Definition of Diphtheria

Diphtheria: An acute infectious disease that typically strikes the upper respiratory tract including the throat. It is caused by infection with the bacteria Corynebacterium diphtheriae. Symptoms include sore throat and mild fever at first. As the disease progresses, a membranous substance forms in the throat that makes it difficult to breathe and swallow.

Diphtheria can be deadly. It is one of the diseases that the DTP (Diphtheria-Tetanus-Pertussis) and DTaP (Diphtheria-Tetanus-acellular Pertussis) vaccines are designed to prevent.