Scarlet fever is a syndrome caused by a Group A streptococcal toxin. It is characterized by the scarlatiniform rash. Streptococci are gram-positive cocci that grow in chains.
Most streptococci excrete hemolyzing enzymes and toxins.
Erythrogenic toxins cause the rash of scarlet fever. The erythema-producing toxin was discovered by Dick and Dick in 1924. Group A streptococci are normal inhabitants of the nasopharynx. Scarlet fever usually is associated with pharyngitis but, in rare cases, follows streptococcal infections at other sites. The incubation period for Scarlet Fever ranges from 12 hours to 7 days.