Figure 2.

Model summarizing changes in group A Streptococcus (subclone M3) over time. The frequency distribution of all strains in the three epidemics is shown in grey, with three peaks of infection centred around 1995, 2000 and 2005. Ten major subclones (SC‐1 to SC‐10) were identified among the 344 strains collected from 1992 through 2007 based on different DNA‐typing techniques. The widths of the coloured SC symbols show the temporal distribution of the SCs, and the heights are proportional to the annual abundance. Arrows between SCs indicate estimated relationships and give differences found in the loci assessed. The total number of isolates per year is given above the time line at the bottom. Reprinted from Beres and colleagues (2010). Copyright of the National Academy of Sciences.