Introduction
Rheumatic fever develops following an immunological reaction to recent (2-6 weeks ago) Streptococcus pyogenes infection.
Epidemiology
- Incidence: 1.00 cases per 100,000 person-years
- Peak incidence: 6-15 years
- Sex ratio: 1:1
| <1 | 1-5 | 6+ | 16+ | 30+ | 40+ | 50+ | 60+ | 70+ | 80+ |
Pathophysiology
Pathogenesis
- Streptococcus pyogenes infection → activation of the innate immune system leading to antigen presentation to T cells
- B and T cells produce IgG and IgM antibodies and CD4+ T cells are activated
- there is then a cross-reactive immune response (a form of type II hypersensitivity) thought to be mediated by molecular mimicry
- the cell wall of Streptococcus pyogenes includes M protein, a virulence factor that is highly antigenic. It is thought that the antibodies against M protein cross-react with myosin and the smooth muscle of arteries
- this response leads to the clinical features of rheumatic fever
- Aschoff bodies describes the granulomatous nodules found in rheumatic heart fever
Clinical features
Symptoms
- Fever (90%)
- Sore throat (80%): This typically occurs 3 weeks before the other symptoms develop
- Joint pain (70%)
- Chorea (20%)
- Rash (10%): Erythema marginatum
Signs
- Murmur (50%)
- Pericardial rub (40%)
Investigations
Diagnosis
Diagnosis is based on evidence of recent streptococcal infection accompanied by:
Evidence of recent streptococcal infection
Major criteria
Minor criteria
*The latest iteration of the Jones criteria (published in 2015) state that rheumatic carditis cannot be based on pericarditis or myocarditis alone and that there must be evidence of endocarditis (the clinical correlate of which is valvulitis which manifests as a regurgitant murmur).
- 2 major criteria
- 1 major with 2 minor criteria
Evidence of recent streptococcal infection
- raised or rising streptococci antibodies,
- positive throat swab
- positive rapid group A streptococcal antigen test
Major criteria
- erythema marginatum
- Sydenham's chorea: this is often a late feature
- polyarthritis
- carditis and valvulitis (eg, pancarditis)*
- subcutaneous nodules
Minor criteria
- raised ESR or CRP
- pyrexia
- arthralgia (not if arthritis a major criteria)
- prolonged PR interval
*The latest iteration of the Jones criteria (published in 2015) state that rheumatic carditis cannot be based on pericarditis or myocarditis alone and that there must be evidence of endocarditis (the clinical correlate of which is valvulitis which manifests as a regurgitant murmur).