Rheumatic Fever Overview

Study Notes

Autoimmune complication following infection with Group A β-hemolytic streptococcus (GAS)
Typically occurs after untreated strep throat (pharyngitis or tonsillitis)
GAS skin infections (erysipelas, impetigo, cellulitis) are more likely to lead to poststreptococcal glomerulonephritis rather than rheumatic fever
Classified as a type II hypersensitivity reaction due to molecular mimicry
Antibodies against GAS M protein cross-react with myocardial and neuronal proteins, primarily myosins, causing an autoimmune inflammatory response in these tissues
Myocarditis is the leading cause of death in the acute phase of rheumatic fever

Requires evidence of recent streptococcal infection:
- 2 major criteria OR
- 1 major and 2 minor criteria
Evidence of recent streptococcal infection can be confirmed through:
- Antistreptolysin O titre (ASOT) > 200 IU/mL
- History of scarlet fever
- Positive throat swab
- Elevated DNase B titre

Major Criteria:
- Joints: Polyarthritis (migratory inflammation of large joints, often knees, ankles, elbows, wrists)
- Heart: Carditis (endocarditis, myocarditis, pericarditis)
- Nodules: Subcutaneous nodules (firm, pea-sized, non-tender, commonly found on extensor surfaces like knees, elbows, and over the spine)
- Erythema marginatum: Non-itchy rash with pink rings on the trunk and limbs
- Sydenham's chorea: Involuntary, rapid movements affecting the face, hands, and feet
Minor Criteria:
- Elevated inflammatory markers (ESR or CRP)
- Fever
- Arthralgia (if arthritis is not a major criterion)
- Prolonged PR interval on ECG

Aschoff bodies: Characteristic foci of chronic inflammation in the myocardium during acute rheumatic fever
Anitschkow cells: Reactive histiocytes with distinctive wavy nuclei within Aschoff bodies, indicating acute rheumatic myocarditis

Bed Rest: Recommended until CRP levels normalize for two consecutive weeks (up to 3 months in some cases)
Antibiotic Therapy:
- Benzylpenicillin: 0.6-1.2 g IV initially, followed by phenoxymethylpenicillin 250-500 mg PO four times daily for 10 days
- Penicillin-allergic patients: Erythromycin or azithromycin for 10 days
Analgesia for Carditis/Arthritis:
- Aspirin: 100 mg/kg/day PO divided doses (max 4-8 g/day) initially, then 70 mg/kg/day for 6 weeks - Monitor salicylate levels (toxicity can lead to tinnitus, hyperventilation, metabolic acidosis)
- Prednisolone: Added for moderate-to-severe carditis (cardiomegaly, congestive heart failure, third-degree heart block)
- Joint Immobilization: For severe arthritis to minimize discomfort
Chorea Management: Haloperidol (0.5 mg every 8 hours PO) or diazepam for symptomatic relief

Chronic Rheumatic Heart Disease: Up to 60% of patients with carditis develop chronic valvular heart disease, severity correlates with initial carditis severity
Acute rheumatic episodes typically last around 3 months - Recurrence risk is increased with subsequent streptococcal infections, pregnancy, or oral contraceptive use
Valve Involvement:
- Mitral valve (70%) - Most commonly affected
- Aortic valve (40%)
- Tricuspid (10%) and pulmonary valves (2%) - Less common
- Acute attacks can cause valvular regurgitation, stenosis develops over time

Penicillin: lifelong prophylaxis to prevent recurrences (recommended for patients with previous rheumatic fever):
- Benzathine penicillin G: 1.2 million units IM every 4 weeks
- Oral penicillin V 250 mg bid
Sulfadiazine: Alternative if penicillin allergy is present
Prophylaxis: Continue until 21 years old or 10 years after last attack (whichever is later