Diphtheria Outbreaks in Immunized Populations

Abstract

Studies of an outbreak of clinical diphtheria in Sweden serve to make two points.¹ The first involves a molecular marker of epidemiologic and possibly pathogenetic importance. The second concerns the possibility of recurrent outbreaks of diphtheria in populations with high rates of immunization.In this issue of the Journal, Rappuoli and his colleagues report their use of a genetic probe to identify one or more copies of a DNA sequence in the Corynebacterium diphtheriae genome. The hybridization pattern of this 1500-kb DNA sequence, called an insertion element, remains constant and recognizable in strains isolated in a single epidemiologic setting. . . .