Carditis is frequently mild or asymptomatic and therefore difficult to detect. Although not fully understood, a person's immune system response to a streptococcal infection appears to cause tissue degeneration, most frequently heart valve tissue, and subsequently, cardiac disability or death. Polyarthritis is arthritis in a number of joints at a time. Chorea is a neurologic syndrome that may appear after a latent period of several months. Chorea is seen as rapid, purposeless, involuntary movements in the extremities and the face.
Subcutaneous nodules are firm, painless lesions that occur over bony surfaces just under the skin.
Erythema marginatum is a rash that appears mostly on the trunk and extremities. The peak age of incidence for rheumatic fever is 5 to 15 years, but cases do occur in adults. Acute rheumatic fever is rare in children less than 4 years of age. The average duration of an attack of acute rheumatic fever is 3 months or longer. Some people will have recurrent acute attacks of rheumatic fever, frequently causing more damage to the heart valves.