It turns out there's a lot of evidence that our immune systems have evolved to cope with parasitic worms of one kind or another, so there's a regulatory benefit to having them in your system. Researchers are studying how various autoimmune disorders (allergies, asthma, Crohn's disease, multiple sclerosis, etc.) can be significantly lessened, if not eliminated, by helminthic therapy, as it's called.
Do not, by the way, google for images of hookworms, because they are fucking terrifying.
So the question is:
Deliberately infesting yourself with a parasitic organism for the health benefits. How squicky is that?