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TUBERCULOSIS (TB)
TB BASICS:
Tuberculosis (often called TB) is a bacterial infection caused by a germ called Mycobacterium tuberculosis that usually affects the lungs, but can affect other parts of the body.
It is not easy to become infected with tuberculosis. Usually a person has to be close to someone with TB disease for a very long period of time. TB is usually spread between family members, close friends, and people who work or live together in closed or poorly ventilated spaces over a long period of time. Even if someone tests positive or becomes infected with tuberculosis, that does not mean they will get TB disease. Most people who become infected do not develop TB disease because their body's defenses protect them. Most active cases of TB disease result from activating old infection in people with impaired immune systems.
Great online resources of information about Tuberculosis:
New Jersey State Department of Health:
Centers for Disease Control (CDC):
MedlinePlus:
Mayo Clinic:
TESTING FOR EXPOSURE TO TUBERCULOSIS:
What is a TB or Mantoux Test?
Tuberculosis Skin Test (Mantoux or PPD Skin Test)
Excerpted from MedicineNet.com
What is the tuberculosis skin test?
The tuberculosis skin test (also known as the tuberculin test , Mantoux, or PPD test) is a test used to determine if someone has developed an immune response to the bacterium that causes tuberculosis (TB). An incubation period of two to 12 weeks is usually necessary after exposure to the TB bacteria in order for the PPD test to be positive.
How is the tuberculosis skin test administered?
The standard recommended tuberculin test, known as the
Mantoux test, is administered by injecting a 0.1 mL volume containing 5 TU (tuberculin units) PPD. The PPD is injected just beneath the surface of the skin using a very small, thin needle. A discrete, pale elevation of the skin (a wheal) 6 to 10 mm in diameter is produced. This elevation is generally quickly absorbed.
What is the method of reading the tuberculosis skin test?
"Reading" the skin test means detecting a raised area of skin reaction, referred to as induration. Induration is the key item to detect, not redness. Skin tests should be read 48 or 72 hours after the test. Tests read before 48 hours or after 72 hours are not accepted.
The diameter of the induration should be measured for a palpable, raised, hardened area around the site of injection. Again, redness is not measured.
A tuberculin reaction is classified as positive based on the diameter of the induration. In a screening test, induration greater than or equal to 15 mm is considered a positive skin test. If you have been a personal contact of someone with active TB, 10 mm of induration is considered a positive skin test. Induration of less than 2 mm ( 0-2mm) is considered a negative skin test. A person who received a BCG vaccine (administered in some countries but not the U.S.) against tuberculosis may also have a positive skin reaction to the TB test, although this is not always the case. The positive reaction that is due to the vaccine may persist for years. Those who were vaccinated after the first year of life or who had more than one dose of the vaccine have the greatest likelihood of having a persistent positive result than those who were vaccinated as infants. |
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