Rheumatic Fever in Children

Rheumatic Fever

·        Incidence:

o   Incidence has declined over last 50 years, from death rate of about 20/100,000 to 6/100,000

o   1 per 1000 people in NZ (highest rate in western world). 

o   Annual incidence in NZ per 100,000: European 0.1 – 0.3, Maori 6.1 – 11.3 (ie 50 – 100 times), Pacific Island 13.3 – 24.3 (ie 100-200 times). Pockets in Porirua, South Auckland

o   Acute attacks occur mainly between 5 – 15 years of age.  Peak 10 – 11 years.

·        Aetiology:

o   Incidence following strep throat is 0.3 % (sore throat for 1 week) to 3% (sore throat for 3 weeks) 

o   ?Some at ­ risk due to longer carriage of strep ® ­ antibody response 

·        Pathogenesis: Group A b-haemolytic streptococci infection (eg Streptococcus Pyogenes) ® cross reactive antibodies – substances in myocardium similar to strep antigens to significant inflammatory reaction in cardiac muscle ® acute rheumatic fever 1 – 5 weeks following infection (average 19 day latent period). 

·        Clinical features:

o   Carditis:

§  Endo +/- myo +/- peri

§  Usually mild in first attack

§  New left sided diastolic murmur: mitral and/or aortic regurgitation

§  Tachycardia

§  PR prolongation (may be buried in T wave) 

§  Cardiomegaly: due to valve dysfunction (® dilation) or myocarditis

o  Arthritis:

§  Migratory polyarthritis – as one joint starts to recover another flares

§  Usually large joints.  Can be red and swollen

§  Dramatic response to aspirin

§  Never permanent joint damage

o  Chorea (St Vitus Dance):

§  Sudden or gradual onset.  Acute onset chorea in a child only occurs in RF

§  Usually generalised, although can be focal

§  Deterioration at school, eg writing

§  Stops during sleep

§  Increased by anxiety/stress

§  Rare symptom.  Always resolves, after 2 – 3 weeks

o  Erythema Marginatum:

§  = Red rash around edge, centre normalises as it expands

§  Evanescent (comes and goes quickly)

§  Not itchy, blanches with pressure, mainly on trunk and proximal limbs

o  Subcutaneous nodules: small, painless, over bony prominences, RARE

·        Investigations:

o  Throat swab: +ive for strep in 15%

o  ESR usually > 100 (not if chorea or CHF)

o  CXR: looking for cardiomegaly

o  ECG: prolonged PR in 14%

o  Echocardiogram

o  Streptococcal titres

·        Diagnosis: 

o  Acute Phase: Jone‟s criteria: evidence of strep throat (­serum titres) plus 2 major or 1 major/2minor: 

§  Major criteria: carditis, migratory polyarthritis of major joints (75%), erythema marginatum (non pruritic, non painful), subcutaneous nodules, and chorea (later) 

§  Minor criteria: fever, arthralgia, ­acute phase proteins, c-reactive protein, ESR, ­PR interval

§  Also watch out for murmurs, arrhythmias (from focal fibrosis)

§  Very difficult to diagnose.  Always consider as differential in pyrexia of unknown origin 

o  Chronic Phase: recurring attacks magnify cardiac injury. Mitral and/or aortic stenosis progresses to congestive heart failure. Recurrent attacks make it worse ® ?long term prophylaxis

·        Treatment:

o  Eradicate streptococcus 

o  Aspirin: 75 mg/kg/day (¯inflammation)

o  Bed rest if cardiomegaly or CHF, others should avoid rigorous exercise

o  Steroids for acute treatment – but doesn‟t affect long term prognosis

o  Diazepam for chorea

·        Course:

o  Acute phase lasts 6 – 8 weeks, monitored by ESR

o  Dental check

o  Ongoing management:

§  Will get it again if they get another strep infection, and more severe 

§  Penicillin prophylaxis: 4 weekly IM benzathine penicillin until 18 if no cardiac damage (for life if damaged). 

§  Regular dental care. Prophylaxis for deep dental work (erythromycin or clindomycin – won‟t have any penicillin sensitive organisms on board)

§  Valves can recover

·        Macroscopic appearance: 

o  Acute (exudative and proliferative) phase: Pancarditis grossly visible in valves and pericardium. Valve leaflets have evenly spaced small 1 – 2 mm sterile/inflammatory (not infective) „verrucae‟ – small vegetations resulting from deposition of fibrin along edges of value. Verrucae resolve but Aschoff bodies (areas of necrosis surrounded by macrophages) organise and fibrose. Mitral valve always involved. Pericardium show non-specific serofibrinous (bread and butter) pericarditis similar to uraemia or acute MI

o   Chronic (healed) phase: Heals with organised fibrosis ® deformed valves (50% mitral, 50% mitral and aortic) and/or shortening/thickening/fusion of chordae tendinae. Subendocardial fibrosis ® fibrous plaque (McCallum‟s patch). Characteristic “fish mouth” stenosis ® atrial hypertrophy and LV atrophy. Aortic stenosis ® LV hypertrophy. May lead to murmurs or arrhythmias 

·        Microscopic appearance:

o   Exudative phase: fibrinoid necrosis with neutrophils, lymphocytes, plasma cells and macrophages 

o   Proliferative phase: Aschoff body in the myocardium is pathognomonic. Consists of central fibrinoid exudate/necrosis with aggregates of large mononuclear or multinuclear cells (Aschoff giant cells), fibroblasts, plasma cells, lymphocytes and oedema. Aschoff bodies may also be seen in perivascular spaces, joint capsules, tendons, subcutaneous tissues 

·        Susceptible to later valvular infection

·        Treatment: Possible surgical replacement of deformed valves