Scarlet fever is caused by strains of Streptococcus pyogenes producing an erythrogenic exotoxin.
After an incubation period of up to 6 days, and evidence of a sore throat or wound tenderness at the site of entry, a diffusely red, erythematous eruption develops with tiny red papules within.
Within two weeks the eruption fades with a fine desquamation. The tongue is characteristically swollen with papillary accentuation, the so called strawberry tongue.
The eruption is followed by a rise in antistreptolysin O titre.
- Treatment with antistreptococcal antibiotics for 10 days such as penicillin G is indicated, as the endotoxin can also harm internal tissues such as the myocardium.
- Because of the possibility of myocardial and renal toxicity, patients should be followed carefully.