>>2048584599% of industrial agricultural output in the developed world is grown in crops sprayed with human feces. This contains helminth (worm) eggs which are resistant to UV and chemical exposure and eventually end up in your food. Once you flush the toilet into municipal water supply, the cycle starts all over again.
If you aren't taking antiparasitics, and you eat uncooked industrially-produced food, it is almost certain you have an overgrowth of parasites