Summary
Botulism is a neurological disease characterized by descending flaccid paralysis. Annual incidence in Western countries is estimated at 1/2,000,000. The characteristic clinical signs are flaccid and symmetrical cranial nerve palsy, followed by symmetrical descending paralysis of voluntary muscles. Initial symptoms include blurry vision (accommodation defects, diplopia), followed by autonomic symptoms (dry mouth, dysphagia, dry eyes, mydriasis, and constipation). In the severe forms, paralysis concerns the neck, shoulder, and proximal muscles, followed by involvement of the muscles of the distal upper extremities, the diaphragm and respiratory muscles, which may result in respiratory compromise or arrest. The sensory system and intellectual functions are unaffected. Botulism is caused by the botulinum neurotoxin, which is synthesized by Clostridium botulinum and certain related clostridia, rod-shaped, strictly anaerobic and sporulating bacteria. There are seven types of botulinum neurotoxin (A to G) with different antigenic properties. Types A, B, E and, more rarely F, are associated with human botulism. Incubation usually lasts 12 to 36 hours, sometimes up to 5-8 days. Clinical manifestations are similar, whatever the mode of acquisition. Food-borne intoxication caused by consumption of foods contaminated with botulinum toxin (homemade or traditional canned-foods, ham, pork products etc.) is the most frequent form of botulism in adults. Intestinal colonization by C. botulinum and in situ toxin production is observed in young infants (infant botulism) and certain adults with risk factors. Botulism through infection of wounds is rare and mainly occurs in injection drug users. Confirmation of botulism is based on the detection of botulinum toxin in serum, stools, and/or food samples. In addition, stools, wound sites and food samples can be screened for botulinum toxin-producing Clostridium. Differential diagnosis includes myasthenia, Guillain Barré syndrome and Miller-Fisher syndrome (see these terms). Botulism treatment is symptomatic. Anti-toxin therapy is effective when it is administrated at the onset of symptoms. 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. Prognosis is variable according to the amount of ingested toxin and the rapidity of medical assistance. *Author: Dr M. Popoff (April 2008)*.
