August 31, 1999
Join a Discussion on Alternative Therapies
By ANDY NEWMAN
For most of Western history, the average child walked around with a bellyful of parasitic worms: pinworms, tapeworms, hookworms. Then modern civilization came along, put shoes on the children's feet, installed sewers and stopped using human waste as fertilizer, and the worms mostly disappeared.
But there may be a downside to all this hygiene. Children in industrialized countries, which are relatively worm-free, have a much greater tendency than those in other countries to grow into adults with autoimmune disorders (in which the body is attacked by its own immune system), like rheumatoid arthritis, multiple sclerosis, lupus and inflammatory bowel disease.
Maybe this is a coincidence, but maybe not. Recently, researchers at the University of Iowa gave a drink containing the eggs of a half-inch-long parasitic worm to six people suffering from acute, chronic inflammatory bowel disease. Five went into remission, and the sixth improved substantially.
None got sick from the worms; all gradually relapsed after the worms left their systems. (For safety, the researchers used worms that normally live in pigs' intestines and were unable to reproduce and persist in their human hosts.) "Every one of those patients is begging to be re-treated," said the lead researcher, Dr. Joel Weinstock.
The sample was admittedly small. But the preliminary results, which made a big splash at an American Gastroenterological Association conference in May, could offer hope for the hundreds of thousands of Americans who suffer from inflammatory bowel diseases, mainly Crohn's disease and ulcerative colitis, which cause chronic and often bloody diarrhea, pain and weight loss.
"It's very interesting work," said Dr. Stephen Hanauer, co-director of the inflammatory bowel disease center at the University of Chicago School of Medicine and an international authority in the field, who was not connected with the study. "It needs to be substantiated in controlled trials, but there is some biologic sense to it."
Dr. Weinstock is one of a growing number of subscribers to what is known as the hygiene hypothesis -- the idea that the war on germs and other contaminants is producing some unintended consequences.
A Swedish study in The Lancet, a medical journal, found this year that children of families that used antibiotics and vaccinations had more allergies than children of families that avoided them. And researchers in Israel found that rats raised in germ-free environments developed more arthritis and diabetes than other rats.
Dr. Weinstock's team believes that Crohn's disease flares up when an immune system that has evolved to deal with multiple invaders finds itself unable to adapt to a more sterile environment.
Dr. Hanauer says the concept seems sound.
"There are other potential explanations," he said. "But this is an interesting concept because it is holistic across the other immune diseases."
Dr. Weinstock got the idea for the worm cure three years ago while editing journal articles on parasites of the liver and intestine. In looking over decades of literature, he kept running across the idea that all well-adapted parasites perform some useful function for their hosts, if only to assure that the host survives to give them a home.
He and his colleagues began wondering about worms called helminths, which have been with humans for millions of years. "We were racking our brains trying to think of what the benefits of these guys might be," he said. "Then the autoimmune disease hypothesis came up."
The hypothesis is based on the widely held theory that the immune system, when challenged by an invader, fights back with white blood cells of the Th1 or Th2 type. Th1 cells attack the body's infected cells, while Th2 cells go after dangerous microbes before they even invade the body's cells.
Dr. Weinstock thinks inflammatory bowel diseases develop when the body overreacts to the normal bacteria in the digestive tract, unleashing a salvo of Th1 cells that end up damaging the colon and bowel themselves. Helminths, he says, trigger a Th2 response, which dampens the Th1 response.
The helminth cure, if it proves effective, could have the side benefit of rehabilitating the reputations of parasitic worms, which have remained widely reviled even as some intestinal bacteria like acidophilus and lactobacillus have become popular over-the-counter supplements.
The parasites, Dr. Weinstock said, have been victims of unfair if understandable prejudice.
"Some worms do cause problems," he said, "but some cause very few problems."
On the other hand, he cautioned against ingesting worms without proper medical supervision. For this reason, he would not identify the precise species of helminth he uses in his research.
"We don't want people going off to Mexico or who knows where else trying
to expose themselves to helminths that are not controlled and getting who
knows what kinds of consequences," he said. "If people run out and get
hurt, I'm not going to feel really good about this."