131 - Corynebacteria

Summary

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 the skin; from here it gives rise to local and systemic signs or it can be asymptomatic. 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 and the peripheral nerves.

Cause

Diphtheria is distributed worldwide, with the highest incidence 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. There have been reports of diphtheria outbreaks in the newly independent states of the former Soviet Union. Diphtheria is seen in developed countries in people that return and travel to endemic areas as well as in immigrants from endemic areas.

The only significant reservoir of C. diphtheriae is the human host. The organism is transmitted directly from one person to another, and intimate contact is required. Transmission is usually by way of infected droplets of nasopharyngeal secretions. Infective skin exudate has been involved in human-to-human transmission. Transmission may also occur via animals, fomites, or milk. The infectious period is usually 2 weeks from onset of symptoms, as long as 6 weeks, and, if treated with antibiotics, to less than 4 days.