Rheumatic fever

Question 1

what causes acute rheumatic fever

Answer 1

• systemic complication due to group A beta-hemolytic streptococci
• affects children 2-3 weeks after strep throat
• caused by molecular mimicry, bacterial M protein resembles human tissue

Question 2

how is the acute Rheumatic Fever diagnosed?

Answer 2

JONES criteria
- evidence of prior group A beta-hemolytic strep infection (ASO or anti-DNase B titre)
- minor criteria (fever and elevated ESR)
- major critieria 
Joints - migratory polyarthritis
O - Heart - pancarditis
Nodules
Erythema marginalitis - nodular rash
Symihems corhea

Question 3

explain the pancarditis caused by acute rheumatic fever

Answer 3

endocarditis - tiny vegetations especially of mitral valves

myocarditis - ashoff body –> focus of chronic inflammation - fibrinoid (degenerated collagen) + giant cells –> anischow cells (histocytes with catapillar nucleus) –> most common cause of death in acute phase

pericarditis - friction rub

Question 4

how does acute rheumatic fever become chronic?

Answer 4

acute attack resolves but may progress to chronic disease

• repeated exposure to group A beta hemolytic strep results in release pf acute phase
• increased risk of chronic rheumatic valvular disease

Question 5

explain chronic rheumatic valvular disease

Answer 5

• valve scarring that results from rheumatic fever
  results in stenosis - tighten - hard to push through
• almost always involves mitral valve –> thickening of chordae tendinae and cusps
• occasionally involves aortic valve –> fusion of commissures
• other valves less involved
• complication is endocarditis