As long as you like. The procedure of yearly cxrs in PPD positive workers is archaic since if reactivation occurs, so will symptoms. It is a needless risk of radiation. Although if never done, a base line cxrs is reasonable.
My maid got a positive PPD, is there any risk of me or my family to get infected? She has normal chest X-Ray and normal blood test.
Possibly. If your doctor is worried you may have TB there are blood tests that may be useful. Read more...