Diphtheria is a highly contagious bacterial infection that is spread between humans and causes an infection of the upper respiratory tract, which can lead to breathing difficulties and asphyxiation. Diphtheria has caused devastating epidemics throughout the world throughout history, and at the end of the 7th century, the disease was still the leading cause of infant mortality in France. It is no longer endemic in industrialized countries where the extremely rare cases observed are imported. However, the disease is still a health problem in parts of the world where childhood immunization is not routine. More than 000 cases were reported to WHO globally in 2014. (1)

A distinction is made between respiratory diphtheria and cutaneous diphtheria.

After an incubation period of two to five days, the disease manifests itself as sore throat: irritation of the throat, fever, swelling of the glands in the neck. The disease is recognized by the formation of whitish or grayish membranes in the throat and sometimes the nose, causing difficulty in swallowing and breathing (in Greek, “diphtheria” means “membrane”).

In the case of cutaneous diphtheria, mainly in tropical areas, these membranes are found at the level of a wound.

Diphtheria is caused by bacteria, Corynebacterium diphtheriae, which attacks the tissues of the throat. It produces a toxin that causes the accumulation of dead tissue (false membranes) which can go as far as obstructing the airways. This toxin can also spread in the blood and cause damage to the heart, kidneys and nervous system.

Two other species of bacteria are able to produce diphtheria toxin and therefore cause disease: Corynebacterium ulcerans et Corynebacterium pseudotuberculosis.

Respiratory diphtheria is spread from person to person through droplets that are projected during coughing and sneezing. The bacteria then enter through the nose and mouth. Cutaneous diphtheria, which is seen in some tropical regions, is spread through direct contact with a wound.

It should be noted that, unlike Corynebacterium diphtheriae which is transmitted from human to human, the other two bacteria responsible for diphtheria are transmitted from animals to humans (these are zoonoses):

• Corynebacterium ulcerans is transmitted by ingestion of raw milk or by contact with cattle and pets.
• Corynebacterium pseudotuberculosis, the rarest, is transmitted by contact with goats.

In our latitudes, it is in winter that diphtheria is most frequent, but in tropical areas it is observed throughout the year. Epidemic outbreaks more easily affect densely populated areas.

The vaccine

Vaccination for children is compulsory. The World Health Organization recommends that the vaccine be given in combination with those for tetanus and pertussis (DCT), at 6, 10 and 14 weeks, followed by booster shots every 10 years. Vaccination prevents 2 to 3 million deaths from diphtheria, tetanus, pertussis and measles each year worldwide, according to WHO estimates. (2)

The treatment

The treatment consists of administering an anti-diphtheria serum as quickly as possible to stop the action of the toxins produced by the bacteria. It is accompanied by antibiotic treatment to kill the bacteria. The patient can be placed in respiratory isolation for a few days in order to avoid contagion with the people around him. About 10% of people with diphtheria die, even with treatment, the WHO warns.