| epidemiology of diphtheria in south dakota. | respiratory diphtheria was one of the most common causes of death among children in the pre-vaccine era. since the introduction of diphtheria toxoid vaccine in 1920s, and its widespread use by the late 1940s, diphtheria became increasingly rare in the united states. however, through the 1970s diphtheria remained endemic in some states, with reported incidence rates > 1.0 per million population in six states (alaska, arizona, montana, new mexico, south dakota, and washington). starting in 1980, l ... | 2000 | 10932611 |