"There was nothing to it," said Smith, a 33-year old financial analyst from New York. "It was drinking half a cup of salty water."
Then something incredible happened. After he had swallowed 2,500 worm eggs every two weeks for three months, his symptoms started to wane.
"I was definitely ecstatic," he said. "The symptom reduction was pretty drastic."
In Crohn's disease, the immune system mistakenly attacks the intestines, causing diarrhea, pain, bleeding and infections. But after drinking worm eggs, markers of inflammation in Smith's blood started to drop. And even his doctor "was cautiously optimistic," he said.
Today, researchers are eagerly studying the experimental therapy in multicenter clinical trials across the United States and Europe.
"Parasites are known to dampen the immune systems of their hosts," said Dr. Joel Weinstock, a parasitologist and chief of gastroenterology at Tufts Medical Center in Boston.
Weinstock said he started thinking about parasites like whipworms for Crohn's disease in the mid-1990s.
"In the United States and Europe, Crohn's disease first emerged in affluent populations living in hygienic conditions," he wrote in an editorial published today in the journal Nature. "Was it possible that improved hygiene, by ridding our bodies of parasitic worms and beneficial bacteria alike, made way for the newer problem of immune-mediated diseases? And could reintroducing parasitic worms protect people against those diseases?"
As many as 1.4 million Americans live with Crohn's disease or its cousin, ulcerative colitis, according to the U.S. Centers for Disease Control and Prevention. There is currently no cure.
Smith was diagnosed with Crohn's as a teenager. And despite multiple operations to remove part of his gut, his symptoms always returned, he said. He calculated that at his current rate of required surgeries, he would eventually run out of small intestine. If this occurred, he would require liquid feedings through an intravenous line, with potentially fatal consequences.
"That realization was pretty hard to take in," he said.
While combing the medical literature to learn about how parasites might help him cope with Crohn's, Smith learned that one could order a three-month supply of pig whipworm eggs from Europe for 3,500 euros.
One advantage of pig whipworms is that they don't cause disease in humans. The parasite stays in the gut, is unable to reproduce and dies off after two months, according to Weinstock. People who have pig whipworms can't spread them to others, and drugs can quickly rid the body of the parasite if necessary.
But Weinstock stressed that patients shouldn't ingest whipworms outside of clinical trials -- trials that Smith has declined to join.
"In clinical trials, you don't know what you're taking because you have a 50 percent chance of being in the placebo group," he said, adding that he keeps his doctor appraised of his parasite experiments. "I didn't want him to do a colonoscopy and be horrified."
Pig whipworm clinical trials are also planned or underway for ulcerative colitis, multiple sclerosis, psoriasis and type 1 diabetes, all of which are thought to arise from an over-active immune system.
"The public-hygiene measures and vaccine programs to eliminate enteric and other types of infections have vastly improved quality of life during the past 100 years, with many more lives saved than taken," Weinstock wrote. "The goal now is to reintroduce organisms into people in a controlled and predictable way, to prevent immune-mediated disease without increasing the risk of serious infection."