Tuberculosis Test

Tuberculosis is an infectious disease that most commonly affects the lungs. The Tuberculosis skin test can show if you have been exposed to the organism that causes tuberculosis. The skin test involves injecting a small amount of fluid under the skin of the forearm. This fluid contains a protein derived from the organism causing tuberculosis and is harmless to your body.

The site of the skin test must be examined by a health professional within 48 – 72 hours to determine the result of the test. It will be necessary to repeat the test if you are not examined within this 72-hour period. Redness may occur at the test site and does not indicate a positive test. Any swelling (also called an induration) that is present will be measured by a health professional who will determine if this indicates a positive or negative test.

A positive skin test does NOT mean that you have active tuberculosis; rather, that you may have been exposed to the tuberculosis organisms at some time in the past. If the result of the skin test is positive, a chest x-ray must be obtained to determine whether there is any active disease. A physician or trained health professional will review your history, order further tests if necessary, and talk to you about future recommendations.

The importance of the skin test is that it shows if you have been exposed to tuberculosis; it helps determine if you are at risk for developing the disease and if so, treatment recommendations can be provided before you become sick.

WHY DO I NEED THE TUBERCULOSIS SKIN TEST IF I HAVE HAD THE BCG VACCINE?
In order to maintain a healthy environment for students, faculty and staff, the University of Illinois seeks to assure that the campus is free from tuberculosis. Because different countries have different standards of testing and evaluating for this disease, the University requires that the student health center test all incoming international students for TB.

Many individuals who grew up in countries other than the United States or Canada have received the BCG (Bacille Calmette-Guerin) vaccine against tuberculosis. Studies have shown, however, that although some people are protected by this vaccine, many are either not protected at all, or immune for only a short time.

If you have a positive reaction to the TB skin test and have received BCG, the physician at your follow-up appointment will consider certain factors such as the extent of the reaction, whether you come from a country with a high incidence of TB, whether you have had contact with a person with active TB, and/or how many doses of BCG you have received. He/she will then advise you on what to do next.

Tuberculosis testing is performed in the Immunization and Travel Clinic during walk-in hours: Monday through Wednesday, 8:30 a.m. - 4:30 p.m. and Friday, 8:30 a.m. - 4:30 p.m. (Note: No testing is done on Thursday).

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