Which infection most often precedes rheumatic carditis?

• A. Group A streptococcal throat infection
• B. Staphylococcal skin infection
• C. Viral URI
• D. Pneumococcal pneumonia

Answer: (C)

Rheumatic carditis arises as an immune-mediated reaction after a Group A Streptococcus pharyngitis. The streptococcal M protein shares similar features with heart tissue, so antibodies made to fight the infection can cross-react with the heart, causing inflammation of the heart layers. This is why the classic precursor is a throat infection with Group A beta-hemolytic Streptococcus. Skin infections from the same organism can lead to different post-streptococcal issues, like glomerulonephritis, but they are not the typical trigger for rheumatic fever. Viral upper respiratory infections do not usually set off rheumatic carditis. So the infection most likely to precede rheumatic carditis is a Group A Streptococcus throat infection, occurring often a couple of weeks after the illness.