Figure 3. Algorithm based on decision-tree analysis for predicting TB outbreaks.

Algorithm based on data available at time the TB cluster contained 3 cases. Decision-tree analysis categorizes clusters in high-, medium-, or low-risk groups. Clusters in the high-risk group are considered of greatest priority for early interventions, such as intensive contact investigations. Although clusters in medium- and low-risk groups may not be considered highest priority when they have 3 cases, they can be re-evaluated should additional cases occur.