One problem I have with infesting people with parasites is that those not known to be harmful organisms could become harmful. Hulda Clark found that pollutants and toxins sometimes made it possible for some parsites to live in places where they could damage the body and for parasites to carry their own parasites (bacteria, viruses, yeasts, maybe prions) which could infect or over grow in humans. The people living now are exposed to and have ligh levels of pollutants in their bodies.
I read that one treatment for refractory dysbiosis was to sterilize the intestine then innoculate with feces from a healthy person.