What is diphtheria?

Diphtheria is an acute respiratory disease caused by the bacterium Corynebacterium diphtheriae. The symptoms of the disease are primarily the result of a powerful toxin produced by the bacteria.

The disease usually occurs as membranous nasopharyngitis or obstructive laryngotracheitis and may cause serious complications.

In the cold and temperate climates of Europe and North America, diphtheria is best known as an illness of the nose and throat. Like common cold and the flu, this form of diphtheria is what doctors call an upper respiratory infection.

Corynebacterium diphtheriae is an irregular staining, gram-positive, nonspore-forming, nonmotile pleomorphic bacillus with 4 colony types, i.e mitis, intermedius, bellanti and gravis. Strains of C. diphtheriae may be toxogenic or nontoxigenic.

Immunity to diphtheria can develop either from natural exposure to the organism or from vaccination. In either case, repeated exposures to the organism (or the material in the vaccine) are required to develop and maintain immunity.

The most common symptoms of diphtheria are sore throat, a low-grade fever and the appearance of a ‘false membrane’ – a slimy, leathery barrier - the victim’s throat.
What is diphtheria?