Diphtheria

Diphtheria (dif-THEER-e-uh) is an infection of the lining of the upper respiratory tract (the nose and throat). It is a serious disease that can cause breathing difficulty and other complications, including death. Routine vaccination against diphtheria has made it rare in the United States.

What Is Diphtheria?

Diphtheria is an infection caused by a bacterium called Corynebacterium diphtheriae (kor-ih-nee-bak-TEER-e-um dif-THEER-e-eye) that infects the upper respiratory tract. As the bacteria infect the nose, throat, or larynx (LAIR-inks, the voicebox), a distinctive thick membrane forms over the site of infection. The membrane can become large enough to interfere with a person's breathing and swallowing. Some strains of Corynebacterium diphtheriae also produce an exotoxin ^* that can cause arthritis and damage to the nerves and heart. Sepsis, a potentially serious spreading of infection (usually bacterial) through the bloodstream and body, can result from diphtheria, causing shock ^* , heart failure, and even death.

How Common Is Diphtheria?

Diphtheria infection occurs throughout the world and is common in developing regions of Africa, Asia, and South America where children often do not receive the diphtheria vaccine. Cases usually occur in winter and the cooler months of autumn and spring.

Diphtheria infection is extremely rare in the United States because of the widespread use of routine diphtheria vaccination during childhood. From 1980 through 2000, 51 cases of diphtheria were reported in the United States. However, a diphtheria epidemic ^* has affected the countries that make up the former Soviet Union; since 1990 more than 150,000 cases have been reported.

Is Diphtheria Contagious?

Diphtheria is highly contagious. An untreated person who has diphtheria can spread the infection for up to a month. Within 48 hours of receiving antibiotics, however, people infected with diphtheria are usually no longer contagious.

The bacteria that cause diphtheria are spread through the air in drops of moisture from the respiratory tract, often from coughing or sneezing. Sharing drinking glasses or eating utensils or handling soiled tissues or handkerchiefs that have been used by a person with the disease can also transmit the bacteria. A person can get diphtheria from someone who has symptoms of the disease or from someone who is just a carrier ^* of the bacteria.

What Are the Signs and Symptoms of Diphtheria?

Within 5 days after becoming infected, a person typically begins to have symptoms of diphtheria. Early symptoms often include a severe sore throat, runny nose, mild fever, and swollen glands in the neck. People infected with diphtheria in the nose, throat, or larynx usually develop a thick membrane at the site of the infection. Membranes in the nose are often white, whereas those at the back of the throat are gray-green.

As diphtheria progresses, respiratory symptoms can become more severe and include difficulty breathing or swallowing and a bark-like cough. Sometimes inflammation and swelling in the throat and the diphtheria membrane itself can cause blockage of the upper airways, making emergency treatment necessary.

How Is Diphtheria Diagnosed and Treated?

Diphtheria is diagnosed when the membrane that signals the disease is seen in the nose or throat during an examination of someone with symptoms of the disease. The diagnosis is confirmed by taking a swab of the coating from underneath the membrane and performing a laboratory test that identifies diphtheria bacteria.

Hospitalized people who are known to have diphtheria are kept isolated to prevent the disease from spreading to others. Patients are treated in the hospital with antibiotics and diphtheria antitoxin ^* . The antitoxin, which is produced in horses, is given intravenously (directly into a vein).

In severe cases of diphtheria, patients may need a ventilator (VEN-tuh-lay-ter) to help with breathing or medication to treat complications of the disease, such as septic shock ^* , heart inflammation, or heart failure. After they leave the hospital, bed rest at home for several weeks is generally recommended. Members of the same household are usually given a diphtheria booster vaccine to protect against possible infection. Recovery from diphtheria often takes 4 to 6 weeks or more.

Complications of diphtheria include abnormal heart rhythms, arthritis, and neuritis ^* . Diphtheria is most dangerous for children under 5 and adults over 40. Death occurs in up to 10 percent of people with diphtheria who receive medical treatment; death rates are higher in some parts of the world where treatment is not readily available.

Can Diphtheria Be Prevented?

In the United States, immunization programs have been very effective in preventing diphtheria. The diphtheria vaccine is given in combination with vaccines for tetanus ^* and pertussis ^* (this is called the DTaP vaccine) as part of a child's routine immunizations. Four doses of the vaccine are given before 2 years of age. A first booster dose is given at 4 to 6 years of age when a child enters school. Additional booster doses are recommended every 10 years, in combination with a tetanus booster.

Sometimes people have mild reactions to the vaccine, including a low-grade fever, tenderness at the injection site, and irritability. Very rarely, stronger reactions such as seizures ^* or allergic reactions can occur.