There have already been attempts to treat immune-mediated diseases by artificially infecting them with helminths. Because Trichuris suis can be obtained from experimentally infected pigs, the parasite has been used in immunotherapy research to artificially infect people. There are some clinical reports that patients who ingested T. suis had a reduction in several immune disorders such as Crohn’s disease (73) and ulcerative colitis (74). However, some clinical trials have shown no therapeutic effect (75, 76) and in a large study using meta-analysis, T. suis showed no apparent benefit for inflammatory bowel disease patients (77). Besides, therapeutic benefit by parasites may be limited to the infection sites but not systemic. A clinical trial of artificial infection with T. suis, a parasite of the intestine, did not provide relief from allergic rhinitis (78). Furthermore, infection with live parasites for therapeutic use may not be practical, and can sometimes cause other unintended consequences. There is also a risk of inadvertently transmitting pathogenic parasites. For this reason, it is imperative to identify immunomodulatory molecules and apply them to treatment of immune-mediated diseases rather than using live parasites. In order to ensure safety, it is also necessary to elucidate the detailed mechanism of how the molecule regulates immunity.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8977410/

You're right that people are trying it.

I never said no one was, I said only shitty doctors would prescribe it.

I didn't see anything about it being prescribed, but there have been studies.

The studies just show it doesn't work.