By dr. Alex Turnip

What is diphtheria?

Diphtheria is an infection caused by the bacterium Corynebacterium diphtheriae. Signs and symptoms usually start 2 – 5 days after exposure and range from mild to severe. Symptoms often come on gradually, beginning with a sore throat and fever. In severe cases, the bacteria produces a poison (toxin) that causes a thick grey or white patch at the back of throat. This can block the airway making it hard to breathe or swallow and also create a barking cough. The neck may swell in part due to enlarged lymph nodes.

The poison may also get into the blood stream causing complications that may include inflammation and damage of the heart muscle, inflammation of nerves, kidney problems, and bleeding problems due to low blood platelets. The damaged heart muscles may result in an abnormal heart rate and inflammation of the nerves may result in paralysis.

What are the symptoms and signs of diphtheria?

Initially the symptoms of diphtheria may be similar to a viral upper respiratory infection but symptoms worsen over about two to five days. The symptoms may include: 

As the disease progresses, an adherent membrane (pseudomembrane) may begin to cover the tonsils, pharynx, and/or nasal tissues. If untreated, the pseudomembrane can extend into the larynx and trachea and obstruct the airway; this can lead to death.

Cutaneous diphtheria symptoms include initial reddish lesions that are painful and that may develop into nonhealing ulcers. Some ulcers may be covered by a gray-colored membrane.

How is diphtheria spread?

Diphtheria is an infection spread only among humans. It is contagious by direct physical contact with:

  • droplets breathed out into the air
  • secretions from the nose and throat, such as mucus and saliva
  • infected skin lesions
  • objects, such as bedding or clothes an infected person has used, in rare cases

The infection can spread from an infected patient to any mucous membrane in a new person, but the toxic infection most often attacks the lining of the nose and throat.

Diagnosis and Treatment

Doctors usually decide if a person has diphtheria by looking for common signs and symptoms. They can use a swab from the back of the throat and test it for the bacteria that cause diphtheria. A doctor can also take a sample from a skin lesion (like a sore) and try and grow the bacteria to be sure a patient has diphtheria.

It is important to start treatment right away if a doctor suspects diphtheria and not to wait for laboratory confirmation. In the United States, before there was treatment for diphtheria, up to half of the people who got the disease died from it.

Diphtheria treatment today involves:

  • Using diphtheria antitoxin to stop the poison (toxin) produced by the bacteria from damaging the body
  • Using medicines (called antibiotics) to kill and get rid of the bacteria

Diphtheria patients are usually kept in isolation, until they are no longer contagious — this usually takes about 48 hours after starting antibiotics. After the patient finishes taking the antibiotic, the doctor will run tests to make sure the bacteria are not in the patient’s body anymore.

How is diphtheria prevented?

Diphtheria is preventable with the use of antibiotics and vaccines.

The vaccine for diphtheria is called DTaP. It’s usually given in a single shot along with vaccines for pertussis and tetanus. The DTaP vaccine is administered in a series of five shots. It’s given to children at the following ages:

  • 2 months
  • 4 months
  • 6 months
  • 15 to 18 months
  • 4 to 6 years

In rare cases, a child might have an allergic reaction to the vaccine. This can result in seizures or hives, which will later go away.

Vaccines only last for 10 years, so your child will need to be vaccinated again around age 12. For adults, it’s recommended that you get a combined diphtheria-tetanus-pertussis booster shot once. Every 10 years afterward, you’ll receive the tetanus-diphtheria (Td) vaccine. Taking these steps can help prevent you or your child from getting diphtheria in the future.