Symptoms vary greatly. Often the damage to heart valves isn't immediately noticeable. A damaged heart valve either doesn't fully close or doesn't fully open.
Typically, symptoms of rheumatic fever appear about two weeks after the onset of an untreated strep throat infection. Apart from the sore throat caused by the strep infection, children have a fever and feel ill. Commonly, the child will have a very painful, swollen and red joint -- usually a large joint like a knee, ankle, elbow or shoulder -- that goes away after a day or two only to be replaced by the same findings in another joint. Short-lived skin rashes may occur, but are not common. Even if the heart is affected, it is usually not sever enough to cause symptoms, and occasionally the child may be short of breath.
Most cases of strep throat, including untreated infections, do not cause rheumatic fever. However, if rheumatic fever affects the heart valves, it can disrupt normal blood flow through the heart and cause damage to the heart.
Eventually, damaged heart valves can cause serious, even disabling, problems. These problems depend on how bad the damage is and which heart valve is affected. The most advanced condition is congestive heart failure. This is a heart disease in which the heart enlarges and can't pump out all its blood.
