TB SKIN TESTING (TST)

TB, or tuberculosis, is caused by the bacteria Mycobacterium tuberculosis. It is spread through the air when a contagious person coughs, sneezes, sings or talks. TB usually occurs in the lungs but can affect any organ.

There are two types of TB infections. The first is called latent TB infection, which occurs when a person inhales TB bacteria, but the immune system prevents the bacteria from multiplying, so there are no symptoms and the infection is not contagious. People with latent TB may not even know they are infected. In contrast, the second type called active TB disease occurs when the immune system fails to stop the bacteria from multiplying, leading to illness and a highly contagious condition. Those at higher risk of developing active TB include individuals with HIV, those recently infected with TB, babies, young children, people who inject drugs, the immunocompromised, the elderly, and those who were inadequately treated for past TB infections.

TB can still be present in latent form, where individuals carry the bacteria without showing symptoms, and it can become active later, especially in people with weakened immune systems. Early detection through testing is crucial for preventing the spread of active TB, which is highly contagious and can lead to severe illness if not treated. Testing helps protect vulnerable populations, control outbreaks, and prevent the reemergence of TB in areas where it is less prevalent.

The TB test consists of two appointments:

• Appointment #1: A small amount (0.1 mL) of Tubersol is injected under the first layer of skin on your forearm. If you have been exposed to TB bacteria your skin will react to form a firm red bump.
• Appointment #2: You must return to the clinic 48 to 72 hrs later to have your forearm looked at by the nurse. If it is not looked at within 72 hours the result becomes invalid and the test must be repeated. Amani Health Services will provide a test result card at your second appointment after the test has been read.

You will need to bring:

• Paperwork from your school or employer, if required. If there is no paperwork from your school or employer, Amani Health Services will provide a test result card.
• BC Care Card (if you have one).

You shouldn't get the test if any of the following apply to you:

• Previous allergic reaction, severe reaction (such as blistering), or allergy to any Tubersol component.
• Proof of an earlier positive TST result.
• Interferon Gamma Release Assay (IGRAs) reacted in the past (TB blood test).
• LTBI or prior active TB illness.
• If you had the BCG vaccine and you have a choice of having a TB blood test or a TB skin test, it is better for you to have the TB blood test. This is because the TB blood test is not affected by the BCG vaccine. This means that your TB blood test will be “positive” only if you have TB germs in your body.

If you should not get a TST, then your health care provider will ask you questions about your health and decide if you need other TB tests instead.

Note: If you have received a live vaccine prior to undergoing a TB test, you must wait 28 days from the date of the vaccination before the TB test can be administered.