Acute Rheumatic Fever

Epidemiology

• 4 million children affected worldwide
• 94% of cases are in developing countries
• Most common in tropical countries with no seasonal variation
• More common in females

Pathophysiology

Streptococcus pyogenes is a gram-positive cocci and it produces two cytolytic toxins: streptolysin O and S.

Rheumatogenic strains of GAS contain M proteins in their cell wall and are immunogenic. B cells are stimulated to produce anti-M protein antibodies against the infection which also cross react with other tissues e.g. that of the heart (causing rheumatic heart disease), brain, joints and skin leading to a constellation of multiorgan signs and symptoms. This is also exacerbated by production of activated cross reactive T cells.

Risk Factors

• Children and young people
• Poverty
• Overcrowded and poor hygiene places
• Family history of rheumatic fever
• D8/17 B cell antigen positivity

Clinical Features

The Revised Jones Diagnostic Criteria (below) describes the key clinical features that may be present. In addition to this, you may elicit from the history that they had a recent sore throat or scarlet fever. Also, in severe acute rheumatic failure, a heart murmur might be heard on examination and it is most commonly the mitral valve, which is affected.

Diagnostic Requirements

Positive throat culture for Group A β-haemolytic streptococcus or elevated anti-streptolysin O (ASO) or anti-deoxyribonuclease B (anti-DNASE B) titre.

AND

2 major criteria OR 1 major and 2 minor criteria present for initial ARF. (Same criteria for recurrent ARF plus can also be just 3 minor criteria)

Major Criteria (SPECS)

• Sydenham’s chorea
• Polyarthritis
• Erythema marginatum (figure 1: more examples at dermnetnz)
• Carditis
• Subcutaneous nodules

Minor Criteria (CAPE)

• CRP or ESR – Raised acute phase reactant
• Arthralgia
• Pyrexia/Fever
• ECG – Prolonged PR interval

*Joint (arthritis or arthralgia) and cardiac (carditis or prolonged PR interval) manifestations can only be counted once, not twice, as either a major or a minor criterion.

*Slight variation of criteria for high risk population

By TeachMeSeries Ltd (2026)

Figure 1: Erythema Marginatum 

Differential Diagnosis

Thera are numerous differential diagnoses to ARF, but below are examples of a few differentials and their distinguishing features.

Investigations

• Bloods: ESR, CRP, FBC (WBC),
• Blood cultures to exclude sepsis
• Rapid Antigen Detection Test
• Throat culture: may be negative by the time rheumatic fever symptoms occur
• Anti-streptococcal serology: ASO and anti-DNASE B titres
• ECG: prolonged PR interval
• CXR if carditis is suspected: congestive heart failure may be seen in ARF due to valvular damage
• Echocardiography

Management

Initial management in confirmed rheumatic fever

1. Antibiotics e.g. benzathine benzylpenicillin (1^st choice due to its long acting property, serving the purpose of GAS eradication and secondary prophylaxis), phenoxymethylpenicillin , amoxicillin. In confirmed penicillin allergy, alternatives include cephalosporins (avoid in IgE mediated penicillin allergy and anaphylaxis), macrolides and clindamycin (4)
2. Aspirin or NSAIDs e.g. naproxen or ibuprofen
3. Assess for emergency valve replacement
4. In severe carditis (e.g. congestive cardiac failure or 3^rd degree heart block) glucocorticoids and diuretics may be required

Definitive and Long‐term management

Secondary prophylaxis with intramuscular Benzathine benzylpenicillin every 3-4 weeks, oral Phenoxymethylpenicillin twice daily, oral sulfadiazine daily, or oral azithromycin (in penicillin allergy) (4)

Complications and Prognosis

• 2% of the population can get permanent damage to heart valves and chronic rheumatic heart disease
• With treatment ARF should resolve within 2 weeks but cardiac inflammation may take months to resolve fully and thus, it is common for patients to relapse within this time

References