Figure 1.

Canada-wide expansion of emm74 group A Streptococcus invasive disease. A, Isolation of invasive group A Streptococcus (iGAS) isolates in all Canadian provinces and territories from January 2012 to June 2017. Bars show emm type distribution as a percentage of the total number of isolates in each year (first 6 months for year 2017). The percentage of emm74 iGAS isolates, which were rarely seen in Canada, strikingly increased starting in 2015, spiked in 2016, and continued to be isolated in high numbers by June 2017, causing thus far more than 160 invasive cases in several Canadian provinces. B, Geographical origin and temporal distribution of 168 emm74 isolates recovered in Canada from individual patients with emm74 iGAS disease. For the period 2012 to 2014, only 2 emm74 iGAS cases were recorded in Canada, 1 in the province of Alberta (May 2012) and 1 in the province of Ontario (January 2013). No further emm74 invasive disease cases were observed until 2 years later, when 2 emm74 iGAS strains were isolated in Saskatchewan during the second quarter of 2015. Then, beginning in late 2015 and continuing to June 2017, increasing numbers of emm74 iGAS were isolated in the provinces of British Columbia, Ontario, Alberta, and Quebec.