Figure 1.

Schematic of the disease spectrum within a study population. The large circle represents exposed children, a subset of whom will become infected with Mycobacterium tuberculosis. Of those infected, only a subset develops disease due to M. tuberculosis, and a smaller subset is confirmed microbiologically. Note that a small subset of children with microbiologic confirmation will not have active tuberculosis, as children experiencing an initial infection may have mycobacteremia, which is contained and may never develop symptoms. Also note that children with clinical symptoms consistent with tuberculosis can fall into any of the other circles, including those unexposed to tuberculosis.