A skin test is a simple test, often called a Mantoux skin test, or tuberculin skin test (TST), done to find out if you have been infected with the tuberculosis (TB) bacteria. You cannot get TB from having the skin test done.
You should be tested if you:
If you need yearly skin testing, you may be asked to have the skin test repeated one to three weeks later. This is called a "two-step" skin test, and is required only once in a person's lifetime. It is a more accurate way to determine if you have been infected in the past. Be sure to keep documentation of your test so you don't need to have a "two-step" skin test repeated.
If you are a contact of a case of infectious TB you will need to have the skin test repeated 8 weeks after your last exposure to the infected person.
A small amount of the test liquid is placed by needle just under the skin of the forearm. This makes a little bump that goes away quickly. Two or three days later, the same doctor or nurse who gave you the test should look at your arm. If nothing is there, the test is negative. If there is swelling, the doctor or nurse will measure it and decide if the test is positive. The result is then recorded. It is important that you return to have your arm looked at, even if you feel nothing is there.
A positive skin test result means you may have been infected with the TB bacteria or other similar bacteria.
You will need to see your doctor to determine if you have latent or active TB disease. He or she will take a medical history and perform a physical exam. You will be sent for a chest x-ray. You may be asked to start medication to prevent TB disease.
Remember: a positive skin test means you have a small (5 to 10 percent) risk of developing TB disease in your lifetime.
If you are healthy, (i.e. no symptoms of persistent cough, fever, fatigue, night sweats, loss of appetite, or weight loss) you are unlikely to have TB disease or be infectious. A positive skin test does not mean you have active TB disease.
The test area of your arm may be itchy and sore for a while if you have a very strong positive reaction. In rare cases, the skin may break down where the test was done or leave a scar.
You can have the test done at your doctor's office or some walk-in clinics. KFL&A Public Health only does TB skin tests for contacts of an active case of TB disease.
If you have any questions, please call the Communicable Disease team at 613-549-1232 or
1-800-267-7875, ext. 1287, or visit our website at www.kflapublichealth.ca.
Revised: 2013-02-25