In developed countries like Canada, parasitic worms have been all but eliminated. But scientists are now saying these worms could help boost the immune system, providing valuable protection against conditions from Crohn’s disease to multiple sclerosis, the Telegraph reports. At Nottingham University, scientists are looking at whether infecting patients with hookworms—which burrow through the skin and into the body—can help ease asthma symptoms. And in the U.S., researchers are trying to determine if infecting multiple sclerosis sufferers with parasites will slow the disease’s progression. Advocates of the “hygiene hypothesis” say that, today, we’re simply too clean: evolved over thousands of years to co-exist with parasites, and their elimination is now damaging our health. While having worms isn’t necessarily a good thing, “maybe there is a positive side […] that we can exploit for new therapies for allergies, asthma, and so on,” Professor Jan Bradley, an expert in parasite immunology at NU, told the paper. Drug companies may even be able to replicate their beneficial effects.