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Diphtheria   

Overview | Symptoms | Treatment | Prevention

Definition:

An acute infectious disease caused by the toxin-producing bacteria Corynebacterium diphtheriae. It usually affects the respiratory tract (primarily the larynx, tonsils, and throat). But it can also affect the skin, and the toxin produced by this bacteria can damage the nerves and heart.

Causes and Risks

Diphtheria is found only in humans and is usually transmitted by respiratory droplets from infected persons or asymptomatic carriers, but can be transmitted by contaminated objects or foods (such as contaminated milk). The incubation period is 2 to 5 days.

The bacteria primarily infect the nose and throat although they may initially infect the skin producing skin lesions. C. diphtheriae produces a toxin which causes tissue damage (necrosis) in the immediate area of the infection, usually the nose and throat. It can spread via the bloodstream to other organs where it can cause significant damage. Although the toxin can damage any tissue, that of heart and nerves are most frequently and most severely affected.

The localized infection in the throat and tonsillar area produces a characteristic membrane which is gray to black in color, tough, and fibrous. This membrane can cause airway obstruction.

The disease may be mild and go unrecognized, or it may become progressive. If toxin enters the bloodstream the patient may develop inflammation of the heart muscle (myocarditis) which is the most commonly seen and most worrisome complication. Toxic effects on the nervous system may cause temporary paralysis.

The disease is now rare in many parts of the world because of widespread immunization. Risk factors are crowding, poor hygiene, and lack of immunization. Only 5 cases of diphtheria were reported in the U.S. in 1991. In 1993 and 1994 the separated states of the former USSR experienced a diphtheria epidemic with over 150,000 reported cases and 5,000 deaths. The epidemic was related to a drop in routine childhood immunizations (DPT) to less than 60% compliance, failure to give booster doses to adults, and worsening economic conditions in the affected countries.

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