future illness.

What is TB disease?

TB disease happens when the immune system cannot stop the bacteria from growing and spreading. This usually affects the lungs but may occur anywhere in the body.

If you have TB disease:

  • You usually feel sick.
  • You may have cough, fever, night sweats or weight loss.
  • You can spread TB to others if it is in your lungs.
  • You will need to be treated with antibiotics.

TB disease in the Southeast Public Health region

If you are told you have TB disease, a public health nurse will contact you.

The nurse will:

  • Help you to take your medications.
  • Provide support if you need to isolate.
  • Follow-up with people you have been in close contact with.

All TB medicines are provided for free through Southeast Public Health.

TB Medical Surveillance (TBMS)

Some people who are new to Canada or who apply to change their immigration status must complete TB medical surveillance (TBMS). This is required by Immigration, Refugees and Citizenship Canada (IRCC).

If you have received a Medical Surveillance Form:

  • Contact the Southeast Public Health office nearest you.
  • A public health nurse will speak with you about your TBMS and help you complete the required steps.
  • Public health will notify IRCC when your TBMS is completed.

There are two tests to look for TB infection:

  • TB skin test
  • TB blood test

TB blood test

TB blood tests (also called interferon-gamma release assays or IGRAs) use a blood sample to find out if you are infected with TB germs. IGRAs are not covered under the Ontario Health Insurance Plan (OHIP).

TB skin test

The test has two steps:

Step 1:

A health-care provider puts a small amount of liquid under the skin on your lower arm.

You may have redness or itching. Do not scratch or cover it. Try putting a cold, wet cloth on it.

Step 2:

After 48 to 72 hours (two to three days), the health-care provider will check your arm and measure any swelling. People with TB infection usually have  a raised, firm bump at the test site.

You must return to have your arm looked at even if you do not see or feel anything at the test site.

Negative result

  • Usually means that you do not have TB bacteria in your body.
  • Most people do not need further testing.

Positive result

  • You may have TB bacteria in your body.
  • You will need to have a chest X-ray.
  • Your health-care provider will ask if you have symptoms like a cough.
  • More tests may be needed.
  • Your health-care provider will talk to you about treatment.
If your TB skin test is positive:
  • You should not have any more TB skin tests as they will always be positive.
  • Keep a copy of your test result.

TB skin tests are free if:

  • You were in close contact with someone with active TB.
  • You are starting medicine that weakens your immune system.
  • You are a student who needs testing for school or a placement.

Southeast Public Health notifies people who may have been exposed to TB and provides TB skin tests for people exposed to TB.

For work, volunteer, or school, testing is available at:

  • Participating health-care providers’ offices
  • Student health clinics
  • Travel clinics
  • Walk-in clinics

Do not get a TB skin test if:

  • You had a serious reaction to a TB test before.
  • You already had a positive TB skin test or TB blood test (IGRA).
  • You had TB in the past.

Talk to your health-care provider. They decide if you need other tests.