There's a guy (Jasper Lawrence, who had a horrible allergy problem) had heard of a study where they were testing to see if allergies was related to parasites. He was rejected from the study, so, long story short, he ended up flying to northern Africa and walking around barefoot to get hookworm. He now monitors and manages his hookworm infection with low doses of anti-parasite medication, and he sells soil infected with hookworms so that you, too, can get infected by hookworm and reduce/eliminate your allergies. Oh, and his allergies are gone.

I read about it here: https://www.ksl.com/article/20838871/man-infects-self-with-h...

But there are lots of stories and some studies on the subject as well. The original hypothesis was proposed in 1989 by David P Strachan. According to the theory, many modern diseases have gotten out of hand and are rapidly growing in industrialized western countries because of chlorinated drinking water, vaccines, antibiotics and the sterile environment of early childhood. Moreover, it is theorized that since we have become so good at preventing infections, we have upset the internal balance and ecology in our bodies. One missing element of hyper-clean and sterile environments is that our inflammatory responses do not function as they should. Parasites and bacteria play a symbiotic role in preserving our health.