Inhibition of the scarlet fever exanthem in concurrent varicella and group A streptococcus infection.

An atypical scarlet fever exanthem was noted in a 5-year-old child with varicella complicated by secondary group A beta-hemolytic streptococcus pneumonia and empyema. The rash consisted of symmetrical, concentric, circular exanthem-free zones surrounding individual varicella vesicles. The possible role of virus-induced interferon in locally modifying the effect of streptococcal pyrogenic exotoxin is explored.