Scarlet Fever

Aka: Scarlet Fever, Second Exanthem of Childhood

1. Pathophysiology
   1. Occurs in Group A beta-hemolytic streptococcal (GAS) infection (typically Streptococcal Pharyngitis)
   2. Some GAS strains produce streptococcal pyrogenic exotoxin
      1. Patients with hypersensitivity to the toxin may develop a rash
2. Epidemiology
   1. Occurs in 10% of Streptococcal Pharyngitis cases
3. Symptoms
   1. Fever
      1. Peaks on Day 2
      2. Returns to normal on Day 5-7
   2. Chills
   3. Headache
   4. Vomiting
   5. Pharyngitis
4. Signs
   1. Forehead and cheeks appear flushed
   2. Circumoral pallor and sparing of rash
   3. Pharyngitis
      1. Tonsils are hyperemic and edematous, with exudate
      2. Throat is inflamed and covered by a membrane
      3. Palatal Petechiae may be present
   4. Strawberry Tongue
      1. Fine Papules on Tongue surface
      2. Tongue dorsum may appear with a white exudate and projecting edematous papillae
   5. Sandpaper Rash
      1. Onset with 12-72 hours after fever
      2. Coalescing, blanching erythematous Macules (may appear Sunburn-like)
      3. Fine papular or punctate lesions
         1. Texture of coarse sandpaper
      4. Rash distribution
         1. Starts on upper trunk
         2. Rash distribution generalizes within 24 hours
      5. Rash may affect flexor creases (Pastia lines) in the axillae, antecubital, groin and neck
         1. Pastia lines due not typically blanche
      6. Rash spares the palms and soles
         1. However, Desquamation of palms and soles may occur
   6. Desquamation
      1. Follows rash fading after several weeks
      2. Desquamation of face, skin folds, hands and feet
      3. Desquamation may last up to 6 weeks
5. Labs
   1. Streptococcal Rapid Antigen Test
   2. Throat Culture
      1. Used to confirm a negative rapid antigen test
   3. Antistreptolysin O titer (ASO Titer)
      1. Confirms diagnosis, but not typically helpful in acute disease
6. Differential Diagnosis
   1. Staphylococcal Scalded Skin Syndrome
   2. Kawasaki's Disease
      1. Also with Desquamation of palms and soles as well as strawberry Tongue
7. Management
   1. See Group A Streptococcal Pharyngitis for management
8. References
   1. Allmon (2015) Am Fam Physician 92(3): 211-6 [PubMed]