Glossary of Terms Related to TB

BCG - a vaccine for TB named after the French scientists Calmette and Guérin.  BCG is not widely used in the United States, but is often given to infants and small children in other countries where TB is common.

Cavity - a hole in the lung where TB bacteria have eaten away the surrounding tissue.  If a cavity shows up on your chest x-ray, you are more likely to cough up bacteria and be infectious.

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 your chest.   A doctor can look at this film to see whether TB bacteria have damaged your 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 medicine 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 medicine at this place.

Extrapulmonary TB - TB disease in any part of the body other than the lungs (for example, the kidney or lymph nodes).

HIV infection - infection with the human immunodeficiency virus, the virus that causes AIDS (acquired immunodeficiency syndrome).  A person with both TB infection and HIV infection is at very high risk for TB disease.

Infectious TB - TB disease of the lungs or throat, which can be spread to other people.

Infectious person - a person who can spread TB to others because he or she is coughing TB bacteria into the air.

INH or isoniazid - a drug used to prevent TB disease in people who have TB infection.  INH is also one of the five drugs often used to treat TB disease.

Miliary TB - TB disease that has spread to the whole body through the bloodstream.

Multidrug-resistant TB (MDR TB) - TB disease caused by bacteria resistant to more than one drug often used to treat TB.

M. tuberculosis - bacteria that cause TB infection and TB disease.

Negative - if you have a negative TB skin test reaction, you probably do not have TB infection.

Positive - if you have a positive TB skin test reaction, you probably have TB infection.

Preventive therapy - treatment for people with TB infection that prevents them from developing TB disease.

Pulmonary TB - TB disease that occurs in the lungs, usually producing a cough that lasts longer than 2 weeks.  Most TB disease is pulmonary.

Resistant bacteria - bacteria that can no longer be killed by a certain drug.

TB skin test - a test that is often used to detect 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 TB infection.

Smear - a test to see whether there are TB bacteria in your phlegm.  To do this test, lab workers smear phlegm 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.

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 infection - a condition in which TB bacteria are alive but inactive in the body.  People with TB infection have no symptoms, don't feel sick, can't spread TB to others, and usually have a positive skin test reaction.  They may develop TB disease later in life if they do not receive preventive therapy.

TB disease - an illness in which TB bacteria are multiplying and attacking different parts of the body.  The symptoms of TB disease include weakness, weight loss, fever, no appetite, chills, and sweating at night.   Other symptoms of TB disease depend on where in the body the bacteria are growing.   If TB disease is in the lungs (pulmonary TB), the symptoms may include a bad cough, pain in the chest, and coughing up blood.

Tuberculin - 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.

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