Environmental Health & Safety
Tuberculosis (tb) Information
What is TB?
TB is an infectious disease caused by a germ called mycobacterium tuberculosis
that usually affects the lungs (other parts of the body such as the brain or
spine may also be affected). The disease spreads when an infected person coughs,
sneezes, etc., causing germs to enter the air. People who breath these germs
into their lungs may become infected.
What is the prevalence of TB?
About 8 million new cases a year occur worldwide. In the United States over 25,000
new cases are reported annually. In addition, it is estimated that 10-15 million
people in the US are asymptomatically infected with TB, with the potential to
develop active disease. However, even if infected, only 10% of people develop
active TB.
What are the symptoms of TB?
General symptoms may include feeling weak or sick, weight loss, fever, and/or
night sweats. Symptoms of TB of the lungs may include cough, chest pain, and/or
coughing up blood; depending on other parts of the body, which may be affected
symptoms will vary.
How can I tell if I have TB?
The tuberculin skin test can identify most people infected with tubercle bacillus
six to eight weeks following initial exposure. A substance called purified protein
derivative (PPD) is injected under the skin of the forearm and is examined 48-72
hours later. At TSRI all "employees" are eligible to participate in
the initial and annual TB screening program free of charge.
What if the test results are negative for TB?
A negative test usually means that a person is not infected, but it is possible
for the test to be "false negative." If this is your first ever TB
test, it is recommended that you have a repeat TB test 1-10 weeks following your
initial test. If you have been tested previously, it is recommended that you
be tested annually.
What if the test results are positive for TB?
A positive TB skin test indicates that you have been infected with the TB germ;
it does not necessarily mean that you have the disease. In general, a positive
TB test will be followed up with a chest x-ray.
If the x-ray is normal (no evidence of TB in the lung), your are infected
with TB but not "sick." If this is the case, you will most likely be
treated with antibiotics. This medication kills the TB germs so you will not
get sick as a result of the TB germs. It is important that the medication be
taken for the duration prescribed (usually 6-12 months). If the x-ray is abnormal,
other tests may be ordered and the physician will develop a treatment plan.
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