i cant speak for the rest of the world, but they farm those crayfish down in south louisianna in huge stocked lakes built just for the purpose and they feed them pelletized foods. no sewage plants involved lol. there is still a huge wild caught population but they put that on the container, its either farm raised, or wild caught. i would think that the cooking process, where you boil them alive, i would think that would kill any parasites in them, and if that doesnt, the hot pepper sauce should finish off the rest that managed to live lol.
those babys are a favorite of mine! curled tails n pinched heads! good stuff!!!
MMMMMMMMMM!!!!!!!!!!!!!!!!!!!!
edit: i forgot to mention, here they are sold live. you cook them alive. if you cook a live crawfish, the tail curls up on it really tight. if you find a cooked crawfish with a straight tail, dont eat it because it was dead when cooked and may be bad.