Diphtheria is an acute infection caused by the bacteria Corynebacterium diphtheriae.
Causes, incidence, and risk factors
Diphtheria spreads through respiratory droplets (such as from a cough or sneeze) of an infected person or someone who carries the bacteria but has no symptoms.
The bacteria most commonly infects your nose and throat. The throat infection causes a gray to black, tough, fiber-like covering, which can block your airways. In some cases, diphtheria infects your skin first and causes skin lesions.
Once infected, the bacteria make dangerous substances called toxins. The toxins spread through your bloodstream to other organs, such as the heart and brain, and cause damage.
Because of widespread immunization (vaccination) of children, diphtheria is now rare in many parts of the world.
Risk factors for diphtheria include crowded environments, poor hygiene, and lack of immunization.
Symptoms usually occur 1 to 7 days after the bacteria enter your body:
- Bluish coloration of the skin
- Bloody, watery drainage from nose
- Breathing problems, including difficulty breathing, fast breathing, high-pitch breathing sound (stridor)
- Croup-like (barking) cough
- Drooling (suggests airway blockage is about to occur)
- 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 the diphtheria bacteria
- Toxin assay (to detect the presence of the toxin made by the bacteria)
- Electrocardiogram (ECG)
If the health care provider thinks you have diphtheria, treatment will likely be started right away, even before test results come back.
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.
You may need to stay in the hospital while getting the antitoxin is being received. Other treatments may include:
- Fluids by IV
- Bed rest
- Heart monitoring
- Insertion of a breathing tube
- Correction of airway blockages
Persons without symptoms who carry diphtheria should be treated with antibiotics.
Diphtheria may be mild or severe. Some people may not have symptoms. In others, the disease can slowly get worse. Recovery from the illness is slow.
People may die, especially when the disease affects the heart.
The diphtheria toxin can also damage the kidneys.
Calling your health care provider
Contact your health care provider right away if you have come in contact with a person who has diphtheria.
Diphtheria is a rare disease. It 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.
If you have been in close contact with a person who has diphtheria, contact your health care provider right away. Ask whether you need antibiotics to prevent getting diphtheria.
Routine childhood immunizations and adult boosters prevent the disease.
Anyone who has come into contact with an infected person should get an immunization or booster shot against diphtheria, if they have not already received it. Protection from the vaccine lasts only 10 years. So it is important for adults to get a booster vaccine every 10 years. The booster is called tetanus-diphtheria (Td). (The shot also has vaccine medicine for an infection called tetanus.)
Centers for Disease Control and Prevention. Advisory Committee on Immunization Practices (ACIP) Recommended Immunization Schedules for Persons Aged 0 Through 18 Years and Adults Aged 19 Years and Older — United States, 2013. MMWR. 2013;62(Suppl 1):1-19.
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. Philadelphia, PA: Elsevier Saunders; 2009:chap 205.
Sutter R. Diphtheria and other corynebacteria infections. In: Goldman’s Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 300.
Last reviewed 1/29/2013 by Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.
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