Diphtheria is a potentially fatal, contagious disease that usually involves the nose, throat, and air passages, but may also infect the skin. Its most striking feature is the formation of a grayish membrane covering the tonsils and upper part of the throat.

Like many other upper respiratory diseases, diphtheria is most likely to occur during winter months. At one time it was a major cause of childhood death, but it is now rare in developed countries because of widespread immunization.

People who have not been immunized may get diphtheria at any age. The disease is spread most often by the coughing or sneezing of an infected person or carrier. It is vital to seek medical help at once when diphtheria is suspected.

The symptoms of diphtheria are caused by toxins produced by the diphtheria bacillus, Corynebacterium diphtheriae. These toxins destroy healthy tissue in the throat around the tonsils...