Testing for TB
What is TB?
“TB” is short for a disease called tuberculosis. TB is spread through the air from one person to another. TB germs are passed through the air when someone who is sick with TB disease of the lungs or throat coughs, speaks, laughs, sings, or sneezes. Anyone near the sick person with TB disease can breathe TB germs into their lungs.
TB germs can live in your body without making you sick. This is called latent TB infection. This means you have only inactive (sleeping) TB germs in your body. The inactive germs cannot be passed on to anyone else. However, if these germs wake up or become active in your body and multiply, you will get sick with TB disease.
When TB germs are active (multiplying in your body), this is called TB disease. These germs usually attack the lungs. They can also attack other parts of the body, such as, the kidneys, brain, or spine. TB disease will make you sick. People with TB disease may spread the germs to people they spend time with every day.
How do I know if I have been infected with TB germs?
If you have been around someone who has TB disease, you should go to your doctor or your local health department for tests.
There are two tests that can be used to help detect TB infection: a TB skin test or a TB blood test. The skin test is used most often. A small needle is used to put some testing material, called tuberculin, under the skin. In 2-3 days, you return to the health care worker who will check to see if there is a reaction to the test. In some cases, a TB blood test is used to test for TB infection. This blood test measures how a person’s immune system reacts to the germs that cause TB.
To tell if someone has TB disease, other tests such as chest x-ray and a sample of sputum (phlegm that is coughed up from deep in the lungs) may be needed.
Note: Tell your health care worker if you have ever had a “positive” reaction to a TB skin test or TB blood test, or if you have been treated with TB drugs in the past.
- Page last reviewed: October 26, 2014
- Page last updated: November 21, 2014
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