Figure 1.

Study design. The figure illustrates the screening of a household with four contacts over the yearlong follow-up period. Each row illustrates a different individual, and an arrow connects successive observations. White circles with solid outline indicate no tuberculosis (TB) infection, white circles with dashed outline indicate latent TB infection (LTBI), and black circles indicate incident TB disease between screenings. The top case is coprevalent for TB disease with the household index case (not pictured) and not included in future screenings. The second row illustrates that individuals with a positive tuberculin skin test at any observation are not screened on successive observations, and the third row shows that individuals with a positive tuberculin skin test are still screened for active TB. The bottom row shows that individuals with neither LTBI nor TB disease at their previous observation are screened for LTBI at each successive observation.