Rheumatic Fever

Definition, Etiology, PathogenesisTop

Acute rheumatic fever (ARF) is an autoimmune disease caused by an excessive immune response to group A beta-hemolytic streptococcus (GABHS) infection, which occurs in ~3% of patients with untreated streptococcal pharyngitis and tonsillitis. The immune response is directed against epitopes similar to proteins found in the myocardium, heart valves, synovia, skin, hypothalamus, and caudate nucleus. The disease is rare in resource-rich countries, but the incidence is higher in low- and middle-income countries, in particular in Africa, and in some Indigenous populations, such as those in Australia and New Zealand. It is usually diagnosed in children aged between 5 and 15 years.

Clinical Features and Natural HistoryTop

1. Signs and symptoms of streptococcal pharyngitis (see Pharyngitis (Tonsillitis)).

2. Signs and symptoms of rheumatic fever usually develop 2 to 3 weeks after pharyngitis:

1) Polyarthritis affecting large joints (35%-66% of patients) is always asymmetric and accompanied by characteristic swelling, severe pain, tenderness, and erythema. Untreated arthritis persists for 2 to 3 weeks and does not lead to permanent joint damage.

2) Carditis (50%-70% of patients) may involve the endocardium, myocardium, and pericardium, but valvulitis is the most common feature. Although murmurs of aortic or mitral regurgitation may be heard, diagnosis by echocardiography in the absence of auscultatory findings is increasingly being recognized.

3) Sydenham chorea (10%-30% of patients) manifests as involuntary movements of the trunk or extremities. It is associated with muscle weakness and emotional lability.

4) Erythema marginatum (<6% of patients) is a pink rash that develops on the trunk and proximal parts of extremities.

5) Painless subcutaneous nodules (0%-10% of patients) on the extensor surfaces of elbows and knees are usually seen in patients with heart involvement.

3. Natural history: In patients without cardiac involvement, the disease has a mild course. The majority of relapses occur within 2 years of the first episode. Each recurrence of rheumatic fever increases the risk of mitral or aortic valve disease.

DiagnosisTop

Diagnostic Tests

1. Laboratory tests:

1) A positive throat swab or rapid antigen test for acute GABHS infection (see Pharyngitis (Tonsillitis)).

2) Elevations in the erythrocyte sedimentation rate (ESR) and serum C-reactive protein (CRP) levels, which persist for up to several months.

3) Increasing antistreptolysin O (ASO) or other streptococcal antibodies (anti-deoxyribonuclease B [anti-DNase B]).

2. Echocardiography to detect evidence of valvular dysfunction, most commonly mitral or aortic regurgitation (valvular stenosis is usually a late sequela).

Diagnostic Criteria

1. Jones criteria:

1) Major manifestations: Carditis, polyarthritis, chorea, erythema marginatum, subcutaneous nodules.

2) Minor manifestations: Polyarthralgia, fever, elevated ESR or serum CRP levels, a prolonged PR interval.

2. The first episode of rheumatic fever is diagnosed in patients with a documented prior GABHS infection (most frequently diagnosed on the basis of elevated ASO titers) and ≥2 positive major Jones criteria or 1 major + 2 minor Jones criteria.

TreatmentTop

1. Patients with suspected ARF are typically admitted to hospital for evaluation.

2. Start anti-inflammatory agents for arthritis. Acetylsalicylic acid (ASA) has been typically used. A glucocorticoid can be added in patients who cannot tolerate nonsteroidal anti-inflammatory drugs.

3. Treat for acute streptococcal pharyngitis with antibiotics to eradicate bacteria from the oropharynx. The risk of heart involvement is almost completely eliminated if the antibiotics are started within 10 days from the onset of the symptoms of pharyngitis.

PreventionTop

1. Primary prevention: Effective treatment of streptococcal pharyngitis.

2. Secondary prevention: In patients with confirmed rheumatic fever, prevention of relapses should be the goal using continuous antimicrobial prophylaxis for up to 5 years or until the age of 21 for rheumatic fever without carditis, for up to 10 years or until 21 years of age for rheumatic fever with carditis but no residual heart disease, and for up to 10 years or until 40 years when there is carditis and residual heart disease. Intramuscular benzathine penicillin G (INN benzathine benzylpenicillin) is the antibiotic of choice. Secondary choices include oral penicillin V (INN phenoxymethylpenicillin); in patients with serious allergies to penicillin, a macrolide can be used (azithromycin or erythromycin). The dosing varies by age and region and usually requires consultation with an infectious disease specialist.