Pig Worms Tested in Humans Show Early Success Against Autoimmune Diseases
Pig whipworms are 2-inch long parasites that sicken swine by burrowing into their guts. Scientists, however, are beginning to appreciate them for their curative power in humans, Bloomberg Businessweek reports in its May 20 issue.
Ovamed GmbH, a closely held German company, is starting a trial to be run in 40 European medical centers that will test use of whipworm eggs against the digestive disorder known as Crohn’s disease, one of several autoimmune diseases the eggs are being aimed at, said Detlev Goj, 50, Ovamed’s founder and the man who in 2002 got European regulators to approve the use of maggots to clean out patients’ wounds.
About 23.5 million Americans have some type of autoimmune disease, a family of illnesses that includes Crohn’s, multiple sclerosis and rheumatoid arthritis, according to the U.S. National Institutes of Health.
“This is probably the biggest market in the entire history of medicine,” said Goj, in a telephone interview.
Goj became interested in whipworms after coming across a 2005 study in which 21 of 29 patients with Crohn’s disease went into complete remission after being dosed with pig whipworm eggs. The data, by Joel Weinstock, then a researcher at the University of Iowa, seemed to support the so-called hygiene hypothesis, which holds that people have become too clean for their own good.
Danger of Hygiene
“Are there aspects of hygiene that are dangerous?” said Weinstock, who is now at Tufts University in Boston, in a telephone interview. Perhaps worms were important for the developing immune system, Weinstock said. The parasites co- evolved with us; rather than being freeloaders, perhaps they have a symbiotic relationship with humans, he said.
If so, the parasites may act on the immune system by boosting the T cells that help identify and kill infectious agents. When those cells don’t work properly, substances and tissues normally present in the body can be mistakenly targeted, causing a range of disorders.
When young kids eat dirt or sand, they’re reacting to a “basic instinct,” that allows humans to “pick up the parasites and bacteria needed to stimulate the immune system, to get it strong for the rest of their lives,” Goj said.
“Now that we’ve eliminated parasites in many Western countries, the immune system doesn’t get the required challenge anymore,” Goj said.
Ovamed has supplied sterilized batches of whipworm eggs for human trials for Crohn’s, multiple sclerosis, peanut allergies, and for symptoms of autism. One of Goj’s customers is Asphelia Pharmaceuticals Inc. The closely held San Diego-based company is projecting peak annual sales of about $2 billion in North America for its treatment for Crohn’s.
Current drugs that treat Crohn’s disease, such as Abbott Laboratories’ Humira, with sales of $5.4 billion last year, target one part of the immune system, said Russell Ellison, Asphelia’s acting chief executive officer. Asphelia is interested in the eggs because the parasites target numerous different places, he said.
“There’s a good theoretical basis for thinking this may work in other diseases,” Ellison said in a telephone interview. Asphelia plans to have raised the money by the third or fourth quarter this year to launch a phase 2 study in the U.S. and Canada in Crohn’s, he said. Three phases of clinical testing usually are required to gain U.S. regulatory approval for a treatment.
What about the yuck factor? Will people willingly infect themselves with worms under doctor’s orders? Goj doesn’t anticipate resistance.
“The eggs of the whipworm are so small they’re hard to find on a microscope,” he said. “All you see is a small cup of water.” And since the worms don’t reproduce in humans, the parasites are gone in about two weeks.
Whipworms aren’t the only invertebrates commanding attention. A 2007 study in Argentina found that MS patients who were infected with schistosoma mansoni, a parasite found in poor countries, suffered fewer relapses that those who weren’t. An immunologist at the University of Nottingham has been looking into whether pin-sized hookworms may protect against asthma, Crohn’s and multiple sclerosis.
Goj said whipworm eggs may prove effective against as many as 60 autoimmune diseases, some of which may be surprising.
For example, autistic people who hurt themselves may be suffering from an autoimmune disease. Some -- not all -- autistic children who self-harm behave better with fevers, according to research from the Kennedy Krieger Institute in Baltimore published in Pediatrics in 2007.
A fever is the immune system’s response to an intruding virus or bacteria. A 16-week clinical trial of using the eggs to treat self-harming autistic adults is ongoing at Mt. Sinai School of Medicine in New York.
Stewart Johnson, of Brooklyn, noticed his autistic son’s behavioral problems, including hitting himself until he was bloody, vanished when his son, Lawrence, had a fever or a large number of chigger bites. After consultation with his doctor, Johnson began dosing Lawrence with whipworm eggs.
“I used to have to physically restrain him several times a day,’ Johnson said. “Now he’s learning about cooking. It’s like a different world.”
The worms aren’t yet ready to be used widely, said Weinstock, who conducted the 2005 study.
“Without appropriate studies and evaluation, you’re never going to know if it’s ever any good,” Weinstock said. Patients shouldn’t infect themselves with parasites until more testing has been done, he said.