PIGG and rheumatic fever: It is noteworthy that the emm18 (100% SpeB-non-producers) and emm3 (50% SpeB-non-producers) organisms recovered from the URT in this study (i.e., pharyngitis and ARF-associated combined; S1 Table) represent emm types that were highly prevalent in ARF outbreaks within the United States during the 1980s [38, 39].