Rheumatic fever can occur after an infection of the throat with a bacterium called Streptococcus pyogenes, or group A streptococcus. Group A streptococcus infections of the throat cause strep throat or, less commonly, scarlet fever. Group A streptococcus infections of the skin or other parts of the body rarely trigger rheumatic fever.

The exact link between strep infection and rheumatic fever isn't clear, but it appears that the bacterium "plays tricks" on the immune system. The strep bacterium contains a protein similar to one found in certain tissues of the body. Therefore, immune system cells that would normally target the bacterium may treat the body's own tissues as if they were infectious agents — particularly tissues of the heart, joints, skin and central nervous system. This immune system reaction results in inflammation.

If your child receives prompt and complete treatment with an antibiotic to eliminate strep bacteria — in other words, taking all doses of the medication as prescribed — there's little to no chance of developing rheumatic fever. If your child has one or more episodes of strep throat or scarlet fever that aren't treated or not treated completely, he or she may — but won't necessarily — develop rheumatic fever.

Feb. 18, 2014