Rheumatic Fever

Rheumatic fever is an inflammatory disease that can develop as a complication of inadequately treated strep throat or scarlet fever, both caused by group A streptococcus bacteria. It can affect the heart, joints, skin, and brain.

Causes

  • Group A Streptococcus Infection: Usually follows 1-5 weeks after a strep throat infection. Not all strep infections lead to rheumatic fever, and susceptibility varies among individuals.

Diagnosis

  • History:
    • Recent Infection: Throat infection or scarlet fever 2-4 weeks prior.
    • Symptoms: May include fever, joint pain and swelling, involuntary movements (Sydenham’s chorea), skin rash (erythema marginatum), and nodules under the skin.
  • Physical Examination:
    • Joints: Swelling, redness, and pain, typically in large joints like knees and elbows.
    • Heart: Murmurs, indicating potential valvular damage.
    • Skin: Look for erythema marginatum and subcutaneous nodules.
    • Neurological: Assess for Sydenham’s chorea – involuntary, irregular movements of the face and extremities.
  • Investigations:
    • Throat Culture or Rapid Strep Test: To identify recent strep infection.
    • Blood Tests:
      • Elevated streptococcal antibodies (ASO and Anti-DNAse B)
      • Increased inflammation markers (ESR, CRP).
    • Echocardiogram: To evaluate heart function and structure.
    • Electrocardiogram (ECG): If heart involvement is suspected.
  • Jones Criteria:
    • The diagnosis of rheumatic fever is based on the revised Jones Criteria, which include major and minor criteria.
    • Major criteria include
      • carditis
      • arthritis,
      • subcutaneous nodules,
      • erythema marginatum rash
      • Sydenham chorea
    • Minor criteria include
      • prolonged PR interval on an ECG
      • arthralgia
      • fever
      • elevated CRP and ESR
    • A diagnosis of rheumatic fever is typically made if the patient meets two major criteria or one major and two minor criteria, in addition to evidence of a recent streptococcal infection.

Differential Diagnosis

  • Septic Arthritis: Joint infection causing similar joint symptoms.
  • Juvenile Idiopathic Arthritis: Chronic arthritis in children.
  • Viral Arthritis: Transient arthritis following viral infections.
  • Infective Endocarditis: Especially if there is heart involvement.
  • Systemic Lupus Erythematosus (SLE): SLE can cause arthritis, skin rashes, and other symptoms similar to those of rheumatic fever.

Management

  • Antibiotics: For existing strep infection and prophylaxis to prevent recurrence.
    • Benzathine benzylpenicillin IM 1.2 million units stat (10-20kg 0.6 million units) – every 21-28 days
  • Anti-inflammatory Treatment: High dose aspirin is used
    • Naproxen 500mg oral BD (10mg/kg for kids) until joint symptoms settled for 1-2 weeks
  • Corticosteroids: In severe cases, especially with carditis.
  • Bed Rest: During the acute phase, especially with carditis.
  • Long-term Antibiotic Prophylaxis: To prevent recurrent attacks, which can worsen heart damage.
  • Regular Monitoring: Especially cardiac follow-up due to the risk of chronic valvular heart diseases.
  • Heart Surgery: In cases of severe chronic valvular disease.
  • Long-Term Prophylaxis: After an episode of rheumatic fever, patients are usually prescribed long-term antibiotic prophylaxis to prevent recurrent streptococcal infections, which can trigger further episodes.
  • Preventive Measures: Public health measures to prevent streptococcal infections, particularly strep throat, are crucial to reducing the incidence of rheumatic fever.
  • Prognosis: Varies depending on the extent and severity of the complications, especially cardiac involvement. Early treatment can prevent or reduce the severity of these complications.

Duration of Penicillin Treatment

  • Age and Duration Since Last Attack:
    • In children and adolescents, prophylaxis is usually recommended until they reach adulthood, often until the age of 21 years or for a minimum of 5 years after the last attack, whichever is longer.
    • For adults, the duration may vary based on the time elapsed since their last rheumatic fever episode and their ongoing risk of exposure to Group A Streptococcus.
  • Presence of Cardiac Involvement:
    • If rheumatic fever has caused damage to the heart valves (rheumatic heart disease), longer-term or even lifelong prophylaxis may be necessary.
    • The decision for lifelong prophylaxis is often considered in patients with severe valve damage, those who have undergone valve surgery, or those with a history of recurrent rheumatic fever episodes.

In summary, rheumatic fever is a preventable sequela of strep throat, largely mitigated by timely and adequate treatment of streptococcal infections. It requires a high index of suspicion following a strep infection, especially in children, and management focuses on eradicating the infection, controlling inflammation, and preventing recurrence.