The name diphtheria was derived from the Greek root for leather, descriptive for the pharyngeal membrane that characterized the disease. Hippocrates clinically described it, and, in the 20th century, it has evolved from a major public health problem to a medical curiosity within the developed nations through the use of immunization measures. Diphtheria is an acute infectious disease caused by the gram-positive bacillus Corynebacterium diphtheriae. It is characterized by a primary lesion, usually within the respiratory tract, and more generalized symptoms caused by release and spread of bacterial exotoxins throughout the body. It most commonly affects children younger than 10 years.
Humans are the only known reservoir for C diphtheriae.
The primary modes of spread are via airborne droplets or contact with respiratory secretions or exudates from infected skin lesions. Fortunately, the widespread immunization of infants using diphtheria toxoid has made this infection extremely rare in developed nations. Diphtheria was the leading cause of death in Canadian children aged 2-14 years only 75 years ago. The primary pathological lesion of diphtheria is the development of a thick leathery membrane consisting of bacteria, dead cells from the mucous membranes, and fibrin. This membrane surrounded by a narrow zone of inflammation, firmly adheres to the underlying tissues.