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acute rheumatic fever

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"rheumatic fever"[MeSH Terms] AND diagnosis

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Acute Rheumatic Fever (ARF)

Definition and Background

Acute rheumatic fever is a systemic inflammatory disease that follows pharyngeal infection with Group A beta-hemolytic Streptococcus (GABHS, S. pyogenes). It affects the connective tissue of the heart, joints, CNS, and skin through an immune-mediated mechanism. It is a leading cause of acquired heart disease in developing countries.

Epidemiology

  • Primarily affects children aged 5-15 years (rare before age 3, infrequent after 15; most cases age 4-9)
  • Peaks more severely in younger children (greater fever, carditis); adults show more arthritis
  • Occurs equally in men and women, but rheumatic heart disease is more common in women
  • Incidence has fallen in developed countries over 50 years, but sporadic outbreaks still occur in North America
  • Remains highly prevalent in developing regions (Sub-Saharan Africa, South Asia, Pacific Islands)
  • Goldman-Cecil Medicine, p. 3042-3043

Pathobiology - Molecular Mimicry

The pathobiology involves an immune mechanism triggered by molecular mimicry:
  • Similarities between streptococcal antigens and human proteins lead to cross-reactive antibodies and T cells that attack host tissue
  • Carditis: antibody binding + T-cell infiltration of the heart
  • Arthritis: immune complex deposition in joints (synovial fluid is sterile with lymphocyte predominance)
  • Chorea: antibody binding to basal ganglia
  • Skin manifestations: delayed hypersensitivity reactions
Only rheumatogenic strains of GABHS cause ARF (mucoid types 3, 5, 18). Notably, the nephritogenic and rheumatogenic strains are different, so poststreptococcal GN and ARF rarely co-occur.
  • Goldman-Cecil Medicine, p. 3043; Tintinalli's Emergency Medicine, p. 966

Clinical Manifestations

ARF develops approximately 2-3 weeks after streptococcal pharyngitis (average 18.6 days). Chorea has a longer latency - usually 4-8 weeks. Symptoms persist 2-4 weeks.
ManifestationFrequency
Fever>90%
Arthritis (large joint polyarthritis)60-75%
Carditis (pancarditis)>50%
Sydenham chorea~30%
Subcutaneous nodules<10%
Erythema marginatum<10%

1. Arthritis

  • Most common and often earliest major symptom
  • Classically migratory polyarthritis of large joints; additive pattern also seen (especially adults)
  • Knees (76%), ankles (50%), elbows/wrists (12-15%) most involved
  • Tenderness often disproportionate to physical findings
  • Untreated patients typically have 6-16 affected joints
  • Responds dramatically to NSAIDs - failure to respond should prompt reconsideration of diagnosis

2. Carditis - Pancarditis

  • All layers of the heart may be involved
  • Most significant = valvulitis: mitral valve nearly always involved; aortic valve in 20-30%
  • Initially presents as valvular regurgitation
  • New or changing murmurs, cardiomegaly, congestive heart failure, pericarditis are key features
  • Subclinical (echocardiographic) valvulitis is recognized in the 2015 AHA Jones Criteria revision

3. Sydenham Chorea (St. Vitus Dance)

  • Involuntary, non-rhythmic, purposeless movements of body, limbs, and face
  • Usually more pronounced on one side
  • Stops during sleep (distinguishing feature)
  • Resolves within weeks to months, usually without treatment

4. Erythema Marginatum

  • Pink, non-pruritic, blanching macules/papules
  • Spread in a serpiginous (snake-like) pattern on trunk and proximal limbs (not face)

5. Subcutaneous Nodules

  • 0.5-2 cm, painless, firm
  • Found over bony prominences or extensor tendons
  • Almost always associated with significant carditis

Diagnosis - Revised Jones Criteria (2015 AHA)

No single definitive test exists. Diagnosis requires fulfilling the Jones criteria plus evidence of antecedent GAS infection.
The 2015 revision stratifies by population risk:
Low-risk population: ARF incidence <2 per 100,000 school-aged children/year OR RHD prevalence ≤1 per 1000/year

For initial ARF: 2 major OR 1 major + 2 minor criteria

Low-Risk PopulationsModerate/High-Risk Populations
MajorCarditis (clinical or subclinical echo), Polyarthritis, Chorea, Erythema marginatum, Subcutaneous nodulesSame + Monoarthritis also counts
MinorPolyarthralgia, Fever ≥38.5°C, ESR ≥60 mm/h and/or CRP ≥3.0 mg/dL, Prolonged PR intervalMonoarthralgia, Fever ≥38.5°C, ESR ≥30 mm/h and/or CRP ≥3.0 mg/dL, Prolonged PR interval
For recurrent ARF: 2 major, or 1 major + 2 minor, or 3 minor criteria

Evidence of antecedent GAS infection:

  • Positive throat culture for GAS
  • Positive rapid strep antigen test
  • Rising/elevated ASO (antistreptolysin O) or anti-DNase B titers
  • History of scarlet fever

Laboratory findings:

  • Elevated ESR and CRP
  • Normochromic, normocytic anemia
  • Leukocytosis
  • Prolonged PR interval on ECG
  • Echocardiogram: recommended to confirm and assess valvular involvement
  • Goldman-Cecil Medicine, p. 3043-3044; Tintinalli's Emergency Medicine, p. 966

Treatment

1. Eradication of GAS (Primary Treatment)

Treat all patients even if throat culture is negative at presentation - do not delay for culture results. Family/household contacts should also be tested and treated if positive.
Without penicillin allergy:
DrugDoseDuration
Benzathine penicillin G IM<27 kg: 600,000 U; ≥27 kg: 1,200,000 USingle dose
Penicillin V oralChildren: 250 mg 2-3x/day; Adults: 500 mg twice daily10 days
Amoxicillin oral50 mg/kg once daily (max 1000 mg)10 days
With penicillin allergy: Cephalexin, cefadroxil, clindamycin, azithromycin, or clarithromycin x 10 days (azithromycin x 5 days)

2. Anti-inflammatory Treatment

Arthritis, fever, and rash:
  • NSAIDs - first-line; symptoms typically respond promptly
  • Aspirin: 80-100 mg/kg/day in divided doses (max 4-8 g/day)
  • Naproxen: 10-20 mg/kg/day divided twice daily (alternate option)
  • Continue treatment 1-2 weeks until all ARF symptoms resolve (not just joints)
Carditis:
  • Treat associated heart failure: diuretics, ACE inhibitors/ARBs, fluid restriction, bed rest
  • Corticosteroids: considered in severe carditis by some experts (high-quality evidence lacking)
  • Valve surgery: rarely needed acutely; may be helpful for acute valve leaflet rupture
Chorea:
  • Usually resolves without treatment
  • Carbamazepine or valproic acid for severe cases
  • Rheumatology 2-Volume Set 2022, p. 3481-3510; Goldman-Cecil Medicine, p. 3044

Secondary Prophylaxis

This is the cornerstone of preventing recurrent ARF and progressive valve damage.
Drug of choice: Intramuscular benzathine penicillin G 1.2 million units every 4 weeks (every 3 weeks in high-risk patients, as levels drop in the 4th week)
Alternative: Oral penicillin V 250 mg twice daily; oral macrolide (azithromycin 250 mg daily) for penicillin-allergic

Duration of prophylaxis:

CategoryDuration
ARF without carditis5 years or until age 21 (whichever is longer)
ARF with carditis, no residual valve disease10 years or until age 21 (whichever is longer)
ARF with persistent valve disease (RHD)Minimum 10 years; often lifelong
  • Compliance is critical: 0.45% recurrence in compliant vs. 11.5% in non-compliant patients (prospective international study, n=1790)
  • High-risk individualization based on: age, presence of RHD, crowding, number of prior attacks, occupation
A 2024 Cochrane systematic review on secondary prophylaxis (PMID 39312290) confirmed the role of long-term antibiotic prophylaxis in preventing ARF recurrence and progression to rheumatic heart disease.

Complications - Rheumatic Heart Disease (RHD)

  • 35-70% of patients with ARF develop chronic rheumatic heart disease despite acute treatment
  • 35-72% develop carditis; an additional 18% have subclinical echocardiographic carditis
  • Valves affected (nearly always): Mitral valve (~100%), Aortic valve (20-30%), Tricuspid (histologic involvement 15-40%, rarely clinically relevant), Pulmonary (rare)
  • Most common lesion: mitral regurgitation (acute); mitral stenosis develops from progressive scarring - most common cause of mitral stenosis worldwide
  • RHD severity peaks in the 3rd-4th decade of life
  • Leading cause of bacterial endocarditis and cardiovascular morbidity/mortality in developing countries
Echocardiographic screening in endemic regions can detect latent RHD and guide secondary prophylaxis.
  • Goldman-Cecil Medicine, p. 3044

Key High-Yield Points Summary

  1. Cause: Group A Strep pharyngitis only (not skin infections) triggers ARF
  2. Mechanism: Molecular mimicry - cross-reactive immune response
  3. Diagnosis: Revised Jones Criteria (2015 AHA) - requires GAS evidence
  4. Most common manifestation: Arthritis (migratory polyarthritis)
  5. Most serious manifestation: Carditis (mitral valve most affected)
  6. Chorea hallmark: Stops during sleep
  7. Treatment: Penicillin + NSAIDs; steroids for severe carditis
  8. Prevention: Long-term benzathine penicillin G every 4 weeks
  9. Sequela: Mitral stenosis (most common cause worldwide)
  10. Subclinical carditis (echo only) now recognized in Jones Criteria since 2015
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