Diphtheria is an acute, toxin-mediated disease caused by toxigenic strains of Corynebacterium diphtheriae. The disease affects mucous membranes of the respiratory tract (respiratory diphtheria), skin (cutaneous diphtheria), and occasionally mucous membranes at other sites (eyes, ears or vagina). Cutaneous and nasal diphtheria are localized infections that are rarely associated with systemic toxicity


  • Symptoms of respiratory diphtheria have a gradual onset and include mild fever (rarely > 38 °C), malaise, sore throat, difficulty in swallowing, loss of appetite and (with laryngeal involvement) hoarseness. Within 2–3 days, a firmly adherent, grey membrane forms over the mucous membrane of the tonsils and pharynx, or both.
  • In severe cases, cervical lymphadenopathy and soft-tissue swelling in the neck give rise to a “bull-neck” appearance. Extensive membrane formation may result in life-threatening or fatal airway obstruction. Diphtheria toxin can cause serious, life-threatening, systemic complications, including myocarditis and neuritis

Infectious agents

C. diphtheriae is the bacterial agent that causes diphtheria.

Mode of Transmission

Transmission is by contact (usually direct) with the respiratory droplets of a carrier, discharges from skin lesions, or contaminated objects (uncommon). In rare cases, the disease may be transmitted through foodstuffs (e.g. raw milk has served as a vehicle).


  • Ensuring high population immunity through vaccination (primary prevention)
  • Rapid investigation and treatment of contacts (secondary prevention of spread)
  • Early diagnosis and proper case management (tertiary prevention of complications and deaths).


  1. WHO vaccine-preventable diseases: monitoring system — 2008 global summary. Geneva, World Health Organization (WHO), 2008 (WHO/IVB/2008) (http://www.who.int/immunization/ documents/WHO_IVB_2008/en, accessed 9 August 2010).
  2. Immunization surveillance, assessment and monitoring (diphtheria), WHO, 2009 (http://www.who.int/immunization_monitoring/diseases/diphteria/en/index.html, accessed 5 October 2010).

Further reading

Chapter 5. Diphtheria. In: Epidemiology and prevention of vaccine preventable diseases [The Pink Book], updated 11th ed. Atlanta, Centres for Disease Control and Prevention (CDC), 2009 (http://www.cdc.gov/vaccines/Pubs/pinkbook/pink-chapters.htm, accessed 10 August 2010).