It may sound downright medieval, but new research shows that the use of leeches, maggots and parasitic worms can help cure everything from irritable bowel syndrome to common allergies, according to Discovery News.

Since as long ago as 200 B.C., doctors have prescribed the use of leeches or maggots to treat wounds, skin diseases and open infections. But the practice had become largely obsolete since the rise of modern medicine. Within just the last decade, however, the use of medicinal parasites has made a comeback.

Federal regulators recently approved the use of both maggots and leeches to treat problems associated with amputations and other severe wounds, and now there is growing evidence that parasitic whipworms — intestinal roundworms that attach to the large intestine — can help regulate an overactive immune system. Some doctors say such solutions can offer relief for Crohn's disease and even common allergies.

Squeamish allergy sufferers may understandably be reluctant to ingest a worm to treat a runny nose, but those who have tried it swear by it. 

"Once medical practitioners and therapists actually try the therapy, they are our biggest supporters," said Ronald Sherman, a former infectious disease specialist at the University of California, Irvine.

The modern science behind using parasites to treat human ailments stems from a hypothesis first posited in the 1980s called the "Old Friends Hypothesis". It suggests that many parasites have evolved with humans over time, creating symbiotic relationships that may actually help our bodies stay in balance.

"Many of these worms are bio-engineered for humans," said Tufts University medical researcher Joel Weinstock. "We adapt to them; they adapt to us. It becomes like an organ, just like your heart, your spleen or your liver."

Researchers who buy into the Old Friends Hypothesis say auto-immune disorders have increased in the 20th century in the developed world, where parasites have been largely eradicated. That increase has not been seen in the underdeveloped world, where many parasites are still a part of everyday life.

Of course, there are health risks that come from ingesting parasites too, and anyone interested in using them to treat their ailments should do so with medical guidance.

"People shouldn't be buying these things over the Internet," said Weinstock. People also shouldn't do anything unsanitary with the hope that they'll contract a helpful parasite.

Currently, whipworm treatment is still pending approval with the Food and Drug Administration (FDA), but it is already available in private clinics in Europe and Tijuana, Mexico.