Diphtheria is a serious communicable bacterial disease that causes severe inflammation of the nose, throat and windpipe (trachea). It is caused by the bacterium, Corynebacterium diphtheriae. The bacteria produce toxins that cause an abnormal membrane to grow in the throat, which can lead to suffocation. Other dangerous complications include paralysis and heart failure if the toxins spread throughout the body. Around 10 per cent of people exposed to diphtheria die from the disease.