Diphtheria is a very contagious and potentially life-threatening infection that usually attacks the throat and nose. In more serious cases, it can attack the nerves and heart. Because of widespread immunization, diphtheria is very rare in the United States. However, some people are not adequately vaccinated, and cases still occur. Diphtheria is caused by Corynebacterium diphtheriae, a bacterium.
Diphtheria is common in many parts of the world.
Diphtheria bacteria live in the mouth, nose, throat, or skin of infected persons. Diphtheria spreads from person to person very easily. People get diphtheria by breathing in diphtheria bacteria after an infected person has coughed or sneezed. People also get diphtheria from close contact with discharges from an infected person's mouth, nose, throat, or skin. Usually, diphtheria develops in the throat.