Figure 3. The mumps outbreak in Washington was seeded by approximately 13 introductions.

(a) We separated each introduction into Washington inferred on the maximum clade credibility tree (Figure 2) and plotted them independently. Large, colored dots represent the inferred geographic location that the Washington introduction was seeded from. Branches that extend further back in time than April 2016 (approximately 6 months prior to the first reported case in Washington) are dotted to represent that transmission likely occurred via other, unsampled locations. The nine tips at the very top without inferred geographic ancestry represent the highly divergent nine Washington genomes with a TMRCA of ~22 years that are highlighted in Figure 2—figure supplement 3 and shown in Figure 2. For reference, the cumulative case counts from Arkansas and Washington are plotted below. (b) For each tree in the posterior set, we inferred the number of introductions into Washington. We plot the proportion of trees in the posterior set in which that number of introductions was inferred.