Smurfs are a lot like Taenia saginata, the pork tapeworm, in their lifecycle. The blue smurfs we all know and love are but one part of the smurf lifecycle, a gravid proglitid structure that when ingested results in thousands of oncospheres hatching and burrowing into the intestinal wall to reach permissive replication sites such as the gut, the eye, and the brain. Long term survival and replication of these oncopsheres results in cysticercus formation in these tissues as a means to disperse more eggs. I suspect Gargamel would slowly digest his own tissue from a lack of nutrients as he went blind and quite mad from the persistent inflammatory disease. He would die a mindless, blind fool in a pool of his own bloody excrement.