Scarlet fever

• Pathophysiology
  • Occurs in Group A beta-hemolytic streptococcal (GAS) infection (typically Streptococcal Pharyngitis)
  • Some GAS strains produce streptococcal pyrogenic exotoxin
  • Patients with hypersensitivity to the toxin may develop a rash
• Epidemiology
  • Occurs in 10% of Streptococcal Pharyngitis cases
• Symptoms
  • Fever
    • Peaks on Day 2
    • Returns to normal on Day 5-7
  • Chills
  • Headache
  • Vomiting
  • Pharyngitis
• Signs
  • Forehead and cheeks appear flushed 
  • Circumoral pallor
  • Pharyngitis
    • Tonsils are hyperemic and edematous, with exudate
    • Throat is inflamed and covered by a membrane
    • Palatal Petechiae may be present
  • Strawberry Tongue
    • Fine Papules on Tongue surface
    • Tongue dorsum may appear with a white exudate and projecting edematous papillae
  • Rash
    • Onset with 12-72 hours after fever
    • Coalescing, blanching erythematous Macules (may appear Sunburn-like)
    • Fine papular or punctate lesions
      • Texture of coarse sandpaper
    • Rash distribution
      • Starts on upper trunk
      • Rash distribution generalizes within 24 hours
    • Rash may affect flexor creases (Pastia lines) in the axillae, groin and neck
      • Pastia lines due not typically blanche
    • Rash spares the palms and soles
      • However, Desquamation of palms and soles may occur
  • Desquamation
    • Follows rash fading after several weeks
    • Desquamation of face, skin folds, hands and feet
    • Desquamation may last up to 6 weeks
• Labs
  • Streptococcal Rapid Antigen Test
  • Throat Culture
    • Used to confirm a negative rapid antigen test
  • Antistreptolysin O titer (ASO Titer)
    • Confirms diagnosis, but not typically helpful in acute disease

• Differential Diagnosis
  • Staphylococcal Scalded Skin Syndrome
  • Kawasaki’s Disease
    • Also with Desquamation of palms and soles as well as strawberry Tongu

Treatment

• Penicillin or amoxicillin is the first-line treatment.
• If the affected person has an allergy to penicillin, a first-generation cephalosporin, clindamycin, or erythromycin can be used.
• The use of antibiotics has reduced the morbidity and mortality of scarlet fever when compared to the early 20th century when the mortality was approximately 30%.