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A tuberculosis infection may result after close contact with a person who has tuberculosis (TB).
Tuberculosis infection is determined by a significant reaction to the Mantoux skin test with no symptoms of TB, and no TB bacteria found in the sputum.
Tuberculosis disease is characterized by the appearance of TB symptoms, a significant reaction to the Mantoux skin test, and TB bacteria found in the sputum.
Tuberculosis may last for a lifetime as an infection, never developing into a disease. However, individuals with TB infection are at considerable risk of developing TB disease, particularly during the first year after acquiring the infection. Individuals with weakened immune systems, such as people with HIV, are at high risk of developing TB disease if the TB infection is untreated.
To spread the TB bacteria, a person must have TB disease. Having a TB infection is not enough to spread the bacteria.