The main way to avoid infection with the bacteria that cause TB is to avoid exposure to people with active disease.
There is a vaccine for TB, called the BCG vaccine (named after the French scientists who developed it, Calmette and Guérin; the B is for bacillus). BCG is often administered to infants and small children in countries where TB is common. It is not usually not given in countries where TB is less common, such as the United States, because it does not protect adults very well against the disease and because it interferes with the results of TB skin tests. Though it is not perfect, the BCG vaccine does offer protection from the most serious forms of the disease in young children.
Many people who receive the BCG vaccination will have a positive TB skin test for the rest of their lives.
If you have a latent TB infection, you will need to take medicine to ensure that it does not turn into active TB disease.
People with a positive tuberculin skin test may or may not receive preventive medication therapy. This will depend on the exposure history, the timing of the skin test conversion (when the test changes from negative to positive) and other factors in the person's medical history.
When it is known that a person has recently been in close contact with someone with active tuberculosis and has developed a positive tuberculin skin test or TB blood test, preventive treatment is advisable. This is due to a high risk of developing active disease. INH (Isoniazid) may be prescribed for nine months as preventive treatment.
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