What is tuberculosis?
Tuberculosis, or TB, is primarily an airborne disease caused by
the bacteria, M. tuberculosis. The bacteria are spread
through the air and usually infect the lungs, but can also infect
other parts of the body as well.
One-third of the world's population, nearly 2 billion
people, is infected with M. tuberculosis, the TB
bacterium. Although TB was once the leading cause of death in the
United States, cases of TB declined rapidly in the 1940s and 1950s,
once scientists discovered the first of several drugs used to treat
the disease. Today, the incidence of TB in the US is the lowest
ever. However, case rates among foreign born persons living in the
US now accounts for most of the reported cases.
TB can be spread when a person with active pulmonary TB disease
coughs, sneezes, talks, sings or laughs. Only people with an active
pulmonary infection are contagious. Most people who breathe in TB
bacteria are able to fight the bacteria and stop it from growing.
The bacterium becomes inactive in these individuals, and is
referred to as a latent TB infection. Approximately 10% of the US
population has latent infection.
Although the bacteria are inactive, they still remain alive in
the body, and can become active later. Some people can have a
latent TB infection for a lifetime, without it ever becoming active
and developing into TB disease. However, TB can become active if
the immune system becomes weakened and cannot stop them from
growing. This is when the latent TB infection becomes a TB
disease.
What are the symptoms of TB?
Those people with inactive TB do not exhibit symptoms; however,
they may have a positive skin reaction test. The tuberculin skin
test has low specificity but three are newer tests that are more
specific for M. tuberculosis. The CDC has recently established
guidelines for these new blood tests.
Those with TB disease, however, can exhibit any of the following
symptoms:
- Bad cough (lasting longer than 2 weeks)
- Pain in the chest
- Coughing up blood or sputum
- Fatigue or weakness
- Loss of appetite
- Weight loss
- Chills
- Fevers
- Night sweats
How do I know if I should get tested for TB?
If you feel that you should be tested, a skin test will
determine if you have a latent TB infection. There is also a blood
test available to determine infection with TB. You should consider
a skin test or blood test if: