Diphtheria

Definition

Diphtheria is an acute infectious disease caused by the bacteria Corynebacterium diphtheriae.

Alternative Names

Causes, incidence, and risk factors

Diphtheria spreads through respiratory droplets (such as those produced by a cough or sneeze) of an infected person or someone who carries the bacteria but has no symptoms. Diphtheria can also be spread by contaminated objects or foods (such as contaminated milk).

The bacteria most commonly infects the nose and throat. The throat infection causes a gray to black, tough, fiber-like covering, which can block the airways. In some cases, diphtheria may first infect the skin, producing skin lesions.

Once infected, dangerous substances called toxins, produced by the bacteria, can spread through your bloodstream to other organs, such as the heart, and cause significant damage.

Because of widespread and routine childhood DPT immunizations, diphtheria is now rare in many parts of the world. There are fewer than five cases of diphtheria a year in the United States.

Risk factors include crowded environments, poor hygiene, and lack of immunization.

Symptoms

Symptoms usually occur 2 to 5 days after you have come in contact with the bacteria.

• Bluish coloration of the skin
• Bloody, watery drainage from nose
• Breathing problems
  • Difficulty breathing
  • Rapid breathing
  • Stridor
• Chills
• Croup-like (barking) cough
• Drooling (suggests airway blockage is about to occur)
• Fever
• Hoarseness
• Painful swallowing
• Skin lesions (usually seen in tropical areas)
• Sore throat (may range from mild to severe)

Note: There may be no symptoms.

Signs and tests

The health care provider will perform a physical exam and look inside your mouth. This may reveal a gray to black covering (pseudomembrane) in the throat, enlarged lymph glands, and swelling of the neck or larynx.

Tests used may include:

• Gram stain or throat culture to identify Corynebacterium diphtheriae
• Electrocardiogram (ECG)

Treatment

If the health care provider thinks you have diphtheria, treatment should be started immediately, even before test results are available.

Diphtheria antitoxin is given as a shot into a muscle or through an IV (intravenous line). The infection is then treated with antibiotics, such as penicillin and erythromycin.

People with diphtheria may need to stay in the hospital while the antitoxin is being received. Other treatments may include:

• Fluids by IV
• Oxygen
• Bed rest
• Heart monitoring
• Insertion of a breathing tube
• Correction of airway blockages

Anyone who has come into contact with the infected person should receive an immunization or booster shots against diphtheria. Protective immunity lasts only 10 years from the time of vaccination, so it is important for adults to get a booster of tetanus-diphtheria (Td) vaccine every 10 years.

Those without symptoms who carry diphtheria should be treated with antibiotics.

Support Groups

Expectations (prognosis)

Diphtheria may be mild or severe. Some people may not have symptoms. In others, the disease can slowly get worse.

The death rate is 10%. Recovery from the illness is slow.

Complications

The most common complication is inflammation of the heart muscle (myocarditis). The nervous system is also frequently and severely affected, which may result in temporary paralysis.

The diphtheria toxin can also damage the kidneys.

Calling your health care provider

Contact your health care provider if you have come in contact with a person who has diphtheria.

Remember that diphtheria is a rare disease. Diphtheria is also a reportable disease, and any cases are often publicized in the newspaper or on television. This helps you to know if diphtheria is present in your area.

Prevention

Routine childhood immunizations and adult boosters prevent the disease. See: Diphtheria immunization (vaccine)

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References

MacGregor RR. Corynebacterium diphtheriae. In: Mandell GL, Bennett JE, Dolan R, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 7th ed. Orlando, FL: Saunders Elsevier; 2009:chap 205.