Rheumatic Fever

Rheumatic fever is a delayed, autoimmune complication of group A Streptococcus (Streptococcus pyogenes) pharyngitis, occurring roughly two to four weeks after the initial throat infection.

It results from molecular mimicry, in which antibodies raised against streptococcal antigens cross react with host tissue in the heart, joints, skin, and central nervous system.

It remains a major cause of acquired heart disease in children and young adults in low and middle income settings, where access to prompt treatment of streptococcal pharyngitis is limited.

Recurrent episodes cause cumulative valvular damage, and it is this valvular scarring, known as rheumatic heart disease, that carries the long term morbidity and mortality burden.

Diagnosis is guided by the Jones criteria, which separate major and minor manifestations.

• The major criteria are carditis (endocarditis, myocarditis, or pericarditis, often presenting as a new murmur, particularly mitral regurgitation), polyarthritis (classically migratory, affecting large joints), Sydenham chorea (involuntary, irregular movements, often delayed in onset by weeks to months after the preceding infection), erythema marginatum (a evanescent, pink, serpiginous rash with central clearing, typically on the trunk and proximal limbs), and subcutaneous nodules (firm, painless, over extensor surfaces and bony prominences).

• The minor criteria include fever, arthralgia (which cannot be counted alongside polyarthritis as a major criterion in the same patient), elevated inflammatory markers (ESR or CRP), and a prolonged PR interval on ECG.

Diagnosis requires evidence of a preceding group A streptococcal infection, together with either two major criteria, or one major plus two minor criteria. A separate, lower threshold applies for recurrent episodes in a patient with known prior rheumatic fever.

Evidence of preceding streptococcal infection is sought through a positive throat culture or rapid antigen test (though these are frequently negative by the time rheumatic fever manifests, given the delay after the original infection), or, more usefully at this stage, elevated or rising anti-streptolysin O (ASOT) or anti-DNase B titres.

Inflammatory markers (ESR and CRP) support the diagnosis as minor criteria and help track disease activity.

ECG is essential, looking for a prolonged PR interval and any arrhythmia.

Echocardiography is required in all suspected cases, both to confirm carditis (which may be subclinical, detected only on echocardiography without an audible murmur) and to assess the severity of any valvular involvement, most commonly mitral regurgitation, less commonly aortic regurgitation.

Differentials include septic arthritis, reactive arthritis, juvenile idiopathic arthritis, systemic lupus erythematosus, viral myocarditis, and infective endocarditis, particularly when carditis is the presenting feature.

Eradication of the streptococcal infection is essential even if throat culture is now negative, using a single dose of intramuscular benzathine penicillin, or oral phenoxymethylpenicillin for ten days if intramuscular treatment is not feasible.

Anti-inflammatory treatment follows separately. Arthritis and fever generally respond well to high dose aspirin or another NSAID (naproxen is a commonly used alternative), continued until symptoms and inflammatory markers settle.

Moderate to severe carditis, particularly with heart failure, is treated with corticosteroids, though evidence for a mortality or long term valvular benefit is limited and steroids are used mainly for symptomatic and hemodynamic control in this context.

Heart failure arising from severe carditis is managed with standard heart failure therapy alongside the anti-inflammatory treatment above (see Heart Failure entry).

Sydenham chorea, when mild, may only require reassurance and supportive care; more significant chorea is treated with carbamazepine or sodium valproate, with antipsychotics reserved for severe, refractory cases.

Secondary prophylaxis is the cornerstone of long term management, given the markedly increased risk of recurrent rheumatic fever and progressive valvular damage with each subsequent episode.

Regular intramuscular benzathine penicillin, typically every three to four weeks, is continued for a minimum duration determined by the presence and severity of carditis: at least five years or until age twenty one for rheumatic fever without carditis, at least ten years or until age twenty five for rheumatic fever with carditis but no residual valvular disease, and lifelong for those with established valvular disease.

Referral: cardiology for all confirmed or suspected carditis, given the need for echocardiographic assessment and monitoring of valvular disease; neurology for significant chorea.