Acute Rheumatic Fever- An immune mediated disease

Epidemiology, Causative Agent, Pathophysiology:

Acute Rheumatic Fever (ARF) is a multisystem disorder and develops as a complication of untreated Group-A beta-hemolytic Streptococcal throat infection. Though it is rare in Western Europe and North America, remain endemic in parts of Asia, Africa & South America.
ARF usually affects children (commonly 5-15 years of age) or young adults.
Antibody produces against a specific strain of Group- A Streptococci cross-reacts with cardiac myosin and sarcolemmal membrane protein.
It causes inflammation of different layers of heart muscle as well as joints and skin. Sometimes granulomatous nodules may be found throughout the heart, which is known as "Aschoff nodule", a pathognomic feature of Rheumatic fever.

Clinical Presentation:

Usually, patient experienced with fever, anorexia (loss of appetite), lethargy (lack of energy), shifting non-deforming polyarthritis (75-80% of cases), palpitation and chest pain (due to Carditis), 2-3 weeks after an episode of a Streptococcal sore throat. Sometimes the patient may give no history of a sore throat.
The patient may also develop rashes and neurological changes.

Common Joints Involvement:

Commonly large joints like ankle, knee, elbow joints but rarely hip joints may involve.

Clinically Diagnosis is made on the basis of Revised Jones Criteria, which includes some Major and Minor criteria.

Major Criteria:

  1. Carditis
  2. Migratory polyarthritis (inflammation of 5 or more joints, which shifted from one joint to another).
  3. Sydenham's Chorea (also called St Vitus dance): it is the late but definitive feature of RF, and characterized by purposeless involuntary movement of hand, feet or face.
  4. Erythema marginatum: painless lesions with red margin but the centre is fade.
  5. Subcutaneous nodule (nodular swellings beneath the skin).
title with image of leg and trunk sign of ARF


Minor Criteria:

  1. Fever
  2. Arthralgia
  3. Raised acute phase reactant: ESR, CRP
  4. First degree A-V block
Associated with evidence of Streptococcal infection.

Investigation:

For diagnosis of Streptococcal Infection:

  • Throat swab culture
  • ASO (Antistreptolysin O) titer

For diagnosis of Carditis:

  • Chest X-ray
  • ECG
  • Echocardiography

Complications:

Rheumatic valvular heart disease. About 70% of cases Mitral is involved but Aortic valve, Tricuspid valve and Pulmonary valve can also be affected.

Prevention: 

Primary prevention: History of a recurrent sore throat or pharyngitis and raised ASO titre should be treated with full course oral antibiotic therapy.
Secondary Prevention: Should be treated with either intramuscular injection of antibiotic Penicillin at every 3-4weeks or daily oral antibiotic therapy, for 5 years or up to 21 years of age, which one is longer.
If the patient develops valvular heart, then prophylaxis should be lifelong.

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