Diphtheria is a disease, caused by a bacteria.
It has a sudden onset and attacks the tonsils, throat or nasal passage and interferes with breathing. The bacteria produces a poison which can damage the heart, kidney, and nerves. Occasionally, the bacteria infects and inflames the skin. Unimmunized children under 15 years of age are most likely to contract diphtheria. The disease is also found among adults whose immunization was neglected and is most severe in unimmunized or inadequately immunized individuals.