<prompt> Which serum is used for testing streptococcal pyrogenic toxin-Convalescent human serumSerum from patient of acute scarlet feverHorse serumNone of the above  <response>: Ans. is a i.e.. Convalescent human serum Tests related to pyrogenic toxin erythrogenic Dick toxin of streptococcuso There were two historical tests which were used :Dick test: Intraderma Injection of toxin in a child produces erythematous reaction if heshe is susceptible to scarlet fever.Schultz scharlton reaction : It was used as a diagnostic test for Scarlet fever. Blanching of erythematous rash is produced during scarlet fever on local injection of convalescent serum As serum from patient in convalescent phase has antibodies against this toxin 