Acute infectious Corynebacterium diphtheriae .
The bacterium usually enters through the tonsils, nose, or throat and multiplies there, forming a thick membrane that adheres to the tissues and sometimes blocks the trachea, requiring emergency treatment.The bacteria produce a {{link=toxin">toxin that spreads to cause other symptoms, including fever, chills, sore throat, and lesions in heart muscle and peripheral nerve tissue that may cause death from heart failure and paralysis. Diphtheria is treated with an antitoxin that neutralizes the toxin and produces long-term immunity . Vaccination has greatly reduced its occurrence in Europe and North America.