Rheumatic fever: Geography and emm types of Streptococcus pyogenes

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Simultaneously in the late 1980s, an abrupt increase in cases of acute rheumatic fever (ARF) occurred in the intermountain region of Colorado and Utah and Pittsburgh, Pennsylvania. Martin and Barbadora update the Pittsburgh experience, documenting the continued anomaly of an excessive number of new cases compared with most of the United States, as well as continued “severe” presentations. More than 60% of patients had carditis and more than 25% had chorea (with or without carditis). They also report the prospective investigation since 1995 of 84 patients and their household contacts for colonization with S. pyogenes, performing molecular typing of isolates. Few studies have done more than associate cases of ARF with predominant isolates from individuals in the community with pharyngitis. The investigators found that 36% of patients and 14% of family members tested had S. pyogenes isolated from throat cultures; isolates in a family had identical emm types and electrophoretic patterns. The authors speculate on “rheumatogenic” potential of certain strains of S. pyogenes and the usefulness of emm typing of cases and close contacts to guide research in vaccine development to prevent ARF.