Which age group is most commonly affected by diphtheria?

Updated: Jan 18, 2019
  • Author: Bruce M Lo, MD, MBA, CPE, RDMS, FACEP, FAAEM, FACHE; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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Historically, diphtheria has been primarily a disease of childhood, affecting populations younger than 12 years. Infants become susceptible to the disease at age 6-12 months after their transplacentally derived immunity wanes. [17] Since the advent of diphtheria vaccination, cases of pediatric disease have declined dramatically. Recently, however, diphtheria has shifted into the adolescent and adult population, most notably in ages 40 and older accounting for most new cases. [12] This is primarily due to incomplete immunization status, including never being immunized, inefficient vaccine or response to vaccination, and not receiving a booster after previous vaccination. According to immunologic studies, one must have an antitoxin level of greater 0.1 IU/mL for adequate immunity. [18] Additionally, adolescents and adults may exhibit an atypical presentation of the disease, thus potentially obscuring the diagnosis. [8]

Immunization schedules have recently changed requiring a toxoid booster at age 11-12 and every 10 years thereafter. The toxoid booster, without tetanus, is approved for pregnant women if their antitoxin titers are less than 0.1 IU/mL. [18]

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