Rheumatic fever can affect the heart, joints, skin and other organs. Children between the ages of 5 and 15 are most susceptible to this condition. Rheumatic fever is caused when the body's immune system makes antibodies to fight the strep bacteria that cause an infection. Certain parts of the bacteria are similar to some kinds of human tissues. These antibodies become confused and begin to target tissues in the body.
Rheumatic fever is rare.
Most sore throats are not strep infections. Of those that are, only about three in one thousand people who have had strep develop rheumatic fever. The most serious complication of the disorder is when the heart is affected. The symptoms of rheumatic fever can appear up to six weeks after a strep infection. Usually the condition is treated with antibiotics like penicillin or erythromycin.