Definition:

Diphtheria is a contagious and potentially life-threatening childhood disease caused by Corynebacterium diphtheriae. In industrialized countries, immunization against diphtheria became widespread in the 1940s and the incidence of the disease markedly decreased. However, diphtheria still remains endemic in several regions including Africa, India, Bangladesh, Vietnam, the tropics, and South America. Moreover, a large proportion of adults in industrialized countries are now susceptible to diphtheria because the protection by vaccine does not last for long time unless periodic booster is given.