What are the diagnostic criteria and treatment options for rheumatic fever?

Diagnosis and Management of Rheumatic Fever

The diagnosis of acute rheumatic fever requires application of the 2015 revised Jones criteria, which includes subclinical carditis detected by echocardiography as a major criterion, with different diagnostic standards for low-risk versus moderate/high-risk populations. 1

Diagnostic Criteria

Evidence of Preceding Group A Streptococcal (GAS) Infection

• Positive throat culture for GAS
• Elevated or rising anti-streptolysin O (ASO) titer
• Positive rapid GAS antigen test

Jones Criteria Requirements

Initial diagnosis requires:

• 2 major criteria OR
• 1 major criterion + 2 minor criteria
• PLUS evidence of preceding GAS infection 1

Major Criteria

1. Carditis (clinical or subclinical detected by echocardiography)
2. Arthritis
   • Low-risk populations: Polyarthritis only
   • Moderate/high-risk populations: Monoarthritis or polyarthritis 1
3. Chorea (Sydenham's)
4. Erythema marginatum
5. Subcutaneous nodules

Minor Criteria

• Fever
  • Low-risk populations: ≥38.5°C
  • Moderate/high-risk populations: ≥38°C 1
• Arthralgia
  • Low-risk populations: Polyarthralgia only
  • Moderate/high-risk populations: Monoarthralgia or polyarthralgia 1
• Elevated acute phase reactants
  • ESR: ≥60 mm/h for low-risk, ≥30 mm/h for moderate/high-risk
  • CRP: ≥3.0 mg/dL 1
• Prolonged PR interval on ECG (accounting for age)

Echocardiographic Assessment for Carditis

Doppler echocardiography is essential for detecting clinical or subclinical carditis with these key features differentiating pathological from physiological regurgitation:

• Mitral regurgitation (most common finding):

  • Jet length ≥2 cm
  • Velocity >3.0 m/s
  • Holosystolic pattern 1

• Aortic regurgitation:

  • Jet length ≥1 cm
  • Velocity >3.0 m/s
  • Holodiastolic pattern 1

Treatment Approach

Eradication of GAS Infection

• First-line: Penicillin V orally for 10 days OR benzathine penicillin G as a single intramuscular injection
• For penicillin-allergic patients: Oral macrolide or azalide 1

Anti-inflammatory Therapy

• For arthritis: NSAIDs (aspirin 80-100 mg/kg/day divided into 4 doses)
• For carditis:
  • Mild to moderate: NSAIDs
  • Severe: Prednisone 1-2 mg/kg/day (maximum 60 mg/day) for 2-3 weeks, followed by gradual tapering over 2-3 weeks 1

Secondary Prophylaxis

• Benzathine penicillin G: 1.2 million units IM every 3-4 weeks
• Duration:
  • No carditis: Minimum 5 years or until 21 years of age
  • Carditis without residual heart disease: 10 years or until 21 years of age
  • Carditis with residual heart disease: 10 years or until 40 years of age; sometimes lifelong 1

Special Considerations

"Possible" Rheumatic Fever

For cases where criteria are not fully met but clinical suspicion is high:

• Consider 12 months of secondary prophylaxis followed by reevaluation 1

Recurrent Attacks

• Diagnosis may be made with less stringent criteria
• Lower threshold for diagnosis in patients with previous history of rheumatic fever 2

Monitoring and Follow-up

• Serial ESR and CRP measurements to track inflammation
• Repeat echocardiography to assess valvular changes
• Regular clinical follow-up 1

Common Pitfalls to Avoid

• Misinterpreting elevated ASO titers without clinical correlation
• Failing to use echocardiography to detect subclinical carditis
• Inadequate prophylaxis regimens
• Confusing rheumatic fever with other conditions like Lyme disease, serum sickness, drug reactions, and post-streptococcal reactive arthritis 1

The 2015 revision of the Jones criteria represents a significant update from previous versions by including echocardiographic findings and recognizing population-specific differences in disease presentation, which helps improve diagnostic accuracy and reduce both under- and over-diagnosis of this potentially devastating condition 2, 3.