Botulism (Latin, botulus, "sausage") is a rare, but serious paralytic illness cause by a toxin, botulin, that is produced by the bacteria Clostridium botulinum. C. botulinum is an anaerobic, Gram positive, spore-forming rod. Botulinic toxin is one of the most powerful known toxins: about one microgram is lethal to humans. It acts by blocking nerve function and leads to respiratory and musculoskeletal paralysis. There are three main kinds of botulism: