Diphtheria: Symptoms, Causes and Prevention

Diphtheria is an infectious disease of the nose and throat that is common among young children. Diphtheria symptoms can lead to life-threatening complications, even death, in children who are not immunised.


What is Diphtheria?

Diphtheria is a contagious disease spread through physical contact or droplets during coughing and sneezing. Occasionally, diphtheria may be transmitted from skin sores. It may also spread through someone who carries the bacteria but shows no symptoms. Although serious and highly contagious, there is a vaccine for the disease, which should be administered for diphtheria prevention.

Diphtheria Causes and Risk Factors

Diphtheria is caused by a bacteria called Corynebacterium diphtheriae (pictured below). This disease mainly affects the mucous membranes of the upper airway passage and occasionally affects the skin.

Risk factors for the spread of diphtheria include:
​Overcrowded areas
Poor hygiene
Lack of immunisation

Diphtheria Symptoms and Signs

Diphtheria bacteria usually live in the nose and the throat of an infected person. Some infected individuals may become carriers of the bacteria without displaying any symptoms.

Diphtheria symptoms usually appear within two to four days of the infection and may include:
Sore throat, hoarseness
Low-grade fever and general body weakness
Difficulty in swallowing and breathing (due to a thick membrane that forms in the nose and throat)
Neck swelling (due to enlarged lymph glands in severe cases)

Only toxin-producing strains of the bacteria can cause severe disease by spreading the toxin in the bloodstream of the infected person. These bacteria strains may infect the skin and produce skin sores.

Diphtheria Complications

In more serious cases, the respiratory infection may spread beyond the throat due to the release of toxin by the bacteria. The diphtheria toxin may spread through the bloodstream to other parts of the body, such as the heart and the nerves. 

Possible complications include:
Damage to the heart muscles often leading to heart failure (myocarditis)
Damage to the peripheral nerves (neuropathy), resulting in muscle weakness, and in severe cases, eventually leading to paralysis
Temporary paralysis of the breathing muscles occasionally
Serious breathing problems including suffocation as the membrane coating at the back of the throat moves deeper into the breathing passage

Diphtheria is a serious disease and may be fatal despite proper treatment in some cases. Complications are less frequent when the infection is limited to the skin.

Diphtheria Screening and Diagnosis

A detailed physical examination helps in diagnosis and a throat culture sample usually confirms the diagnosis. Early diagnosis and treatment can help to prevent life-threatening complications.

​Diphtheria Treatment

An infected person needs to be hospitalised and treated with both diphtheria antitoxin and antibiotics immediately. Diphtheria antitoxin is given as an injection to neutralise the circulating toxins in the body and to prevent the disease from worsening. 

The infection is then treated with appropriate antibiotics. Some patients with difficulty in breathing due to a block in the airway may need to be ventilated.

Anyone in close contact with the infected person should have their throat cultures tested. They should also receive antibiotics immediately to prevent its transmission to others, in addition to making sure that they have been adequately immunised.

A patient usually becomes non-infectious within 48 hours after starting on antibiotics. Those without symptoms should also be treated with antibiotics if they are carriers of the bacteria. Untreated patients remain infectious for around two to three weeks.

Diphtheria Prevention

Immunisation is the best form of prevention. Routine childhood immunisation and adult booster doses also help to prevent the disease throughout one’s lifetime.
The diphtheria vaccine which is usually given in a combination with pertussis and tetanus vaccines, is known as the DTaP vaccine.
In Singapore, vaccination with DTaP/ Tdap is compulsory by law and recommended under the National Childhood Immunisation Schedule.
A total of five shots are administered starting at the age of three months. Subsequent doses are given at the ages of four and five months. The first booster dose is given at 18 months, followed by a top-up booster above the age of 11 years to maintain continued protection against diphtheria.
Booster doses of diphtheria should be given every 10 years after recommended immunisation for continued prevention against diphtheria.
Booster doses are particularly recommended for those traveling to areas where the disease may still be present.
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Diphtheria: Symptoms, Causes and Prevention

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