Slide 57 of 68
Notes:
The initial infection may go unnoticed, and it can take from 4-12 weeks after exposure to a person with TB for the PPD skin test to be positive. However, when a person develops active TB, the symptoms usually are chronic, meaning that they last longer than four weeks. Active disease is most likely to occur in the first two years after conversion from a negative to a positive PPD.
Once a person has been diagnosed with TB in the lung, they are considered infectious until their sputum no longer shows the TB organism (3 negative AFB smears, at least 24 hours apart).
