Botulism A05.1

Botulism is a rare, life-threatening disease caused by neurotoxins, characterized by a flaccid, descending paralysis that begins with paralysis of the cranial nerves and can lead to weakness in the extremities and respiratory arrest. It is caused by 4 different neurotoxins (type A, B E, F) of Clostridium botulinum.

Rare disease in western industrialized countries (Germany < 10 registered cases/year); feared as a bioweapon.

Clostridium botulinum: Anaerobic, gas/spore-forming bacteria. The heat-resistant spores are widespread. They can germinate in the absence of air and form toxins. Exposure to the neurotoxin occurs through ingestion of the toxin (foodborne botulism), bacterial colonization of a wound (wound botulism) or the intestine (infant botulism and botulism due to intestinal colonization in adults) as well as through cosmetic or therapeutic injections of the toxin in high concentrations (iatrogenic botulism). The toxins can be inactivated by heating to 100°C for 15 minutes. Bulging (cambered) cans are always suspicious! Contaminated food is otherwise inconspicuous.

The botulinum neurotoxin inhibits the release of acetylcholine at the neuromuscular junction and is produced by the anaerobic, gram-positive bacterium Clostridium botulinum and rarely by related species (C. baratii and C. butyricum).

Botulinum toxin type A (BoNT) is the primary virulence factor and the causative agent of botulism. BoNT, which is considered the most potent biological substance known, is a zinc metalloprotease that specifically cleaves SNARE proteins at neuromuscular endplates, preventing the exocytosis of neurotransmitters, which leads to muscle paralysis.

BoNT is now used to treat numerous conditions caused by overactive or spastic muscles and is used extensively in the cosmetic industry due to its high specificity and the extremely low doses required for a long-lasting pharmacological effect (see Botulinum toxin A below). In addition, the ability to form endospores is crucial for the pathogenicity of bacteria. The transmission of diseases is often facilitated by the metabolically inactive spores, which are highly resistant to environmental stresses and can persist in the environment under unfavorable conditions. Infections with infant botulism and wound botulism are caused by the germination of spores into neurotoxin-producing vegetative cells, whereas foodborne botulism is due to the ingestion of already formed BoNT.

Borulinum spores could be used as bioterrorist weapons. Toxin exposure could result from deliberate contamination of food or beverages or aerosolization. The neurological symptoms are similar regardless of the route of exposure. Treatment includes supportive care, intubation and mechanical ventilation if necessary, and administration of botulinum antitoxin. Certain neurological conditions (e.g. Prior to the publication of these guidelines, there were no comprehensive clinical treatment guidelines for the treatment of botulism (Rawson AM et al. 2023).

Food botulism: Usually 12 - 36 hours

Wound botulism: Approx. 10 days

Beginning with gastrointestinal complaints (nausea, vomiting, etc.); then development of peri-pheric paralysis: first on the cranial nerves with pupillary paralysis (dilated pupils), double vision, ptosis, dysarthria and/or dysphagia. The paresis can progress caudally within hours to days and cause respiratory paralysis. Furthermore, dry mouth, constipation, possibly paralytic ileus, urinary retention. Sensory disturbances, changes in consciousness or fever are typically absent.

Typical clinic with sudden onset of neurological symptoms (possibly in several people) after eating (privately) canned or smoked food.

Detection of botulinum toxin in food residues, vomit, gastric juice, stool or serum.

In the case of wound botulism, it is possible to cultivate the pathogens from wound cultures.

Myasthenia gravis (edrophonium chloride test, etc.), diphtheria, poliomyelitis, atropine poisoning, stroke, etc.

Toxin elimination from the gastrointestinal tract (gastrointestinal emptying). Antitoxin from the horse should be administered as soon as possible after the laboratory samples have been taken in cases of foodborne botulism to bind the toxins still circulating freely in the serum (conjunctival test beforehand to rule out an allergic reaction).

In case of wound botulism, surgical treatment and penicillin. Symptomatic: e.g. mechanical ventilation for respiratory paralysis

Mortality in foodborne botulism under intensive medical treatment < 10 %, untreated up to 70 %.

Store vacuum-packed food in a cool place (< 8°C to prevent germ multiplication). Meat should always be heated twice when preserving (to inactivate spores). As honey can be a source of infant botulism, children < 1 year old should not be given honey. Observe expiry dates, boiling at 100°C for 15 minutes destroys the toxin.

An evidence-based guideline provides healthcare providers with recommended best practices for the diagnosis, monitoring and treatment of individual cases or outbreaks of foodborne, wound and inhalation botulism and was developed after a multi-year process with several systematic reviews (Rao AK et al. 2021)

1. Czerwiński M et al. (2023) Foodborne botulism in Poland in 2018-2021. Przegl Epidemiol 77:233-240.
2. Rao AK et al. (2021) Clinical Guidelines for Diagnosis and Treatment of Botulism, 2021. MMWR Recomm Rep 70:1-30.
3. Rawson AM et al. (2023) Pathogenicity and virulence of Clostridium botulinum. Virulence 14:2205251.