Corynebacterium diphtheriae (diphtheria)

Diphtheria is an acute, infectious, preventable, and sometimes fatal disease caused by Corynebacterium diphtheriae. The infection is usually localized to the upper part of the respiratory tract and/or the skin; from here it gives rise to local and systemic signs or it can be an asymptomatic carrier state. These signs are the result of a toxin produced by the microorganisms multiplying at the site of infection. The systemic complications particularly affect the heart (22%), the peripheral nerves (5%), and/or the kidneys (renal failure in severe cases).

Cause

Diphtheria is distributed worldwide, there are four biotypes: gravis, intermedius, mitis, and belfanti. All are associated with epidemic and endemic diphtheria. The highest incidence occurs in temperate climates. It occurs predominantly under poor socioeconomic conditions, where crowding is common and where many persons are either not immunized or inadequately immunized. In the United States 20% to 60% of adults are susceptible to diphtheria since the immunity wanes and it is not customary to receive boosters. In the 1990s there were reports of diphtheria outbreaks in the newly independent states of the former Soviet Union. Outbreaks were also experienced in other European countries and were characterized by a high fatality rate, and a large number of complications and adult cases. Diphtheria is seen in developed countries in people that travel to and return from endemic areas as well as in immigrants from endemic areas.