I n past centuries, group A streptococci (S1reptcXoccus pyogenes) were among the most common causes of mortalio in hxwns, panicularly in childhood. bur by the middle of this centu. y severe S. lwgenes infections were rare in the devclopeu’countries: Jf Northern Europe and ‘4merica’. While ac!~~, I~~ cIc reduction in come previously devastating group A streptococcaI diseases, such as puerperal sepsis (childbirth fever), can be attributed fo improved hygiene, changes in odms are kis easily explained’. For example, a sharp redax.. in the severity of scarlet fever wasaIreadynuedintbemiddk