Rheumatic fever Flashcards
what is rheumatic fever?
common infectious disease until mid 20th century, incidence decline in developed countries but is common in developing countries and in indigenous populations
what has caused the fall in rheumatic fever?
penicillin
reduced virulence in strains of the streptococcus infection
improved living conditions
where is rheumatic fever common
areas of overcrowding and poor access to healthcare
higher incidence in winter
rare in developed countries
who does it affect?
typically school age children - median age = 10.4
rare before 3 and after 21
what countries/regions is it common?
indigenous populations of australia, new zealand, pacific island nations and south america
what causes rheumatic fever?
poverty overcrowding family history genetic factors caused by group A beta-haemolytic streptococci - most commonly those with the M antigen
pathogenesis of rheumatic fever
organ damage due to a type 2 hypersensitivity reaction - cross-linking of antibodies
antibodies against streptococcal M protein act against cardiac myosin
heart valves are infiltrated by T cells which are against cardiac myosin as they were activated by M antigen
mitral valve most commonly affected in acute rheumatic heart disease, but all can be affected
when do symptoms occur?
1-5 weeks after infection - e.g. after sore throat
this period is shorter in reoccurrence as there is a quicker immune response
what are the symptoms?
fever - 1 week arthritis neurological signs/symptoms - 30% of patients skin signs/symptoms cardiac signs/symptoms
symptoms: arthritis
often severe pain
unable to walk if lower limbs affected
usually asymmetrical
polyarthritis
neurological symptoms
syndenham’s chorea
tourette’s syndrome
symptoms cease during sleep
syndenham’s chorea
rapid purposeless movements
affecting face and upper limbs
skin symptoms
subcutaneous nodules
erythema marginatum
macular/papular rash on trunk and arms
face is spared
cardiac signs/symptoms
aortic regurgitation carey coombs' sign pericardial rub tachycardia endocarditis myocarditis
austin flint’s murmur
aortic regurgitation
carey coombs’ sign
characteristic soft diastolic murmur due to mitral valve involvement
signs on echo
mitral valve changes - 70%
aortic valve changes - 25%
tricuspid valve changes - 10%
pulmonary valve changes are rare
diagnosis
The Jones criteria
What is required for a diagnosis of rheumatic fever?
evidence of recent streptococcal infection
plus 2 major criteria or 1 major and 2 minor criteria
what counts as recent streptococcal infection?
scarlet fever
positive throat/wound swab
serological confirmed streptococcal infection - raised anti-streptolysin O titre of 200U/ml
Jones criteria: major criteria
arthritis signs of carditis - murmur and echo chorea subcutaneous nodules erythema marginatum/annulare
Jones criteria:minor criteria
fever
raised CRP/ESR
arthralgia - not a sign if arthritis already counted as a major sign
prolonged PR interval - not a sign if carditis already counted as a major sign
when to consider rheumatic fever
any patient with chorea or carditis that doesn’t have obvious cause
differential diagnoses
rheumatoid arthritis henoch-schonlein purpura reactive arthritis erythema nodosum infective endocarditis cardiomyopathy myocarditis drug reactions (metoclopramide)
