Acute Rheumatic Fever (ARF)

A 12 year old boy presents with fever and severe migratory joint pain involving the knees and ankles for 5 days. His mother reports a sore throat approximately 3 weeks earlier that was not treated with antibiotics. On examination, temperature is 38.7°C, pulse is 112/min, and a new holosystolic murmur is heard at the apex. Both knees are swollen and tender, with symptoms shifting from one joint to another. Laboratory investigations reveal elevated ESR and CRP, prolonged PR interval on ECG, and elevated antistreptolysin O (ASO) titers. Echocardiography demonstrates mitral regurgitation. Diagnosis?

Diagnosis is acute rheumatic fever (ARF).

1. Definition

Acute rheumatic fever is an immune-mediated inflammatory disease that occurs following group A β-hemolytic streptococcal pharyngitis.

It results from molecular mimicry and cross-reactive antibodies directed against host tissues.

2. Epidemiology

  1. Most commonly affects children 5–15 years of age
  2. Leading cause of rheumatic heart disease worldwide
  3. High recurrence risk with untreated streptococcal reinfection
  4. More common in overcrowded and resource-limited settings

3. Risk Factors

  1. Untreated or inadequately treated GAS pharyngitis
  2. Prior history of acute rheumatic fever
  3. Overcrowding
  4. Low socioeconomic status
  5. Genetic susceptibility

4. Pathophysiology

  1. Streptococcal antigens trigger immune activation
  2. Cross-reactive antibodies attack host tissues
  3. Inflammation affects:
    • Heart
    • Joints
    • Central nervous system
    • Skin
  4. Recurrent inflammation may lead to chronic valvular fibrosis and rheumatic heart disease

5. Clinical Features

5.1 Constitutional Features

  1. Fever
  2. Fatigue
  3. Malaise

5.2 Articular Manifestations

Migratory Polyarthritis

  1. Most common manifestation
  2. Usually involves large joints:
    • Knees
    • Ankles
    • Wrists
    • Elbows
  3. Intensely painful and migratory
  4. Sterile inflammatory arthritis
  5. Dramatic response to NSAIDs
  6. Self-limited without residual deformity

5.3 Cardiac Manifestations

Pancarditis

May involve:

  1. Endocardium
  2. Myocardium
  3. Pericardium

Common findings:

  1. Tachycardia
  2. Cardiomegaly
  3. New murmur
  4. Heart failure in severe disease

5.4 Valvular Involvement

  1. Mitral valve most commonly affected
  2. Acute mitral regurgitation is the most common early lesion
  3. Aortic valve involvement may occur
  4. Chronic disease may lead to valvular fibrosis and stenosis

5.5 Neurologic Manifestation

Sydenham Chorea

  1. Involuntary purposeless movements
  2. Emotional lability
  3. Hypotonia
  4. “Milkmaid grip”
  5. Chorea may occur months after streptococcal infection
  6. May present after inflammatory markers have normalized

5.6 Dermatologic Manifestations

Erythema Marginatum

  1. Serpiginous nonpruritic rash
  2. Usually involves trunk and proximal limbs

Subcutaneous Nodules

  1. Firm painless nodules over extensor surfaces
  2. Associated with severe carditis

6. Jones Criteria

6.1 Major Criteria

  1. Carditis (clinical or subclinical on echocardiography)
  2. Migratory polyarthritis
  3. Sydenham chorea
  4. Erythema marginatum
  5. Subcutaneous nodules

High-Risk Population Modification

In high-risk populations:

  1. Monoarthritis may qualify as a major criterion
  2. Polyarthralgia may qualify as a major criterion

6.2 Minor Criteria

  1. Fever
  2. Arthralgia
  3. Elevated ESR or CRP
  4. Prolonged PR interval on ECG

Lower fever and inflammatory marker thresholds are used in high-risk populations

6.3 Diagnostic Requirement

Diagnosis requires:

  1. Two major criteria

OR

  1. One major plus two minor criteria

PLUS

  1. Evidence of recent GAS infection

6.4 Diagnostic Exceptions

  1. Sydenham chorea alone may establish diagnosis
  2. Indolent carditis may also support diagnosis with evidence of prior GAS infection

7. Evidence of Recent Streptococcal Infection

  1. Elevated ASO titers
  2. Elevated anti-DNase B titers
  3. Positive throat culture
  4. Positive rapid antigen detection test (RADT)
  5. Positive nucleic acid amplification test (NAAT)

Throat culture may already be negative by the time ARF develops

8. Investigations

  1. CBC
  2. ESR and CRP
  3. ECG showing prolonged PR interval
  4. Chest X-ray showing cardiomegaly
  5. Echocardiography for detection of carditis and valvular disease

Echocardiography is essential because it can detect subclinical carditis

9. Management

9.1 Eradication of GAS

Penicillin Therapy

  1. Penicillin V for 10 days

OR

  1. Single intramuscular dose of benzathine penicillin G

This eradicates streptococcal infection but does not directly treat inflammatory manifestations

9.2 Alternative Antibiotics

  1. Cephalosporins
  2. Macrolides in true penicillin allergy

9.3 Arthritis Treatment

  1. NSAIDs are first-line therapy
  2. Aspirin traditionally used
  3. Naproxen commonly preferred
  4. Rapid dramatic response is characteristic

Lack of response suggests an alternative diagnosis

9.4 Carditis Management

  1. Supportive care
  2. Management of heart failure if present
  3. Corticosteroids may be used in severe carditis

No anti-inflammatory therapy has clearly been shown to prevent long-term rheumatic valvular disease

9.5 Heart Failure Management

  1. Diuretics
  2. ACE inhibitors
  3. Salt and fluid restriction

9.6 Chorea Management

  1. Usually self-limited
  2. Severe chorea may require:
    • Valproate
    • Carbamazepine
    • Haloperidol
  3. Steroids or IVIG may be considered in severe cases

10. Secondary Prevention

Benzathine Penicillin G

  1. Intramuscular injection every 4 weeks
  2. Every 3 weeks may be required in high-risk populations

Duration of Prophylaxis

No Carditis

  • 5 years or until age 21 years

Carditis Without Residual Valvular Disease

  • 10 years or until age 21 years

Residual Valvular Disease

  • 10 years or until age 40 years
  • Lifelong prophylaxis may be required in severe disease

11. Complications

  1. Rheumatic heart disease
  2. Chronic valvular fibrosis
  3. Mitral stenosis
  4. Heart failure
  5. Recurrent acute rheumatic fever

12. Prognosis

  1. Most joint manifestations resolve completely
  2. Carditis determines long-term prognosis
  3. Recurrent episodes significantly increase risk of rheumatic heart disease

13. Key Clinical Insight

Child with fever, migratory polyarthritis, and recent untreated streptococcal pharyngitis should be evaluated immediately for acute rheumatic fever using the Jones criteria

14. Key Exam Points

  1. ARF is a type II hypersensitivity reaction following GAS pharyngitis
  2. Most important risk factor is untreated streptococcal pharyngitis
  3. Mitral valve is most commonly affected
  4. Acute mitral regurgitation is the most common early lesion
  5. Migratory large-joint arthritis shows dramatic NSAID response
  6. Echocardiography can detect subclinical carditis
  7. Sydenham chorea may occur months after infection
  8. Recurrent episodes lead to rheumatic heart disease
  9. Secondary prophylaxis is essential to prevent recurrence
  10. Diagnosis is clinical and based on Jones criteria with evidence of recent GAS infection
By Prabin Duwadee at

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