Rheumatic Fever

Rheumatic Fever

Rheumatic fever is an immune-mediated inflammatory reaction that occurs following an infection with Group A streptococcus (GAS), typically after a period of 2-4 weeks. The condition most commonly affects children between 5 and 15 years old. In the UK, it is now rare, but due to global travel and migration, it remains an important diagnosis to consider. The World Health Organisation (WHO) and a collaborative effort led to the most recent update of the Jones criteria in 2015, which are used for diagnosis.

Diagnosis: Updated Jones Criteria (2015)

The diagnosis of acute rheumatic fever (ARF) requires evidence of a preceding GAS infection plus either two major criteria or one major and two minor criteria. Evidence of a preceding streptococcal infection includes a recent scarlet fever episode, a positive throat swab for GAS, or a raised streptococcal antibody titre (ASOT or anti-DNAase B).

Major Criteria

• Carditis: This is a key feature and can manifest as myocarditis, pericarditis, or endocarditis, often presenting with a new or changing heart murmur.

• Polyarthritis: A hallmark of ARF, characterised by a migratory inflammation of the large joints (e.g., knees, ankles, elbows). The inflammation is typically very painful but self-limiting.

• Sydenham’s Chorea: A neurological manifestation that occurs late in the disease, involving jerky, involuntary movements, and emotional lability.

• Erythema Marginatum: A rare, non-itchy rash with pink macules and a serpiginous, ‘snake-like’ border.

• Subcutaneous Nodules: Hard, pea-sized, painless nodules that are typically found over bony prominences.

Minor Criteria

The minor criteria are now stratified based on the population’s baseline risk of ARF. For the UK (a low-risk country):

• Fever: A temperature of $\ge$38.5°C.

• Arthralgia: Joint pain, but this cannot be used if arthritis is already counted as a major criterion.

• Raised Inflammatory Markers: A C-reactive protein (CRP) level of $\ge$3.0 mg/dL or an erythrocyte sedimentation rate (ESR) of $\ge$60 mm/h.

• ECG Findings: A prolonged PR interval, which indicates a conduction delay.

Acute Management

• Eradication of Strep: The acute infection should be treated with phenoxymethylpenicillin (Pen V) for 10 days. For those with a penicillin allergy, a macrolide such as erythromycin is used.

• Anti-inflammatory Agents:

  • Aspirin: A high-dose oral aspirin is used to manage the fever and arthritis.

  • Corticosteroids: For children with moderate to severe carditis, oral prednisolone is often added to the treatment regimen to reduce cardiac damage.

• Bed Rest: Children should be on bed rest until their inflammatory markers (ESR, CRP) normalise.

• Cardiac Support: If the child develops signs of heart failure, they may require diuretics and a referral to a paediatric cardiologist.

Secondary Prophylaxis

Preventing recurrent episodes is critical to avoid permanent cardiac damage, which is the most common cause of morbidity and mortality.

• Medication: The first-line choice is benzathine benzylpenicillin given via a deep intramuscular injection every 3 to 4 weeks. Oral penicillin V is an alternative for less severe cases.

• Duration: The duration of prophylaxis depends on the severity of the initial episode:

  • Lifelong Prophylaxis: Recommended for patients who had ARF with evidence of carditis, especially if there is residual valvular heart disease.

  • At least 10 years or until 21 years of age: For patients who had ARF without carditis.

Prognosis

Early diagnosis and consistent secondary prophylaxis are essential. The risk of cardiac damage increases with each recurrence of rheumatic fever. The key to prognosis is preventing repeat episodes of GAS infection to break the cycle of immune-mediated damage to the heart valves.