This disorder occurs secondary to an infection by Group A beta-hemolytic streptococci particularly M serotypes 1, 3, 5, 6, 14, 18, 19, and 24. This disease may manifest with symptoms of joint, heart, cutaneous, central nervous system, and subcutaneous tissue involvement. The most diagnostically useful symptoms are polyarthritis, carditis, subcutaneous nodules, Sydenham's chorea, and erythema marginatum.
The incidence of rheumatic fever developing after streptococcal pharyngitis is between 0.5 to 3%. Pyoderma or other streptococcal infections are not associated with the development of rheumatic fever. Prompt therapy for streptococcal pharyngitis does prevent the development of rheumatic fever.
A migratory polyarthritis affecting the large joints (knees, ankles, elbows, and shoulders) is the most frequent initial symptom and occurs in 85 to 95% of cases. The arthritis usually resolves in one joint as it moves to another; however, the arthritis may be persistent and involve multiple joints at once. The arthritic symptoms are transient, lasting from 2 to 4 weeks and are very sensitive to salicylates. Patients afflicted with several repeat acute episodes may develop Jaccoud's arthropathy.
Cardiac involvement is considered an ominous finding and is described in 30 to 90% of cases. Symptoms include valvular damage (most notably mitral stenosis although other valve lesions such as mitral regurgitation and aortic insufficiency may be involved), tachycardia which is disproportionate to the level of fever and persists during sleeping, congestive heart failure, cardiomegaly, pericarditis, and conduction disturbances. Electrocardiographic changes include prolongation of the P-R interval and extrasystoles; however, these changes are so frequent, that they are not considered consistent with carditis unless there is associated cardiomegaly or murmurs present.
The development of Sydenham's chorea occurs late in the disease course often weeks or months after the initial streptococcal infection. The onset is gradual and manifests initially as emotional liability. This is followed by the development of abrupt, short, nonrhythmic involuntary movements, incoordination, weakness, and grimacing. Other neurologic symptoms include difficulty maintaining posture and a propensity to pronate the hands. Findings may be unilateral or bilateral and tend to disappear while the patient is sleeping.
When subcutaneous nodules are a symptom of disease, they tend to be located on the extensor surfaces of the elbows and forearms. The nodules may persist for approximately 4 weeks.
The characteristic rash of rheumatic fever is termed erythema marginatum. It is a nonpruritic rash which spares the face and involves the trunk and extremities. The rash is characterized by its reddish pink rim which extends outward leaving behind a blanching interior. The rash usually appears when the disease is acute.
Associated lab abnormalities include elevated ESR and CRP. Often tests used to indicate either current or previous infection (throat cultures or antistreptolysin O, antihyaluronidase and anti-DNAase B titers, respectively) are positive. The differential diagnosis is extensive and includes other causes of polyarthritis. The diagnosis is established clinically based on the presence of the Jones criteria.
Therapy is directed at the underlying streptococcal infection. Benzathine penicillin G administered intramuscularly in a single dose (600,000 units in children and 1,200,000 units in adults) or oral phenoxymethyl penicillin (250,000 units QID for 10 days) are most effective. Erythromycin is an acceptable alternative in penicillin allergic patients. Symptomatic therapy for arthritis entails salicylates. Once the acute phase has subsided, secondary prophylaxis with monthly penicillin therapy (Benzathine penicillin G 1,200,000 units IM) should be administered. Since the incidence of recurrence is highest during the 5 years immediately following the initial acute episode, prophylaxis should continue for at least this length of time or until patients reach 18 years of age.