Diphtheria Facts Diphtheria Diphtheria is a very contagious and potentially life-threatening bacterial disease.
Diphtheria usually attacks the throat and nose.
In more serious cases, it can attack the heart and nerves. Because of widespread immunization, diphtheria is very rare in the United States. Diphtheria is re-emerging in some areas of the world where immunization practices are lax. Routine vaccination of both children and adults is essential to prevent the re-emergence of diphtheria in the United States. Diphtheria is a very contagious and potentially life-threatening infection that usually attacks the throat and nose.