What are the diagnostic criteria for rheumatic fever in a child or young adult with a recent streptococcal infection?

Diagnosis of Rheumatic Fever

Diagnose acute rheumatic fever using the revised Jones Criteria, which requires evidence of preceding group A streptococcal infection PLUS either 2 major manifestations OR 1 major and 2 minor manifestations, with different thresholds for low-risk versus moderate-to-high-risk populations. 1

Essential First Step: Document Streptococcal Infection

Before applying the Jones Criteria, you must demonstrate evidence of recent group A streptococcal (GAS) infection through one of these methods: 1

• Positive throat culture or rapid antigen detection test (RADT) - though these are often negative by the time rheumatic fever develops 1
• Elevated or rising anti-streptolysin O (ASO) titer - begins rising ~1 week after infection, peaks at 3-6 weeks 2, 3
• Elevated anti-DNase B titer - begins rising 1-2 weeks after infection, peaks at 6-8 weeks 2, 3
• Combined ASO and anti-DNase B testing detects up to 98% of proven streptococcal cases 4

Critical caveat: At least one-third of rheumatic fever cases result from inapparent streptococcal infections, making documentation challenging. 1 Anti-streptococcal antibody titers reflect past infection only and cannot diagnose acute pharyngitis. 1, 2

Major Manifestations (Population-Specific)

The 2015 AHA revision stratifies criteria based on population risk: 1

Low-Risk Populations (e.g., United States, Western Europe):

• Carditis (clinical and/or subclinical by echocardiography)
• Polyarthritis only
• Chorea
• Erythema marginatum
• Subcutaneous nodules

Moderate-to-High-Risk Populations (e.g., developing countries, indigenous populations):

• Carditis (clinical and/or subclinical)
• Monoarthritis OR polyarthritis 1
• Polyarthralgia (after excluding other causes) 1
• Chorea
• Erythema marginatum
• Subcutaneous nodules

Key distinction: Monoarthritis and polyarthralgia are accepted as major manifestations only in moderate-to-high-risk populations. 1

Minor Manifestations

Clinical:

• Fever (>38.5°C in low-risk; >37.5°C in moderate-to-high-risk populations) 1
• Polyarthralgia (low-risk populations only; cannot use if polyarthralgia counted as major) 1
• Monoarthralgia (moderate-to-high-risk populations only) 1

Laboratory:

• Elevated acute phase reactants:
  • ESR ≥60 mm/hr (low-risk) or ≥30 mm/hr (moderate-to-high-risk) 1
  • CRP ≥3.0 mg/dL (low-risk) or ≥3.0 mg/dL (moderate-to-high-risk) 1
  • Use peak ESR values as they evolve during disease course 1
• Prolonged PR interval on ECG (age-adjusted) 1, 5

Critical rule: Joint manifestations can only be counted in either the major OR minor category, never both in the same patient. 1

Diagnostic Algorithm

1. Confirm recent GAS infection (throat culture/RADT or elevated ASO/anti-DNase B) 1

2. Assess population risk (determines which manifestations qualify as major) 1

3. Apply Jones Criteria:

   • 2 major manifestations, OR
   • 1 major + 2 minor manifestations 1, 5

4. Exclude alternative diagnoses: Lyme disease, serum sickness, drug reactions, post-streptococcal reactive arthritis, infective endocarditis, congenital valve abnormalities 1, 6

Role of Echocardiography

Subclinical carditis detected by Doppler echocardiography is now accepted as a major manifestation, representing a major change from 1992 criteria. 1, 7 This is critical because:

• Clinical detection of soft murmurs is difficult with tachycardia 8
• Doppler/color flow mapping detects minor degrees of valvular regurgitation missed on auscultation 8
• Pathological mitral regurgitation in rheumatic fever shows specific features: jet length >2 cm, peak velocity >3.0 m/s, holosystolic jet 1

However, echocardiography findings must be interpreted carefully to distinguish rheumatic valvulitis from congenital abnormalities (bicuspid aortic valve, cleft mitral valve, mitral valve prolapse) and infective endocarditis. 1

Special Scenarios

Recurrent Rheumatic Fever:

In patients with documented prior rheumatic fever or rheumatic heart disease and confirmed GAS infection, 2 major OR 1 major + 2 minor OR 3 minor manifestations may suffice for diagnosis. 1 When only minor manifestations are present, exclude other causes before diagnosing recurrence. 1

"Possible" Rheumatic Fever:

When clinical presentation doesn't fulfill Jones Criteria but suspicion remains high (particularly in high-incidence settings), consider 12 months of secondary prophylaxis followed by reevaluation including repeat echocardiogram. 1

Exceptions to Jones Criteria:

• Chorea alone may be sufficient (often presents late when other manifestations have resolved) 5
• Indolent carditis discovered months after infection 5

Common Pitfalls to Avoid

• Do not use ASO/anti-DNase B to diagnose acute pharyngitis - these reflect past infection only and remain elevated for months 2, 3
• Do not diagnose rheumatic fever in children <3 years old unless exceptional circumstances exist, as it's extremely rare in this age group 1
• Do not count joint manifestations in both major and minor categories for the same patient 1
• Do not rely on echocardiography alone without clinical context - physiological regurgitation is common 1
• Remember age-specific normal values for ASO titers are higher in school-age children than adults 2, 4
• Distinguish chronic GAS carriers with viral pharyngitis from acute infection - carriers lack rising antibody titers 2