Updated: 12/11/2018

Acute Rheumatic Fever

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Introduction
  • Overview
    • acute rheumatic fever is a systemic reaction following Strepptococcal pharyngitis which causes a characteristic rash and migratory arthritis that involves multiple large joints
      • treatment is oral antibiotics and anti-inflammatories
  • Epidemiology
    • incidence
      • 500k new cases per year worldwide
    • demographics
      • children 5-15 years of age
      • lower socioeconomic status
      • developing countries
  • Pathophysiology 
    • molecular biology
      • autoimmune reaction within 1-4 weeks following Group A beta-hemolytic Streptococcus pyogenes pharyngitis
      • molecular mimicry
        • antibodies to M protein of GAS causing an inflammatory response to synovium, myocardium, and basal ganglia cells
Presentation
  • Symptoms
    • rash
    • joint pain and refusal to bear weight
  • Physical exam
    • arthritis
      • red, swollen joints predominantly if the lower extremities, migratory
    • rash
      • erythema marginatum (pink rash on trunk and extremities that spares the face) 
    • other
      • subcutaneous nodules on upper extremity extensor surfaces
      • chorea
      • carditis, first-degree heart block (prolonged PR interval)
Imaging
  • Radiographs
    • may show effusion but often unremarkable   
  • Ultrasound/MRI
    • equivocal cases where concern remains for septic arthritis   
  • Echocardiogram
Lab Studies 
  • Serum labs
    • antistreptolysin O titers elevated in 80%
    • peripheral blood leukocytosis
    • inflammatory markers
      • ESR elevated
      • CRP elevated
  • Synovial Fluid Analysis
Condition WBC (cells/mL) PMNs (%)
Normal <200 <25%
Effusion from trauma <5,000 <25%
Toxic synovitis 5,000-15,000 <25%
Acute rheumatic fever 10,000-15,000

50%

JRA 15,000-80,000 75%
Septic arthritis >50,000 >75%
 
 Differential 
  • Lyme disease
    • positive Lyme titers
  • Septic arthritis
    • purulent synovial fluid, elevated cell count
  • Reiter/Reactive arthritis
    • specific rheumatologic labs will be positive (HLA-B27)
  • Juvenile Rheumatoid Arthritis
    • specific rheumatologic labs will be positive (RF and ANA)
  • Gout/Pseudogout
    • synovial fluid positive for MSU or CPPD crystals
Diagnosis 
  • Diagnosis based on Revised Jones criteria
    • preceding Strep infection with 2 major criteria or 1 major and 2 minor criteria
      • major criteria
        • carditis
        • polyarthralgia
        • chorea
        • erythema marginatum
        • subcutaneous nodules
      • minor criteria
        • fever
        • arthralgia
        • prior rheumatic fever
        • increased ESR
        • prolonged PR interval (First degree heart block)
        • prior Group A Strep infection
Treatment
  • Nonoperative 
    • oral antibiotics and anti-inflammatories 
      • indications
        • acute infection confirmed by Modified Jones criteria
        • arthralgias and/or fever
      • modalities
        • antibiotics
          • Penicillin 250mg PO BID x10 days (or erythromycin if penicillin-allergic)
          • Penicillin monthly x10 years to prevent rheumatic fever recurrence
        • anti-inflammatories
          • naprosyn more commonly used
          • salicylates used historically but concern for liver derangement deters use
Complications
  • Chronic rheumatic heart disease
 

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