Given tuberculous infection, the risk of progression to tuberculosis for an individual may vary hugely as shown in this selection of risk factors.
An infection acquired a long time ago may carry a risk of about 1 in 1,000 person years. Recently acquired infection increased the risk ten-fold, and an HIV infection superimposed on a pre-existing tuberculous infection a hundredfold. It is not known how much exactly, but conceivable that an HIV infection preceding acquisition of tuberculous infection may carry a risk of progression in excess of 70%.
