What Is Botulism? What Causes Botulism?.medicalnewstoday. December 14, 2009.  Botulism is a rare, but potentially fatal infection. It is caused by toxins produced by bacteria called Clostridium botulinum. The toxins produced by clostridium botulinum are the most powerful naturally occurring toxins known to science. "Botulism" comes from the Latin word, botulus, meaning "sausage".The nervous system is attacked and results in paralysis. Left untreated, the paralysis will spread to the lungs, causing breathing failure followed by death. [ See ]