Diphtheria is a contagious, sometimes fatal infection of the upper respiratory tract caused by the bacterium Corynebacterium diphtheriae.
Years ago, diphtheria was one of the leading causes of death among children. Today, diphtheria is rare in developed countries, primarily because of widespread vaccination. Fewer than five cases occur in the United States each year, but diphtheria bacteria still exist in the world and can cause outbreaks if vaccination is inadequate.
The bacteria that cause diphtheria are usually spread in droplets of moisture coughed into the air. Usually the bacteria multiply on or near the surface of the mucous membranes of the mouth or throat, where they cause inflammation. Some types of Corynebacterium diphtheriae release a potent toxin, which can damage the heart, kidneys, and nervous system. A milder form of diphtheria affects only the skin and occurs mainly in adults. This form is more common among people with poor hygiene (for example, homeless people).
Symptoms and Diagnosis
The illness begins 1 to 4 days after exposure to the bacteria. Symptoms begin over a few days, with sore throat, a general feeling of illness (malaise), and a fever up to 103° F (39.4° C). The child also may have a fast heart rate, nausea, vomiting, chills, and a headache. The lymph nodes in the neck may swell. The inflammation may make the throat swell, narrowing the airway and making breathing extremely difficult.
Typically, the bacteria form a tough, gray pseudomembrane—a sheet of material composed of dead white blood cells, bacteria, and other substances—near the tonsils or other parts of the throat. The pseudomembrane narrows the airway and may suddenly become detached and block the airway completely, preventing the child from being able to breathe. The toxin produced by diphtheria bacteria usually affects certain nerves, particularly those to the muscles of the face, throat, arms, and legs, causing symptoms such as difficulty swallowing or moving the eyes, arms, or legs. The bacterial toxin may also cause inflammation of the heart muscle (myocarditis), sometimes leading to abnormal heart rhythms, heart failure, and death.
A doctor suspects diphtheria in a sick child who has a sore throat with a pseudomembrane, particularly if muscles of the face or throat are paralyzed and if the child was not vaccinated. The diagnosis is confirmed by culture of material from the child's throat.
Prevention and Treatment
Children are routinely immunized against diphtheria (see see Vaccinating Infants and Children). The diphtheria vaccine is usually combined with vaccines for tetanus and pertussis (whooping cough).
A child with symptoms of diphtheria is typically hospitalized in an intensive care unit and given antibodies (antitoxins) to neutralize the diphtheria toxin. Doctors also give antibiotics, such as penicillin or erythromycin, to kill the diphtheria bacteria. Antibiotics are given for 14 days. The child must be kept in isolation (to prevent other people from being exposed to infected secretions) until two cultures, taken after the antibiotics are stopped, confirm that the bacteria have been killed.
Last full review/revision June 2006 by Geoffrey A. Weinberg, MD