Rheumatic Fever

Acute rheumatic fever (ARF) is a delayed, immune-mediated complication of group A Streptococcus (GAS) pharyngitis. It is not an infection spreading from the throat to the heart or joints. Manifestations usually begin about 2 to 4 weeks after an untreated throat infection, when the organism is typically no longer present in the injured tissues. The mechanism is molecular mimicry. Antibodies and T cells directed against GAS M protein and group A carbohydrate epitopes can cross-react with human cardiac myosin, valve endothelium, synovium, and basal-ganglia antigens. The result is inflammation in several tissues at once. The valve injury matters most over time: recurrent valvulitis produces scarring, leaflet thickening, commissural fusion, and eventually rheumatic heart disease (RHD), most often involving the mitral valve and then the aortic valve. That mechanism explains two findings that can otherwise seem contradictory. The joints may be intensely painful but heal without erosions or permanent damage, while a patient with mild early cardiac findings may accumulate lasting valve injury. Preventing recurrent attacks, rather than simply relieving the first episode, determines much of the long-term cardiac outcome. GAS...