Most people know that botulism is dangerous, but many are confused about whether it's an infection or a case of poisoning. In fact, it can be both. Clostridium botulinum is a worldwide bacterium that inhabits rivers, soil, and the guts of mammals, fish, and shellfish. It's not an organism that normally makes its living by attacking humans. We most often encounter C. botulinum by accident.
C. botulinum secretes a neurotoxin (nerve poison) that can weaken or paralyze muscles and can even cause death. This is botulin toxin, one of the most dangerous substances known. Botulism is the condition of having been poisoned with C. botulinum toxin.