Botulism is a rare but life-threatening neuroparalytic disease caused by neurotoxins primarily produced by the spore-forming bacterium, Clostridium botulinum (C. botulinum). Two other types of bacteria that occasionally cause botulism are C. butyricum and C. baratii.
There are seven distinct nerve toxins (A through G). Toxins A and B (the most common and most potent), E, and F cause botulism in humans when the toxin or toxin-producing bacterial spores are ingested, when toxin is released in an infected wound, or, in rare instances, when spores are inhaled. These toxins damage tissue gaining access into the bloodstream and eventually bind to the presynaptic membrane at the neuromuscular and autonomic nerve junction. Acetylcholine is inhibited, preventing muscle cells from contracting and causing paralysis of the arms, legs, and respiratory muscles. Toxins C and D affect nonhuman animals (e.g., cows, birds); toxin type G (rare) was isolated in Switzerland where it was implicated in sudden, unexplained death (non-neuroparalytic illness) in autopsies of 5 patients in 1977.