Factsheet about diphtheria


Diphtheria is an acute disease caused by toxin-producing strains of Corynebacterium diphtheriae (in some cases also by Corynebacterium ulcerans) bacteria, that is known to colonise mucous membranes. Following infection, after a usually short incubation period (2–5 days), the release of the cytotoxin may produce characteristic lesions on the affected mucous membranes (tonsils, pharynx, larynx, nose) or wounds. Obstruction of the airway may follow. The toxin, once absorbed, reaches other organs and can cause myocarditis, paralytic symptoms and nephritis. In non-vaccinated individuals, and especially if proper treatment is delayed, death can occur in up to 10% of clinical cases despite antibiotics and the use of anti-sera, Diphtheria is transmitted mainly by direct projection (droplet spread). It is preventable by vaccination.


Diphtheria is a disease caused by bacteria Corynebacterium diphtheriae and Corynebacterium ulcerans. It can cause respiratory symptoms or non-respiratory forms that affect other parts of the body, including the skin.


People infected with diphtheria bacteria may develop symptoms or may have no symptoms but be carrying the bacteria and able to infect others. The majority of people with diphtheria will have a respiratory tract infection, with a sore throat and low grade fever in the first few days of the illness. Mild cases of the illness will not develop further symptoms. However, if the disease is more severe, a dense membrane will develop which could be local—for example, just on the tonsils or pharynx—or could cover a wide area of the patient’s respiratory tract. More severe cases can develop a swollen “bull’s neck” appearance. In tropical regions, diphtheria can cause cutaneous symptoms affecting the skin. Lesions appear on the skin that form ulcers covered in a grey membrane that do not heal.


Diphtheria can cause toxins to be released into the circulatory system and tissues that can cause extensive organ damage. Complications affecting the heart and neurological complications, such as paralysis, can develop. The most common cause of death is suffocation by aspiration of the membrane.

Ways to catch diphtheria

Diphtheria is caught by coming into contact with droplets from the respiratory tract of an infected person—particularly spread by coughing or sneezing. If the disease is cutaneous, it can be spread by coming into contact with the wounds or lesions of an infected person. People who have untreated diphtheria can be infectious for up to four weeks and people carrying the bacteria could be infectious for longer. Travel, close contact with cattle, and eating raw dairy products are all potential risk factors for infection.

People most at risk

Diphtheria is very rare in most European countries. The cutaneous form of the disease is seen mostly in tropical regions and often in poor inner city inhabitants and alcoholics. People who have been in close contact with someone infected with diphtheria should be tested for the disease and kept under surveillance for seven days to see whether they show signs and symptoms. Those living in the same household as someone with diphtheria may be given a preventative course of antibiotics. Diagnosis Diphtheria can be confirmed by laboratory tests on swabs taken from a patient’s throat and nose and blood tests.


Diphtheria can be treated with antitoxin and antibiotics.

How to avoid getting diphtheria

An effective vaccine is available against diphtheria and mass immunisation has led to the reduction in the number of cases in Europe.

Note: The information contained in this factsheet is intended for the purpose of general information and should not be used as a substitute for the individual expertise and judgement of healthcare professionals.