Scarlet fever is caused by GAS strains lysogenized by a temperate bacteriophage that specifies production of pyrogenic exotoxin resulting in an erythematous rash, circumoral pallor, and strawberry tongue [1].
Scarlet fever used to be a frightening disease, but during the past few decades it seems to have had a mild course in the Western world. However, since the mid-1980s a worldwide increase in the incidence of severe group A streptococcal disease has been reported, including rheumatic fever, cellulitis, necrotizing fasciitis and other invasive forms. These serious infections were reported as being associated with the reappearance of M1 and M3 strains and the production of pyrogenic exotoxins A and B although subsequently other exotoxins have also been implicated. Food-borne epidemics (especially carried by milk) were common before pasterurization and were usually caused by group A streptococci, but groups C and G streptococci were also implicated on occasion. Food-borne infection can cause epidemic outbreaks of streptococcal infections such as scarlet fever and pharyngitis.
When the infecting strain produces one of the so-called pyrogenic (or erythrogenic) exotoxins, scarlet fever may be a complication of streptococcal pharyngitis. Although there are no scarlatinogenic streptococcal types the disease has a higher prevalence in streptococcal infections caused by M types 1, 3, 4, 6, 12, 18, 22 and 66. Group A streptococci are the main causative agents in scarlet fever, but streptococci of groups C and G are isolated from a small number of patients [2].
Scarlet fever used to be a frightening disease, but during the past few decades it seems to have had a mild course in the Western world. However, since the mid-1980s a worldwide increase in the incidence of severe group A streptococcal disease has been reported, including rheumatic fever, cellulitis, necrotizing fasciitis and other invasive forms. These serious infections were reported as being associated with the reappearance of M1 and M3 strains and the production of pyrogenic exotoxins A and B although subsequently other exotoxins have also been implicated. Food-borne epidemics (especially carried by milk) were common before pasterurization and were usually caused by group A streptococci, but groups C and G streptococci were also implicated on occasion. Food-borne infection can cause epidemic outbreaks of streptococcal infections such as scarlet fever and pharyngitis.
When the infecting strain produces one of the so-called pyrogenic (or erythrogenic) exotoxins, scarlet fever may be a complication of streptococcal pharyngitis. Although there are no scarlatinogenic streptococcal types the disease has a higher prevalence in streptococcal infections caused by M types 1, 3, 4, 6, 12, 18, 22 and 66. Group A streptococci are the main causative agents in scarlet fever, but streptococci of groups C and G are isolated from a small number of patients [2].
Scarlet fever presents as a characteristic erythematous, blanchable "sandpaper-like" rash formed by tiny papules, and is caused by streptococcal pyrogenic exotoxins A, B, and C. Along with typical pharyngitis symptoms, the scarlatiniform rash begins on day 2 or 3 of illness on the trunk and spreads to the extremities, sparing the palms and soles. Patients may also present with circumoral pallor, strawberry tongue, and Pastia’s lines, an accentuation of the rash within skin creases. Desquamation of the palms and soles sometimes follows resolution of the scarlet fever rash on day 6 to 9 of illness [3].
References:
Lydyard Peter M, et al. 2010. Case Studies in Infectious Disease. New York: Garland Science.
Cohen Jonathan, et al. 2004. Cohen & Powderly: Infectious Diseases 2nd Edition. New York: Elsevier.
Skolnik Neil S. 2008. Essential Infectious Disease Topics for Primary Care. New Jersey: Humana Press.