diphtheria

Introduction

Diphtheria (Greek for tanned hide)

Etiology

• Corynebacterium diphtheriae

Epidemiology

• humans are the only known reservoir
  • asymptomatic carriers may act as reservoir
• transmission
  • airborne contact
  • direct contact with respiratory secretions or skin exudate
• in the 19th century, diphtheria had a high fatality rate, especially in children
• diptheria is now rare due to an effective vaccine first introduced in 1880
• 2 cases in USA in 2001
• case of cutaneous diphtheria reported in a fully vaccinated child visiting Sierra Leone
• consider cutaneous diphtheria in travelers with wound infections returning from diphtheria-endemic countries

Pathology

• severe inflammation that can form a membranous coating, with formation of a thick fibrinous exudate of the mucous membrane of the pharynx, the nose & sometimes the tracheobronchial tree.
• the diphtheria toxin produces a degeneration of peripheral nerves, heart muscle & other tissues

Clinical manifestations

• pharyngitis with gray membrane in tonsillar regions
• cervical lymphadenopathy
• dysphagia
• weakness
• fever
• carriers may be asymptomatic
• cutaneous diphtheria can appear as nonhealing, well-demarcated cutaneous ulcers (images)

Laboratory

• complete blood count: leukocytosis
• throat culture plated on Loeffler's or tellurite (Tinsdale) selective media
• culture of skin ulcer
• see ARUP consult

Management

• diphtheria antitoxin within 48 hours
• prophylaxis
  • most US citizens are immunized as children
  • immunity may diminish, especially in the elderly; immunization is suggested every 10 years
• cutaneous diphtheria responds to clarithromycin

More general terms

• bacterial infection

Additional terms

• Corynebacterium diphtheriae
• diphtheria CRM197 protein conjugate vaccine
• diphtheria toxoid