Gesundheit für Mensch, Tier & Pflanze

Diphtheria

Corynebacterium diphtheriae

Profile

Classical diphtheria is a severe infectious disease that can be fatal without adequate therapy. It is caused by certain toxin-producing bacteria, Corynebacterium diphtheriae.

Occurrence

In Western countries, usually only sporadic cases are registered. In many regions of the world, however, diphtheria is still endemic, such as the Far and Middle East, South America or Africa.

Pathogen reservoir

Human

Infection route

Transmission occurs mainly via the air (aerogenic) in the form of droplets or through direct contact with respiratory secretions or wound exudates. Vomit or contaminated food (raw milk) or objects can also play a role in transmission.

Incubation time

Two to five days

Symptoms

The classic ports of entry for Corynebacterium diphtheriae are the respiratory tract and the skin. Cutaneous d iphtheria occurs mainly in tropical regions and manifests as poorly healing ulcers (skin ulcers) covered with dirty grey membranes. Respiratory diphtheria begins with sore throat, fatigue, and swelling of the lymph nodes. Pseudomembranes (Greek: "diphthera", dermis) form in the nasopharynx, extend over one or both palatine tonsils and over the remaining tissues of the soft palate, and bleed profusely when removed. The color of these membranes may be white, dirty gray, green, or black. These pseudomembranes can also affect the larynx, trachea, and bronchi, causing respiratory distress that can become life-threatening without immediate action (intubation).

Therapy

Therapy must be initiated as early as possible (at preliminary clinical diagnosis). It is carried out simultaneously with antibiotics and diphtheria antitoxin (diphtheria serum). With complete basic immunization and regular boosters, the course of the disease is usually mild.

Prevention

Prevention should begin in childhood. This consists of active immunization with a "toxoid vaccine", an inactivated diphtheria toxin. The vaccine for children is available as a combination vaccine with tetanus and pertussis and poliomyelitis. The immunization should be refreshed every ten years after the basic immunization (e.g. in combination with tetanus).

Situation in Austria

In 2021, five samples, four of which were of human origin, were tested at the National Reference Center for Diphtheria - Laboratory. Corynebacterium diphtheriae was detected in four samples.

Positiv bestätigte Proben in Österreich

Technical information

Classical diphtheria is a notifiable disease.

Corynebacteria are gram-positive, facultatively anaerobic, non-spore-forming, irregularly shaped (club-shaped) rod-shaped bacteria (Greek "coryne"). Most representatives of this group are opportunistic germs (i.e. only "pathogenic" under special conditions). Corynebacterium diphtheriae, the causative agent of diphtheria, is of greatest clinical importance, although only toxin-producing strains can cause diphtheria.

In addition to C. diphtheriae, C. ulcerans and C. pseudotuberculosis can also be the cause of diphtheria. Based on morphological and biochemical characteristics, C. diphtheriae is divided into three biotypes: gravis, intermedius, and mitis.

Symptomatology

Cutaneous diphtheria occurs mainly in tropical regions and manifests as poorly healing skin ulcers covered with dirty gray membranes.

Respiratory diphtheria begins after an incubation period of two to five days with sore throat, fatigue, cervical lymph node swelling, and subfebrile temperatures. Adherent pseudomembranes (Greek: "diphthera", dermis) form in the nasopharynx, extend over one or both palatine tonsils and over the remaining tissues of the soft palate, and bleed profusely when cleared. The color of these membranes may be white, dirty gray, green, or black.

These pseudomembranes may also affect the larynx, trachea, and bronchi and cause severe symptoms, such as hoarseness, dyspnea, or cyanosis, which can become life-threatening without immediate action (intubation). As a result of the toxin formation, conduction disorders occur predominantly in the heart and the central nervous system. These manifest themselves as cardiac arrhythmias, conduction disorders of varying degrees as well as acute cardiac insufficiency with circulatory collapse. Primarily, the motor nerves are damaged. Occasionally, sensory nerves are also affected, manifesting as "glove stocking" neuropathy.

Diagnostic

The method of choice is the cultivation of the pathogen from clinical examination material. Smears from inflamed sites (nose, throat, palatine tonsils, wound) as well as from ablated membranes are most suitable.

If wound swabs cannot be obtained, it is recommended that aspirates be obtained from the wound margin. In addition, depending on clinical suspicion, other materials (blood, urine) can be used after consultation with the laboratory. After culturing, the detection of toxin production is of great importance for confirming the diagnosis.

Submissions should always include information on the origin of the isolates as well as the necessary patient, clinical and epidemiological data. Please use the appropriate submission form. Fresh cultures in transport medium with appropriate reference to medical diagnostic material are best suited for sending the strains.

Therapy must be initiated as early as possible (at preliminary clinical diagnosis). It is carried out simultaneously with antibiotics and diphtheria antitoxin (diphtheria serum). Diphtheria antitoxin is currently not available in Austria through pharmacies. The first point of information regarding the availability of diphtheria antitoxin in Austria is the 4th Medical Department with Infections and Tropical Medicine (Department Prim. Univ.-Doz. Dr. Christoph Wenisch) SMZ-Süd, Kundratstraße 3, A-1100 Vienna, Tel: 01 60191 2407.

With complete basic immunisation and regular boosters, the course of the disease is usually mild. In case of complications, life-saving measures (intubation, circulatory support, treatment of cardiac arrhythmias) are required.

Contact

Dr. med. univ. Florian Heger

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