Foodborne Botulism

Foodborne botulism is the most common form of botulism (see this term), a rare acquired neuromuscular junction disease with descending flaccid paralysis due to botulinum neurotoxins (BoNTs). It is caused by consumption of contaminated food containing BoNTs.

Epidemiology

Prevalence is unknown. The annual incidence in Europe is 1/900,000 to 1/500,000. To date, about 40,000 cases have been reported worldwide.

Clinical description

Onset of symptoms occurs in adults generally within 12 to 36-48 hours (range: 6 hours-15 days) after ingestion of contaminated food. The disease is characterized by an acute or subacute afebrile symmetrical cranial nerve palsy, followed by symmetrical descending flaccid motor paralysis. Gastrointestinal symptoms of nausea, abdominal pain, vomiting and diarrhea may precede the neurological signs. In the severe forms, paralysis concerns the neck, shoulder, and proximal muscles, followed by involvement of the muscles of the upper distal extremities, the diaphragm and respiratory muscles, which may result in respiratory compromise or arrest. The sensory system and intellectual functions remain unaffected. The rapidity of onset and severity of the illness depend on the amount and type of BoNTs ingested.

Etiology

The disease is caused by consumption of home-preserved foods (homemade or traditional canned-foods, ham, pork products, vegetables, etc.) contaminated by BoNT-producing Clostridia. Contamination results from the growth and toxin production in foods presenting an anaerobic medium, a pH of ≥4.5, low salt and sugar content, and stored at ≥ 3°C. Of the seven types of BoNTs (A-G), types A, B, E and, more rarely F, are associated with foodborne botulism. Microorganisms involved are Clostridium botulinum or, very rarely neurotoxigenic strains of C. butyricum and C. baratii. Ingested and absorbed BoNTs diffuse via the blood and lymphatic system to reach the neuromuscular junctions.

Diagnostic methods

Diagnosis is essentially clinical in the first stage, based on clinical suspicion together with a 2-5 day food history obtained from the patient. Ingestion of a suspected food, absence of fever, and possible gastrointestinal symptoms are considered typical of foodborne botulism. Confirmation is based on BoNT detection in serum, stools, vomit, gastric aspirate, and suspected food samples. The detection of BoNT-producing Clostridia in stool cultures of a patient presenting typical symptomatology is generally satisfactory for laboratory diagnosis.

Differential diagnosis

Differential diagnosis of foodborne botulism includes myasthenia gravis, Guillain-Barré and Miller-Fisher syndromes, Lambert-Eaton syndrome and, in addition, intestinal and wound botulism (see these terms).

Management and treatment

Antitoxin therapy is effective when it is administrated at the onset of symptoms. The antitoxin therapy must be associated with supportive care in an intensive care unit (ICU). In Europe, the formulation currently available for adults is trivalent (anti A, B, E). A heptavalent (anti A to G) product is also available. In the USA, a bivalent (anti A, B) and a monovalent (anti E) antitoxin are available. Prevention is based on following good practice guidelines for the preparation and storage of foods with the aim of destroying spores, preventing spore germination and/or toxin production. Prompt notification to the public health authorities of suspected cases may prevent further consumption of a contaminated home-preserved or commercial food product.

Prognosis

Foodborne botulism carries an overall worldwide mortality rate of 5-10% (in the USA 3-5%). Prognosis varies according to the amount of ingested toxin and the rapidity of medical assistance. With early, appropriate treatment, the prognosis is generally good and no long-term complications are observed. Complications may occur during hospitalization, including nosocomial adverse events and respiratory failure.