"Biotherapy" treats everything from irritable bowel disease to allergies with maggots, leeches and intestinal worms.
Advocates of "biotherapy," the use of animals as medical treatments, are meeting in Los Angeles.
Clinical practitioners have been reluctant to adopt these treatments, but supporters say the science is on their side.
Many parasites evolved alongside people and are essentially bio-engineered for humans.
Next time you feel sick to your stomach or suffer from severe hay fever, relief may come from swallowing a worm instead of reaching for the medicine cabinet.
Practitioners of "biotherapy" -- or the use of living animals to treat human ailments -- say science is beginning to back up their anecdotal claims that maggots, leeches and intestinal worms may be effective in the fight against everything from irritable bowel disease to allergies and psoriasis.
They're meeting this week in Los Angeles for the International Conference on Biotherapy to compare notes and strategize how to overcome the high gross-out factor that many patients and doctors have about these wiggling human parasites.
"There's always reluctance in any establishment to embrace change," said Ronald Sherman, a conference organizer. "But once medical practitioners and therapists actually try the therapy, they are our biggest supporters."
Sherman is a former infectious disease specialist at the University of California, Irvine. He also runs a lab that sells live maggots to hospitals and medical centers to treat wounds.
That cure was first described by Persian physicians in 980 and later refined in the 1920s by William S. Baer of Johns Hopkins University. But it's only in the past decade that federal regulators have approved the use of both maggots and leeches to treat problems associated with amputations and other severe wounds.
Now supporters hope the feds will approve something called helminthic therapy, which is the use of parasitic whipworms to battle auto-immune disorders like Crohn's disease or severe allergies. Filmmaker Sharon Shattuck featured these critters and their supporters in her new documentary "Parasites: A User's Guide."
"We all have a really negative opinion of parasites," Shattuck said from New York. "It equates to everything evil in our society. But not all parasites are created equal."
Shattuck profiled several people whose severe allergies prevented them from going outdoors, and who believe they were cured with the use of parasites.
"These are people at their wits' end," Shattuck said. "But the worms are able to tap into the inflammatory response and turn it down. It acts as a soothing mechanism."
Medical researchers like Joel Weinstock at Tufts University are trying to discover the science behind that mechanism. Weinstock says that modern society -- in the quest for proper sanitation and clean drinking water -- may have destroyed many of the natural intestinal parasites that evolved alongside humans.
This so-called "Old Friends Hypothesis" (first put forth in the mid-1980s) says that public health improvements in the 20th century have corresponded to a simultaneous increase in auto-immune disorders, an increase not seen in the underdeveloped world where parasites are common.
"Many of these worms are bio-engineered for humans," Weinstock told Discovery News. "We adapt to them; they adapt to us. It becomes like an organ, just like your heart, your spleen or your liver."
Weinstock says the parasites need to turn down the human's immune defenses just a tad in order to survive. But they can't turn it down too much, or both the host and parasite would die.
Weinstock's lab has published several recent papers showing how the use of whipworms can be effective for treating Crohn's disease. Weinstock's next goal is to figure out what compounds the worm produces and how they interact with the human immune system.
"If it we could figure out how it works, then maybe you can design drugs to substitute for the actual worms," he said.
Helminthic therapy for auto-immune diseases is available at private clinics in Europe and Tijuana, Mexico. It's pending FDA approval for use in the United States.
Weinstock cautions that patients shouldn't abandon existing drug treatments in the meantime.
"People shouldn't be buying these things over the Internet," he said.