Comment:

Diphtheria, caused by the bacterium Corynebacterium diphtheriae, is a devastating disease that is entirely preventable by childhood immunisation. In Western nations, diphtheria had been largely eradicated by immunisation programs, but as the immunisation rate has dropped, the disease has risen in incidence. The bacterium produces a toxin that injures the lining cells of the throat, tonsils, vocal cords and trachea, resulting in swelling, inflammation and the formation of a tenacious "pseudomembrane" that can obstruct the airway. The toxin can also be absorbed into the bloodstream, where it may affect the heart, causing an abnormal rhythm or heart failure. Peripheral nerves may also be affected, causing difficulty in swallowing or paralysis of the respiratory muscles.