Hello! 90% of humans have parasites. That's just a natural part of being an animal. Humans are animals and animals carry parasites. While parasites live in your body they secrete toxins that can make you very sick. Their feces, urine and dead bodies all cause a wide variety of symptoms including chronic fatigue, skin problems, etc. 70% of parasites that affect humans are microscopic - Malaria for example - while the other 30% are of the visible variety. SO, some people can do a parasite cleanse and will never see a visible parasite if they have any of the microscopic variety.
MOST people will never see a parasite at all even if they pass a visible one in their stool - think about it, how many people ever even look at their stools?
Someone without parasites (a rare thing indeed!) will not have any die off symptoms. I hope this helps!