Rheumatic fever is an auto-immune systemic complication of lancefield group A beta-haemolytic streptococcal infection (typically a pharyngitis known as 'scarlet fever') that occurs 2 to 4 weeks post infection
Aetiology
Caused by an immune reaction to group A strep
Incidence in developed countries is low
Pathophysiology
2-4 weeks after a group A beta-haemolytic streptoccocus infection (scarlet fever) auto-antibodies are generated that not only target the streptoccocus but that also cross-react with the endocardium leading to valvular disease
This is known as molecular mimicry.
It is important to note that progressive damage commonly occurs in the years following acute rheumatic fever
Mitral valve disease occurs in 70% of cases and is the most common affected valve; aortic valves are involved in 40% (most commonly regurgitation), tricuspid valves in 10% and pulmonary valves in 2%
Clinical features
The Jones criteria is used to aid diagnosis
Diagnosis is considered likely if:
Evidence of recent streptococcal infection e.g. history of scarlet fever, positive throat swab
Plus 2 major criteria OR 1 major and 2 minor criteria
Major Jones criteria
Arthritis
Pancarditis - tachycardia, new murmur, or a new conduction defect
Sydenham's chorea - neurological disorder consisting of abrupt, non-rhythmic, involuntary movements along with muscular weakness and emotional disturbance
Erythema marginatum - geographical pink/red, nonpruritic rash involving mainly the trunk, thighs and arms
Subcutaneous nodules - firm, mobile painless lesions on extensor surfaces
Minor Jones criteria
Fever
Arthralgia (if arthritis does not meet major criterion)