Questions and Answers About TB, 2009
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Glossary of Terms Related
to TB
Active TB disease – an illness in
which TB bacteria are multiplying and attacking a part of the body,
usually the lungs. The symptoms of active TB disease include
weakness, weight loss, fever, no appetite, chills, and sweating at
night. Other symptoms of active TB disease depend on where in the
body the bacteria are growing. If active TB disease is in the lungs
(pulmonary TB), the symptoms may include a bad cough, pain in the
chest, and coughing up blood. A person with active TB disease may be
infectious and spread TB bacteria to others.
BCG – a vaccine for TB named after the
French scientists who developed it, Calmette and Guérin. BCG is
rarely used in the United States, but it is often given to infants
and small children in other countries where TB is common.
Chest x-ray – a picture of the inside
of your chest. A chest x-ray is made by exposing a film to x-rays
that pass through the chest. A doctor can look at this film to see
whether TB bacteria have damaged the lungs.
Contact – a person who has spent
time with a person with infectious TB.
Culture – a test to see whether
there are TB bacteria in your phlegm or other body fluids. This test
can take 2 to 4 weeks in most laboratories.
Directly observed therapy (DOT) –
a way of helping patients take their medicines for TB. If you get
DOT, you will meet with a health care worker every day or several
times a week. You will meet at a place you both agree on. This can
be the TB clinic, your home or work, or any other convenient
location. You will take your medicines while the health care worker
watches.
Extensively drug-resistant TB (XDR TB)
- a rare type of TB disease that is resistant to nearly all
medicines used to treat TB.
Extrapulmonary TB – active TB
disease in any part of the body other than the lungs (for example,
the kidney, spine, brain, or lymph nodes).
HIV infection – infection with the
human immunodeficiency virus, the virus that causes AIDS (acquired
immunodeficiency syndrome). A person with both latent TB infection
and HIV infection is at very high risk for active TB disease.
INH or isoniazid – a medicine used to
prevent active TB disease in people who have latent TB infection.
INH is also one of the four medicines often used to treat active TB
disease. It is considered a first-line drug.
Latent TB infection – a condition in
which TB bacteria are alive but inactive in the body. People with
latent TB infection have no symptoms, don't feel sick, can't spread
TB bacteria to others, and usually have a positive TB test. But they
may develop active TB disease if they do not receive treatment for
latent TB infection.
Multidrug-resistant TB (MDR TB) –
active TB disease caused by bacteria resistant to two of the
most important medicines: INH and RIF.
Mycobacterium tuberculosis –
bacteria that cause latent TB infection and active TB disease.
Negative – usually refers to a
test result. If you have a negative TB skin test reaction, you
probably do not have TB infection.
Positive – usually refers to a
test result. If you have a positive TB skin test reaction, you
probably have TB infection.
Pulmonary TB – active TB disease
that occurs in the lungs, usually producing a cough that lasts 3
weeks or longer. Most active TB disease is pulmonary.
Resistant bacteria – bacteria
that can no longer be killed by a certain medicine.
Rifampin (RIF) – one of the four
medicines often used to treat active TB disease. It is considered a
first-line drug.
Smear – a test to see whether there
are TB bacteria in your phlegm (sputum). To do this test, lab
workers smear the sputum on a glass slide, stain the slide with a
special stain, and look for any TB bacteria on the slide. This test
usually takes 1 day to get the results.
Sputum – phlegm coughed up from deep
inside the lungs. Sputum is examined for TB bacteria using a smear;
part of the sputum can also be used to do a culture.
TB skin test – a test that is often
used to detect latent TB infection. A liquid called tuberculin is
injected under the skin on the lower part of your arm. If you have
a positive reaction to this test, you probably have latent TB infection.
TB Blood Test – a new test that
uses a blood sample to find out if you are infected with TB
bacteria. The test measures the response to TB proteins when they
are mixed with a small amount of blood. Examples of these special TB
blood tests include QuantiFERON®-TB
Gold (QFT-G) and T-Spot®.TB test.
Tuberculin or PPD – a
liquid that is injected under the skin on the lower part of your arm
during a TB skin test. If you have TB infection, you will probably
have a positive reaction to the tuberculin.
Last Modified: 02/10/2009
Last Reviewed: 05/18/2008 Content Source: Division of Tuberculosis Elimination
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
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