Tuberculosis (TB) is an illness caused by a bacterial infection. Most people infected with TB have no sign of the disease as the bacteria are ‘sleeping’ or dormant. This is called TB infection (latent TB). Show
Some people with latent TB will develop TB disease (active TB). This can affect any part of the body but usually affects the lungs. In Australia, both active and latent TB can be treated. What is the Tuberculin Skin Test (TST)?The Tuberculin Skin Test (TST) is also known as the Mantoux Test. It is a skin test to detect if you have been infected with TB bacteria. Why is it done?The TST is done:
How is it done?A small amount of purified protein – taken from dead TB bacteria – is injected under the top layer of the skin, on the forearm.A sterile disposable needle and syringe is used to do this. A small blister will appear at the site, which will disappear within 20 minutes. There may also be a small amount of blood at the needle site. A small lump may form at the injection site over the next few days and you will need to return to your doctor or nurse 3 days later to have this assessed. The size of your lump – measured in millimetres – will indicate whether or not you have a latent TB infection. What should I do before having the TST?It is important that you tell the doctor or nurse if you:
How do I take care of the injection site?
What do the results mean?The interpretation of the results depend on a number of factors, including:
Negative resultIf the lump is below a certain size, the result of the test is negative. Usually this means that you have not been infected with TB bacteria. However, if your contact with TB was very recent, you may need to have the test repeated in 8 to 12 weeks. A false negative can occur if you are unwell, have a weak immune system, or have had a recent live vaccination. Positive resultIf the lump is above a certain size, the result of the test is positive. It means that you may have been infected with the TB bacteria. It does not mean you have TB disease (active TB). When you are infected with TB bacteria you are not infectious and you cannot pass the bacteria onto other people. You are not sick but, at some stage in the future, you may develop TB disease. If you are told your TST is positive you may be asked to see a doctor for review. What happens after I get the reading?You will be given your result when you have the reading done. If the result is negative, you may be advised that no further follow up is required. You may be recommended to have a repeat test in the future depending on why the test was initially performed. If the result is positive, you will require a chest X-ray and review by a medical officer. Some people with a latent TB will be offered medication to prevent them developing active TB. If your test is positive you may be advised not to have the test repeated. What are the possible side effects?The TST is a simple and safe test and side effects are uncommon. The side effects are mainly related to the size of the reaction and include swelling, redness and itchiness that may take a few weeks to clear. Very strong reactions are uncommon but may result in a painful swelling of several centimetres in size, blistering or ulceration. This will heal with almost no scarring. The effects of the TST are localised to the site and more general reactions are extremely rare. Make an appointment for a TST
Acknowledgements This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions. Can you shower right after a TB test?A: You can take showers and baths as you normally do.
What are the side effects of a TB test?Are there any side effects from the Mantoux skin test? Side effects are uncommon from the Mantoux skin test. However, a person who has been exposed to TB germs may occasionally have a sizable reaction, which may cause some mild itching, swelling or irritation.
Can you feel sick after a TB test?Fainting may occur after receiving this test. It may occur with other symptoms including: lightheadedness, muscle weakness, or seizures. False positive or negative tuberculin skin test reaction may occur in some patients.
How do you feel after a TB test?You may feel a slight sting. A bump or small welt will form, which usually goes away in a few hours. After 48 to 72 hours, you must return to your doctor's office. A nurse or other medical professional will check the area where you received the shot to see if you've had any reaction to the PPD.
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