Acute Rheumatic Fever (ARF) – Paediatrics

1. Definition

Acute Rheumatic Fever (ARF) is an autoimmune inflammatory disease that occurs 2–3 weeks after infection with Group A β-hemolytic Streptococcus (GAS), usually following streptococcal pharyngitis.

It mainly affects children aged 5–15 years and can involve heart, joints, skin, and central nervous system.

The most serious complication is rheumatic heart disease (RHD) due to permanent valvular damage.

2. Etiology

The disease follows infection with:

• Group A β-hemolytic Streptococcus
• Species: Streptococcus pyogenes
• Infection site:

* Streptococcal pharyngitis (most common)

* Rarely skin infections

Not all strains cause ARF; rheumatogenic strains include M types 1, 3, 5, 6, 18, 24.

Risk factors:

• Age 5–15 years
• Crowded living conditions
• Poor socioeconomic status
• Recurrent untreated throat infections
• Genetic susceptibility

3. Pathophysiology

ARF results from molecular mimicry.

Mechanism

1. Streptococcal infection occurs in throat
2. Immune system produces antibodies against streptococcal M protein
3. These antibodies cross-react with human tissues, especially:

* Cardiac muscle

* Heart valves

* Synovium

* Brain basal ganglia

* Skin

Immune Reaction

Both immune responses occur:

1. Humoral immunity

• Antibodies against streptococcal antigens
• Cross-react with cardiac tissue

2. Cell-mediated immunity

• T-cell mediated inflammation

Characteristic lesion

Aschoff bodies

• Granulomatous inflammatory lesions found in heart tissue.

Resulting inflammation affects:

• Heart → Pancarditis
• Joints → Arthritis
• Brain → Sydenham chorea
• Skin → Rash and nodules

4. Pathology of Heart

ARF causes pancarditis (all layers of heart involved):

1. Endocarditis

• Inflammation of valves
• Small vegetations along valve edges
• Mainly affects:

* Mitral valve (most common)

* Aortic valve

2. Myocarditis

• Aschoff bodies in myocardium
• Causes cardiomegaly and heart failure

3. Pericarditis

• Fibrinous pericarditis
• Pericardial effusion possible

5. Clinical Features

Symptoms appear 2–3 weeks after streptococcal throat infection.

General symptoms

• Fever
• Malaise
• Loss of appetite
• Fatigue

6. Jones Criteria (Diagnosis)

Diagnosis uses Modified Jones Criteria.

Requires:

• 2 major criteria

OR

• 1 major + 2 minor criteria

AND

• Evidence of recent streptococcal infection

Major Criteria

1. Carditis

Occurs in 40–60% of patients.

Features:

• Tachycardia
• Cardiomegaly
• New heart murmur
• Mitral regurgitation murmur
• Aortic regurgitation murmur
• Pericardial friction rub
• Heart failure

Complication:

• Rheumatic heart disease

2. Migratory Polyarthritis

Most common manifestation.

Features:

• Large joints affected:

* Knees

* Ankles

* Elbows

* Wrists

• Migratory pattern
• Severe pain
• Redness and swelling
• Responds dramatically to aspirin

3. Sydenham Chorea (St. Vitus Dance)

Neurological disorder caused by basal ganglia involvement.

Features:

• Involuntary jerky movements
• Emotional lability
• Muscle weakness
• Poor handwriting
• Difficulty speaking
• "Milkmaid grip"
• "Pronator sign"

Occurs months after infection.

4. Erythema Marginatum

Rare skin manifestation.

Characteristics:

• Pink rash
• Non-itchy
• Ring-shaped lesions
• Clear center
• Appears on trunk and limbs
• Spares face

5. Subcutaneous Nodules

Rare but specific sign.

Features:

• Small painless nodules
• Located over:

* Elbows

* Knees

* Tendons

* Occiput

• Associated with severe carditis

Minor Criteria

Clinical

• Fever
• Arthralgia

Laboratory

• Elevated ESR
• Elevated CRP
• Prolonged PR interval on ECG

Evidence of Recent Streptococcal Infection

Required for diagnosis.

Tests include:

• Elevated ASO (Anti-streptolysin O) titer
• Elevated Anti-DNase B
• Positive throat culture
• Positive rapid streptococcal antigen test
• Recent scarlet fever

7. Investigations

Blood Tests

• ESR ↑
• CRP ↑
• Leukocytosis
• ASO titer ↑
• Anti-DNase B ↑

ECG

Findings:

• Prolonged PR interval
• Arrhythmias

Echocardiography

Important for detecting:

• Valvular regurgitation
• Carditis
• Ventricular function

Chest X-ray

• Cardiomegaly
• Pulmonary congestion

8. Differential Diagnosis

• Septic arthritis
• Juvenile idiopathic arthritis
• Infective endocarditis
• Systemic lupus erythematosus
• Kawasaki disease
• Viral myocarditis

9. Management

Treatment goals:

1. Eradicate streptococcal infection
2. Control inflammation
3. Manage carditis
4. Prevent recurrence

10. Eradication of Streptococci

First-line drug

Benzathine Penicillin G

Indication

Eradication of Group A streptococcus

Mechanism

Inhibits bacterial cell wall synthesis

Dose

• <27 kg: 600,000 units IM single dose
• ≥27 kg: 1.2 million units IM single dose

Alternative oral therapy

Penicillin V

Dose

• 250 mg orally 2–3 times daily for 10 days

Penicillin Allergy

Azithromycin

Mechanism

Macrolide antibiotic inhibiting protein synthesis

Dose

• 12 mg/kg once daily for 5 days

Adverse effects

• GI upset
• QT prolongation

11. Anti-Inflammatory Treatment

Aspirin

Indication

• Arthritis
• Mild carditis

Mechanism

• Inhibits prostaglandin synthesis (COX inhibitor)

Dose

• 80–100 mg/kg/day divided every 6 hours

Adverse effects

• Gastritis
• Tinnitus
• Reye syndrome (rare)

Monitoring

• Liver function
• Salicylate toxicity

Corticosteroids

Used in severe carditis or heart failure.

Drug

Prednisolone

Dose

• 1–2 mg/kg/day

Duration

• 2–3 weeks followed by taper

Adverse effects

• Hyperglycemia
• Hypertension
• Immunosuppression

12. Treatment of Heart Failure

Drugs used:

• Furosemide
• ACE inhibitors (Enalapril)
• Digoxin (if severe)

Supportive care:

• Bed rest
• Oxygen therapy

13. Treatment of Sydenham Chorea

Usually self-limited.

If severe:

Drugs:

• Valproic acid
• Haloperidol
• Carbamazepine

14. Secondary Prophylaxis (Prevention of Recurrence)

Essential because recurrent infections worsen heart damage.

Benzathine Penicillin G (preferred)

Dose

• 1.2 million units IM every 4 weeks

Children <27 kg

• 600,000 units IM every 4 weeks

Duration

| Patient Type | Duration |

| --------------------------------- | --------------------------------------------- |

| No carditis | 5 years or until age 21 |

| Carditis without residual disease | 10 years or until age 21 |

| Carditis with valvular disease | 10 years or until age 40 (sometimes lifelong) |

15. Complications

Major complications include:

1. Rheumatic Heart Disease

Permanent valvular damage.

Most affected valve:

• Mitral valve

Types

• Mitral regurgitation
• Mitral stenosis
• Aortic regurgitation

2. Heart Failure

Due to severe carditis.

3. Arrhythmias

• Atrial fibrillation

4. Recurrent Rheumatic Fever

Occurs if prophylaxis is not taken.

16. Prognosis

Depends mainly on cardiac involvement.

Good prognosis if:

• No carditis
• Early treatment

Poor prognosis if:

• Severe carditis
• Recurrent episodes
• Valvular damage

17. Prevention

Primary Prevention

Treat streptococcal throat infections promptly.

Drug:

• Penicillin for 10 days

Secondary Prevention

Long-term penicillin prophylaxis to prevent recurrence.

Key Points (Exam Focus)

• ARF occurs 2–3 weeks after streptococcal pharyngitis
• Jones criteria used for diagnosis
• Migratory polyarthritis most common feature
• Carditis most serious complication
• Mitral valve most commonly affected
• Benzathine penicillin used for eradication and prophylaxis
• Recurrent attacks lead to rheumatic heart disease

If you want, I can also give:

• MCQs on Acute Rheumatic Fever (exam level)
• FAQ JSON for your Medical Knowledge Hub website
• Short exam revision notes for ARF (very high-yield for paediatrics).