Group a streptococcal disease in the 1990s: New clues to pathogenesis

In the past decade, a resurgence of serious illness due to group A Streptococcus has occurred. After declining in incidence for more than 50 years, acute rheumatic fever reappeared in the United States in several locations in the mid-1980s. In the late 198Os, streptococcal toxic shock syndrome was recognized as an uncommon, but life-threatening form of infection manifested by shock and multiorgan failure. More recently, attention has focused on cases of streptococcal necrotizing fasciitis. The apparent global increase in the incidence of serious group A streptococcal disease syndromes has renewed interest in the epidemiology and pathogenesis of streptococcal infection and its sequelae. Recent studies implicate the dissemination of virulent strains, particularly the Ml and M3 serotypes, in the upswing of invasive disease. Pyrogenic exotoxins-the toxins responsible for scarlet fever-appear to play a pathogenic role in streptococcal toxic shock syndrome, perhaps through their T-cell stimulatoty activity as superantigens.