Figure 2.

The effect of increasing HIV prevalence on the incidence of cases caused by reactivation (dotted line) and primary disease (solid line) (A) and on the annual risk of infection (B). As HIV prevalence increases, the number of cases of reactivation TB increases precipitously, whereas the numbers of cases of infection and primary disease rise less steeply. Thus there are fewer cases of infection and primary disease for each “source” case.