The bacterium Corynebacterium diphtheriae causes diphtheria. Usually C. diphtheriae multiply on or near the surface of the mucous membranes of the throat. C. diphtheriae spreads via three routes:

  • Airborne droplets. When an infected person's sneeze or cough releases a mist of contaminated droplets, people nearby may inhale C. diphtheriae. Diphtheria spreads efficiently this way, particularly in crowded conditions.
  • Contaminated personal items. People occasionally catch diphtheria from handling an infected person's used tissues, drinking from the person's unwashed glass, or coming into similarly close contact with other items on which bacteria-laden secretions may be deposited.
  • Contaminated household items. In rare cases, diphtheria spreads on shared household items, such as towels or toys.

You can also come in contact with diphtheria-causing bacteria by touching an infected wound.

People who have been infected by the diphtheria bacteria and who haven't been treated can infect nonimmunized people for up to six weeks — even if they don't show any symptoms.

Mar. 27, 2014