Acute Rheumatic Fever is an immune-mediated, multisystem inflammatory disease occurring several weeks after an untreated Group A beta-hemolytic Streptococcus (GAS) pharyngitis (sore throat), primarily affecting children aged 3 to 15 years. It is a major cause of acquired heart disease in children worldwide.
Pathophysiology
- ARF is a post-infectious autoimmune response triggered by molecular mimicry.
- Antibodies produced against the M protein of GAS cross-react with host tissues such as the heart, joints, brain, and skin.
- This cross-reactivity results in inflammation and tissue damage.
- Only a small percentage of untreated GAS pharyngitis cases develop ARF, but the risk of recurrence increases significantly with subsequent untreated infections.
- The GAS bacteria produce enzymes and toxins (notably streptolysin O ), with anti-streptolysin O (ASO) antibody titers serving as a diagnostic marker.
Clinical Features
Diagnostic Criteria: Modified Jones Criteria
- Diagnosis requires either:
- 2 major criteria + 1 minor criterion , or
- 1 major criterion + 2 minor criteria ,
alongside evidence of preceding GAS infection.
Major Criteria
- Migratory polyarthritis (large joints)
- Carditis (manifested by signs such as heart failure, tachycardia, pericardial rub, or murmurs)
- Sydenham’s chorea (involuntary movements)
- Erythema marginatum (non-pruritic, serpiginous rash)
- Subcutaneous nodules
Minor Criteria
- Fever
- Arthralgia (joint pain without inflammation)
- Elevated acute phase reactants (ESR, CRP, leukocytosis)
- Prolonged PR interval on ECG
- History of previous rheumatic fever
Investigations
- Anti-streptolysin O titer (ASOT): Elevated (commonly ≥ 1:300)
- Throat culture: Positive for Group A beta-hemolytic Streptococcus
- Erythrocyte Sedimentation Rate (ESR): Raised
- Chest X-ray: May show cardiomegaly if carditis is present
- Electrocardiogram (ECG): To detect conduction abnormalities (e.g., prolonged PR interval)
- Echocardiography: Assess valvular involvement and cardiac function
Management
Eradication of Streptococcal Infection
- Amoxicillin: 250–500 mg (children 25–50 mg/kg/day in divided doses) orally, TDS for 10 days
- Erythromycin: 12.5 mg/kg QDS for 10 days (for penicillin-allergic patients)
Control of Inflammation and Symptoms
- Aspirin: 75–100 mg/kg/day divided into 4–6 doses, gradually tapered over 2 weeks after symptom resolution
- Chorea management: Haloperidol 0.025 mg/kg TDS if chorea is present
- Bed rest until symptom resolution is recommended
Prevention
Primary Prevention
- Early diagnosis and adequate antibiotic treatment of GAS pharyngitis with:
- Benzathine penicillin G: 1.2 million units IM single dose
- OR Phenoxymethyl penicillin: 125–250 mg orally TDS for 10 days
- Avoid overcrowding to reduce transmission
Secondary Prevention (Prophylaxis)
- To prevent recurrence and progression to rheumatic heart disease:
- Without carditis: Benzathine penicillin 1.2 million units IM monthly for 5 years or until age 18, whichever is longer.
- With carditis: Lifelong monthly benzathine penicillin or erythromycin for penicillin-allergic patients.
Patient Education
- Importance of adherence to prophylactic antibiotics and regular follow-up
- Educate about the risk of rheumatic heart disease as a serious complication
- Emphasize early treatment of sore throats to prevent ARF
