How do ppd shots work

Most people with a positive TB skin test have latent TB infection. To be sure, your doctor will examine you and give you a chest x-ray. You may need other tests to see if you have active TB disease. The TB Tuberculosis Skin Test Mantoux This fact sheet gives information about how the skin test is given and read, and what the results mean. What is latent TB infection?

This phase can last for a very long time — even many years. TB germs are active and spreading. They are damaging tissue in your body. Your chest x-ray is usually normal. You usually feel sick. Your doctor will do special tests to find where TB is harming your body. You can't spread TB to other people. This situation is called latent TB. Most people in the United States who are infected with the bacteria do not have signs or symptoms of active TB. With a negative reaction, the skin where you received the PPD test is not swollen, or the swelling is very small.

This measurement is different for children, people with HIV, and other high-risk groups. The PPD skin test is not a perfect screening test. A few people infected with the bacteria that cause TB may not have a reaction.

Also, diseases or medicines that weaken the immune system may cause a false-negative result. An abnormal positive result means you have been infected with the bacteria that cause TB. You may need treatment to lower the risk of the disease coming back reactivation of the disease.

A positive skin test does not mean that a person has active TB. More tests must be done to check whether there is active disease. In people with no known risks of TB, 15 mm or more of firm swelling at the site indicates a positive reaction. People who were born outside the United States who have had a vaccine called BCG may have a false-positive test result. Factors in selecting which test to use include the reason for testing, test availability, and cost.

Generally, it is not recommended to test a person with both a TB skin test and a TB blood test. A TB skin test requires two visits with a health care provider. On the first visit the test is placed; on the second visit the health care provider reads the test. Additional tests are needed to determine if the person has latent TB infection or TB disease.

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How do you read a TB skin test? Medically reviewed by Jill Seladi-Schulman, Ph. What to expect Results Takeaway The purified protein derivative test confirms whether someone has had exposure to tuberculosis, a serious infectious disease. What to expect. Exposure to air pollutants may amplify risk for depression in healthy individuals. Costs associated with obesity may account for 3.