Tuberculosis

What is a TB skin test? 

A TB skin test is used to see if you have ever breathed in the germs that cause TB. The TB skin test cannot tell whether TB bacteria are latent (not growing or making you sick) or active (growing and causing illness).

How is a TB skin test done?

A TB skin test is a two-part test. For the first part, a health care provider uses a tiny needle to inject a small amount of test substance called Tubersol^® under the top layer of skin on your forearm. This will make a bump that quickly goes away.

For the second part of the test, you must go back to the clinic 48 to 72 hours later to have a health care provider look at your forearm.

Your health care provider will check the area where the skin test was given for a reaction. They will measure any swelling under the skin and tell you your test result. It is important that you return to have your arm looked at, even if you feel nothing is there. People who have TB infections usually have a raised, firm bump at the site where the test was done.

What do TB skin test results mean?

A negative TB skin test usually means that you do not have TB germs in your body. Most people do not need further testing.

A positive TB skin test means you may have TB germs in your body. Your health care provider will ask you questions about your medical history and do a physical exam. You will need to have a chest x-ray. You may also be asked to do a blood test or cough up sputum (phlegm) to send for testing.

Your health care provider may send you to the TB clinic at Hotel Dieu Hospital to discuss treating your TB infection. All TB medications are provided with no cost to you.

If your TB skin test is positive you should not have any more TB skin tests. Even if you are treated for TB, any future TB skin tests you have will be positive. Be sure to keep a copy of your positive test result.

What are the possible reactions after a TB skin test?

You can expect some redness at the skin test site. The site may itch, but it is important that you do not scratch it. Scratching may cause redness or swelling, and this could make it hard for the health care provider to read the skin test accurately. If itching is a problem, put a cold, wet facecloth on the site. Do not cover the site with a bandage.

A strong reaction may cause mild pain or redness that can last for several weeks. Talk to your health care provider if you have a fever, or swelling in your arm or armpit.

There is a very small risk of a severe allergic reaction after a TB skin test. For this reason, you will be asked to stay in the clinic area for 15 minutes after the test is done.

Anyone who has had any of the following should not get a TB skin test:

• A prior allergic response or severe reaction to a TB skin test, or an allergy to anything in Tubersol^®.
• A previous positive TB skin test or TB blood test (IGRA).
• Previous active TB disease or TB infection.

If you should not be given a TB skin test, your health care provider will ask you questions about your health and decide if you need other tests for TB instead.

What is active TB disease?

TB bacteria become active if the body’s immune (defence) system cannot stop them from growing. When TB bacteria are active and growing in the body, this is called TB disease. People with active TB disease are sick. If they have TB disease of the lungs or throat, they will be able to spread the bacteria to other people. Public Health Canada has more information on active TB disease, symptoms, diagnosis, and treatment. 

Active TB disease in the KFL&A area

If you are diagnosed with TB disease, a public health nurse will contact you. The nurse will help you to manage your treatment, including taking your medications, and isolating if necessary. The nurse will work with the people you have been in contact with to check if they have been exposed to the bacteria. TB medications are provided at no cost to you.

If you have been diagnosed with TB disease but have not been contacted by KFL&A Public Health, please call the KFL&A Public Health communicable disease team at 613-549-1232, ext. 2300 as soon as possible.

Where can I get tested for TB infection?

The TB skin test is publicly funded when done for a medical reason, like when an individual:

• Has been exposed to active TB disease.
• Is starting medication that will affect the immune system.

Students entering professions where TB skin testing is required may also have their TB test publicly funded.

KFL&A Public Health provides TB skin tests for people who have been exposed to active TB disease.

KFL&A Public Health does not provide TB skin tests for work, volunteer, or school purposes. TB skin testing for these purposes can be accessed at:

• participating family doctors’ offices
• travel clinics
• student wellness services

Does the KFL&A region offer Tuberculosis Medical Surveillance?

Some people who have newly arrived or have applied for a change in immigration status in Canada may be required to have TB medical surveillance (TBMS). This is a medical check-up to look for active TB disease. It is an Immigration, Refugee and Citizenship Canada (IRCC) requirement.  

If you received a Medical Surveillance Undertaking Form when you arrived in Canada, please contact the KFL&A Public Health communicable disease team at 613-549-1232, ext. 2300. 

A public health nurse will make an appointment with you to review your TBMS paperwork. The nurse will work with you to ensure you meet the requirements for your TBMS. Once all requirements are met, the nurse will notify IRCC that you have completed your TBMS.