Botulism in France

Human botulism is a rare but serious neurological condition that has been a reportable disease to Santé publique France since 1986. The laboratory diagnosis is performed by the National Reference Center (CNR) for Anaerobic Bacteria and Botulism (Institut Pasteur, Paris).

Botulism is a form of poisoning caused by a bacterial neurotoxin produced by Clostridium botulinum. This strictly anaerobic bacterium is present in the environment (soil, water, and aquatic sediments). There are seven known types of botulinum toxin: A, B, C, D, E, F, and G. Human botulism is primarily associated with types A, B, and E, and exceptionally with types C and F.

Surveillance of botulism cases by Santé publique France enables the description and monitoring of epidemiological characteristics, the detection of clusters of botulism cases for which product recalls may be necessary, and the identification of emerging new strains or new high-risk foods.

An infection primarily caused by food

There are three main forms of botulism

• the most common form is foodborne botulism. This is a food poisoning caused by ingesting food containing preformed botulinum toxin;

• colony-associated botulism is a foodborne illness caused by the endogenous formation of botulinum toxin following the germination in the intestine of ingested Clostridium botulinum spores. The most well-known form is infant botulism;

• finally, iatrogenic botulism (injection of botulinum toxin for medical or cosmetic reasons) or injury-related botulism (foodborne illness caused by the growth of Clostridium botulinum and the production of botulinum toxin from contaminated wounds, for example among intravenous drug users).

Foodborne forms are the most common (79.5% of reported outbreaks between 2018 and 2024). The foods most frequently implicated in foodborne botulism in France are home-cured meats and deli meats, and home-canned or artisanal preserves.

Prevention based on best practices (preserves, cold cuts)

Since homemade preparations (preserves, deli meats) are the primary source of contamination, it is essential to apply appropriate sterilization and preservation techniques1. Similarly, it is important that products from the food industry be stored according to the manufacturer’s instructions, which must be clearly displayed on the packaging, and consumed before the best-by date expires.

Food preservation methods for industrially or artisanally produced foods (temperature, salt concentration, pH) must be strictly followed to prevent the formation of Clostridium botulinum spores.
Furthermore, botulinum toxins are heat-labile and are destroyed by boiling for 10 minutes.

Botulism causing neurological damage

The incubation period averages 12 to 72 hours (range: 2 hours to 8 days) for foodborne botulism. However, this duration and the severity of botulism symptoms depend on the amount of toxin ingested and the type of toxin involved.

Botulism is an acute neurological condition without fever. It is characterized by bilateral cranial nerve involvement and descending paralysis. The initial symptoms include:

• ophthalmological (accommodation disorder, mydriasis, ptosis);

• gastrointestinal (abdominal pain, nausea, vomiting, and diarrhea);

• neurological symptoms involving the cranial nerves (diplopia, dysarthria, dysphonia, and dysphagia).

These symptoms may be exacerbated by signs of flaccid, descending, and symmetrical paralysis (dry mouth, difficulty swallowing, fatigue, and weakness in the limbs). In advanced forms of botulism, signs of paralysis are observed: paralysis of the limbs and paralysis of the respiratory muscles.

Death from botulism is rare and varies depending on the type of toxin involved, with types A and E causing the most severe forms.

Confirmation of the diagnosis of botulism is achieved by detecting and typing the botulinum toxin in serum using the mouse lethality test. Clostridium botulinum is detected in patients’ stool and in suspect food items via enrichment culture and gene amplification.

Management of symptoms

Administration of botulinum antitoxin within hours or the first few days after symptom onset may shorten the length of hospitalization. This antitoxin will be supplied by EPRUS to the pharmacy of the hospital where the patient is being treated upon specific request (Temporary Use Authorization).
Treatment for botulism primarily involves managing symptoms. Mechanical ventilation (artificial respiration) may be necessary in some cases.