Diphtheria (dif-THEER-e-uh) is a serious bacterial infection usually affecting the mucous membranes of your nose and throat. Diphtheria typically causes a sore throat, fever, swollen glands and weakness. But the hallmark sign is a sheet of thick, gray material covering the back of your throat, which can block your airway, causing you to struggle for breath.
Diphtheria is extremely rare in the United States and other developed countries, thanks to widespread vaccination against the disease.
Medications are available to treat diphtheria. However, in advanced stages, diphtheria can damage your heart, kidneys and nervous system. Even with treatment, diphtheria can be deadly — up to 3 percent of people who get diphtheria die of it. The rate is higher for children under 15.
Diphtheria signs and symptoms usually begin two to five days after a person becomes infected and may include:
- A thick, gray membrane covering your throat and tonsils
- A sore throat and hoarseness
- Swollen glands (enlarged lymph nodes) in your neck
- Difficulty breathing or rapid breathing
- Nasal discharge
- Fever and chills
In some people, infection with diphtheria-causing bacteria causes only a mild illness — or no obvious signs and symptoms at all. Infected people who remain unaware of their illness are known as carriers of diphtheria, because they can spread the infection without being sick themselves.
Skin (cutaneous) diphtheria
A second type of diphtheria can affect the skin, causing the typical pain, redness and swelling associated with other bacterial skin infections. Ulcers covered by a gray membrane also may develop in cutaneous diphtheria.
Although it's more common in tropical climates, cutaneous diphtheria also occurs in the United States, particularly among people with poor hygiene who live in crowded conditions.
When to see a doctor
Call your family doctor immediately if you or your child has been exposed to someone with diphtheria. If you're not sure whether your child has been vaccinated against diphtheria, schedule an appointment. Make sure your own immunizations are current.
The bacterium Corynebacterium diphtheriae causes diphtheria. Usually C. diphtheriae multiplies on or near the surface of the mucous membranes of the throat. C. diphtheriae spreads via three routes:
- Airborne droplets. When an infected person's sneeze or cough releases a mist of contaminated droplets, people nearby may inhale C. diphtheriae. Diphtheria spreads efficiently this way, particularly in crowded conditions.
- Contaminated personal items. People occasionally catch diphtheria from handling an infected person's used tissues, drinking from the infected person's unwashed glass or coming into similarly close contact with other items on which bacteria-laden secretions may be deposited.
- Contaminated household items. In rare cases, diphtheria spreads on shared household items, such as towels or toys.
You can also come in contact with diphtheria-causing bacteria by touching an infected wound.
People who have been infected by the diphtheria bacteria and who haven't been treated can infect nonimmune people for up to six weeks — even if they don't show any symptoms.
People who are at increased risk of contracting diphtheria include:
- Children and adults who don't have up-to-date immunizations
- People living in crowded or unsanitary conditions
- Anyone who travels to an area where diphtheria is endemic
Diphtheria rarely occurs in the United States and Western Europe, where health officials have been vaccinating children against the condition for decades. However, diphtheria is still common in developing countries where immunization rates are low.
In areas where diphtheria vaccination is standard, the disease is mainly a threat to unvaccinated or inadequately vaccinated people who travel internationally or have contact with people from less-developed countries.
Left untreated, diphtheria can lead to:
- Breathing problems. Diphtheria-causing bacteria may produce a toxin. This toxin damages tissue in the immediate area of infection — usually, the nose and throat. At that site, the infection produces a tough, gray-colored membrane composed of dead cells, bacteria and other substances. This membrane can obstruct breathing.
- Heart damage. The diphtheria toxin may spread through your bloodstream and damage other tissues in your body, such as your heart muscle, causing such complications as inflammation of the heart muscle (myocarditis). Heart damage from myocarditis may be slight, showing up as minor abnormalities on an electrocardiogram, or severe, leading to congestive heart failure and sudden death.
- Nerve damage. The toxin can also cause nerve damage. Typical targets are nerves to the throat, where poor nerve conduction may cause difficulty swallowing. Nerves to the arms and legs also may become inflamed, causing muscle weakness. If C. diphtheria toxin damages the nerves that help control muscles used in breathing, these muscles may become paralyzed. Respiration may then become impossible without a respirator or another device to assist with breathing.
With treatment, most people with diphtheria survive these complications, but recovery is often slow. Diphtheria is fatal in as many as 3 percent of those who get the disease.
Before antibiotics were available, diphtheria was a common illness in young children. Today, the disease is not only treatable but is also preventable with a vaccine.
The diphtheria vaccine is usually combined with vaccines for tetanus and whooping cough (pertussis). The three-in-one vaccine is known as the diphtheria, tetanus and pertussis vaccine. The latest version of this vaccine is known as the DTaP vaccine for children and the Tdap vaccine for adolescents and adults.
The diphtheria, tetanus and pertussis vaccine is one of the childhood immunizations that doctors in the United States recommend during infancy. Vaccination consists of a series of five shots, typically administered in the arm or thigh, given to children at these ages:
- 2 months
- 4 months
- 6 months
- 15 to 18 months
- 4 to 6 years
The diphtheria vaccine is effective at preventing diphtheria. But there may be some side effects. Some children may experience a mild fever, fussiness, drowsiness or tenderness at the injection site after a DTaP shot. Ask your doctor what you can do for your child to minimize or relieve these effects.
Rarely, the DTaP vaccine causes serious complications in a child, such as an allergic reaction (hives or a rash develops within minutes of the injection), seizures or shock — complications that are treatable.
Some children — such as those with epilepsy or another nervous system condition — may not be candidates for the DTaP vaccine.
After the initial series of immunizations in childhood, you need booster shots of the diphtheria vaccine to help you maintain immunity. That's because immunity to diphtheria fades with time.
Children who received all of the recommended immunizations before age 7 should receive their first booster shot at around age 11 or 12. The next booster shot is recommended 10 years later, then repeated at 10-year intervals. Booster shots are particularly important if you travel to an area where diphtheria is common.
The diphtheria booster is combined with the tetanus booster — the tetanus-diphtheria (Td) vaccine. This combination vaccine is given by injection, usually into the arm or thigh.
Tdap is a combined tetanus, diphtheria and acellular pertussis (whooping cough) vaccine. It's a one-time alternative vaccine for adolescents age 11 through 18 and adults who haven't previously had a Tdap booster. It's also recommended for anyone who's pregnant, regardless of previous vaccination status.
Talk to your doctor about vaccines and booster shots if you're unsure of your vaccination status. Tdap may also be recommended as part of the Td series for children ages 7 through 10 who aren't up to date with the vaccine schedule.