Safe Parasites

Tuesday, March 6th, 2012

The hygiene hypothesis has led scientists to search for safe parasites, like whipworms, to prime the immune system without actually harming the host:

In many autoimmune diseases, immune cells known as T1 cell cytokines proliferate and fight against the body’s cells, the way they do when the body detects foreign invaders.

The introduction of the whipworm appears to spur the body to produce more of a different type of helpful immune cell — T2 helper cytokines — as a defense against the worms. This separate immune response appears to help counter the inflammatory response from diseases, say researchers.

This approach differs from many available treatments on the market for inflammatory diseases. If these drugs, which tend to suppress the immune system, are given in doses that are too high, the immune system can be compromised, says Robert Summers, a professor in gastroenterology and hepatology at the University of Iowa who helped run the trials.


Whipworm from pigs appeared to be a good candidate because they don’t naturally infect humans and can’t reproduce in them. Once the eggs are ingested, they pass through the stomach to the intestine. There, the worms hatch and latch on, and apparently prompt the modulating effect in the immune system. After about two weeks, they die and are absorbed or excreted.

Dr. Summers and his colleagues demonstrated encouraging findings in two studies published in 2005. One examined 29 patients with Crohn’s disease and found that after six months, 21 were considered remitted. (There wasn’t a control group for comparison.) The other was study of 54 patients with ulcerative colitis. Patients who received TSO treatment improved significantly more than those who got placebo.

Another area of interest for TSO researchers is in multiple sclerosis, with two small studies published last year. One of these, published in the Multiple Sclerosis Journal, showed brain lesions decreased in four of five patients three months into treatment, and rebounded two months after it ended.

Some researchers say the therapy could hold promise for autism as well.

Eric Hollander, director of the Autism and Obsessive-Compulsive Spectrum Program at Montefiore Medical Center and Albert Einstein School of Medicine in the Bronx, N.Y., expects to begin recruiting for a human trial in adults with autism by the end of March.

“People are just beginning to think about modifying the immune inflammatory response to see if it has some sort of effect on behavioral symptoms,” says Dr. Hollander.

In 2005, Stewart Johnson, a portfolio manager at an insurance company in New York, and his wife were at their “absolute limit” with their then 14-year-old autistic son. Mr. Johnson says he exhibited extremely disruptive behaviors, and agitation. The Johnsons were close to putting their son in a residential facility.

Around this time their son made his yearly trip to summer camp — always a difficult time.

But one day, says Mr. Johnson, a camp counselor called, saying his son was calm and behaving better than he had ever seen. The night after Mr. Johnson picked up his son — finding he was indeed well-behaved — he saw his son’s legs were covered with many bites from chiggers, the larvae of mites. After about 10 days, the disruptive behaviors returned. “I said, ‘this can’t be coincidence,’” says Mr. Johnson.

He started doing research, heard theories that the immune system may play a role in autism, and came across the work on whipworm eggs and Crohn’s disease. He was able to obtain a supply to test on his son, though first he took the ova himself to make sure they were safe. The eggs, which aren’t yet available in the U.S., cost €300 ($396) for a two-week vial, Mr. Johnson says.

After a reduced dosage of the invisible, tasteless eggs failed to help, Mr. Johnson consulted with the supplier, OvaMed GmbH, of Barsbüttel, Germany, and bumped up the dosage. In about 10 weeks, the disruptive behaviors ceased.


  1. Ross says:

    Mayhaps someone will look at interactions between whipworm and sutella. The latter is one of the species of intestinal bugs that play a role in mediating immune response and affects ASD-type symptoms.

    Perhaps it’s too early to call Dr. Andrew Wakefield on the hotline, but I suspect that day is coming.

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