Scarlet fever

Scarlet fever is a reaction to erythrogenic toxins produced by Group A haemolytic streptococci (usually Streptococcus pyogenes). It is more common in children aged 2 - 6 years with the peak incidence being at 4 years.

Scarlet fever has an incubation period of 2-4 days and typically presents with:

• fever
• malaise
• tonsillitis
• 'strawberry' tongue
• rash - fine punctate erythema ('pinhead') which generally appears first on the torso and spares the face although children often have a flushed appearance with perioral pallor. The rash often has a rough 'sandpaper' texture. Desquamination occurs later in the course of the illness, particularly around the fingers and toes

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Diagnosis

• a throat swab is normally taken but antibiotic treatment should be commenced immediately, rather than waiting for the results

Management

• oral penicillin V
• patients who have a penicillin allergy should be given azithromycin
• children can return to school 24 hours after commencing antibiotics
• scarlet fever is a notifiable disease

Complications

• otitis media: the most common complication
• rheumatic fever: typically occurs 20 days after infection
• acute glomerulonephritis: typically occurs 10 days after infection