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Can Parasites Heal the Gut?

The Inflammatory Bowel Disease (IBD) had ballooned from 1 case per 10,000 people, to 1 in 250—a forty fold increase in the space of two or three generations. As observed by Dr. William Allchin[3], IBD disproportionately struck the upper classes—"well-to-do, well-nourished persons in excellent health."

Recently scientists have pointed out that there could be some connections between the prevalence of IBD and the absence of parasites in the last half century. In this article, we will examine if there is a link between parasites and IBD.

When we try to pick out anything by itself, we find it hitched to everything else in the Universe

John Muir

What's IBD

In medicine, inflammatory bowel disease (IBD) refers to a group of inflammatory conditions of the colon and small intestine. There are two main forms:
  • Crohn’s disease[7]
    • The cause of Crohn’s disease is unknown, but researchers believe it is the result of an abnormal reaction by the body’s immune system.
  • Ulcerative colitis (UC)[6]
    • People with UC have abnormalities of the immune system, but whether these problems are a cause or a result of the disease is still unclear.
    • The incidence of UC tended to increase first in its patients, followed by a spike in the incidence of Crohn's Symtoms[3].

When people from developing tropical countries immigrate to cleaner, temperate ones, they seem to have an even greater propensity to develop IBD than natives[3]. For example, South Asian immigrants to the U.K. have less IBD than native Britons, but their U.K-born children have two and a half times the risk. And India, which has developed rapidly in recent decades, has also seen an increase of IBD. The prevalence first spiked in regions (such as Kerala) that saw the earliest improvements in public hygiene.

That's why scientists like Joel Weinstock, a gastroenterologist, suspect the prevalence of IBD is an environmental factor.

ParasitesNow and Then[3]

Parasitic worms, often referred to as helminths, are worm-like organisms living in and feeding on living hosts. Those that live inside the digestive tract are called intestinal parasites. They can live inside humans and other animals. Parasites like hookworm were ubiquitous during our evolution. Even Otzi had his worm. Otzi was the 5300-year old man discovered in an Italian glacier with whipworm in his gut.

Helminths are remarkably efficient at establishing chronic infections with limited inflammatory pathology in some of their hosts, while in other infected people they can cause severe morbidity[14] and they are a major health problem worldwide.   Based on estimation, hundred of millions of people carry the parasite today.

Hookworm, one of the helminths, has mostly disappeared from the U.S. in the early twentieth century, the result of protracted eradication efforts and better sanitary living condition.  However, over the same period, an increase of autoimmune and allergic disease in the developed world has been reported.

A group of people named Tsimane live on the edge of the Amazon jungle, whose living is still close to Stone Age living. Anthropologists Michael Gurven and Hillard Kaplan who have studied them find that: In Tsimania, 

  • The prevalence of autoimmune disease is 1/40th what it is in New York City.
  • And parasites are universal.  For example, nearly everyone has hookworm.

In 1990s, a Japanese scientist named Koichiro Fujita worked in Borneo.  He had also noticed that Bornean children had exquisite skin and no allergies, but they harbored plenty of parasites.  

Is there a link between parasites and autoimmunity?

Parasites and IBD

At beginning, scientists had explicitly linked IBD with patients' socioeconomic status while they are young.  The cleaner one's circumstances during childhood, scientists found, the greater one's chances of developing IBD in adulthood.  Hot, running water and a flush toilet while growing up elevated one's risk later.   Drinking from a well or stream, and defecation in an outhouse, or the bushes, lowered it.

This has led scientist Joel Weinstock, the chief of gastroenterology and hepatology at Tufts-New England Medical Center, to wonder that could it be something that protected people from developing IBD had disappeared.  Later his research has make him believe that it's the loss of parasites.

Host Immunity

T helper cells (Th cells) are a sub-group of lymphocytes, a type of white blood cell, that play an important role in the immune system, particularly in the adaptive immune system. They help the activity of other immune cells by releasing T cell cytokines.  Understanding exactly how helper T cells respond to immune challenges is currently of major interest in immunology.  

There are two major subtypes of helper T cells known as Th1 and Th2[10,13]:

  • Th1
    • Th1 is the host immunity against intracellular bacteria and protozoa.
    • The painful, red swelling around an infected cut or pimple exemplified a Th1 response.
  • Th2
    • Th2 is the host immunity against multicellular heminithes and blood-feeding insects.
    • The itchy red bump of a mosquito bite typified Th2.

Immunologists thought that the two responses were mutually exclusive.  If you turned one on, the other would shut off, and vice versa[9,10].  Gastroenterologists viewed IBD as a resulting from excessive Th1.  Introducing worms to this situation could presumably ramp up the Th2 response, and shut down the chronic Th1-type inflammation driving the malady.

In another case study, a person named Rick has inflicted himself with helminths and got his IBD under control. Later working with P'ng Loke[5], a Parasitologist at NYU, they have found that the worms boosted mucus production. Scientists have noted that IBD often presents with a relative paucity of mucus.   So one line of thinking holds that IBD results from having lost this protective layer.  Rick's case suggested that worms could restore the mucous layer, a "bystander effect," Loke says, of trying to fight off worms.


The gut, perhaps our preeminent immune organ, serves as the primary command center where sets the tone for immune and metabolic functioning far and beyond.   Perhaps most essential, for the immune system, peacekeeping is an active process, not an absence of process.  Equilibrium is not necessarily the default setting, but a talent that's developed.  In this context, allergic disease is seen as a parasite control mechanism that, absent real parasites and key microbes, has spun out of control[3].

Joel Weistock[11] argued that over millions of years of coexistence, the human immune system had adjusted to the presence of parasites, and even come to rely on it.  So the sudden disappearance of parasites in the twentieth century left the immune system off balance.  One consequence of that imbalance was a greater predisposition to IBD.  No infectious agent caused this disease, in other words; it was prompted by a conspicuous absence[3].  And no vaccination or antimicrobial would fix it.  Addressing the problem would require an ecosystem restoration of sorts— such as worm therapy[12].  Experiments on animals had shown that worms could prevent not just IBD, but other inflammatory and autoimmune diseases including autoimmune diabetes and multiple sclerosis.

"Hygiene has made our lives better," Weinstock says.  "But in the process of eliminating the ten or twenty things that made us sick, we've gotten rid of exposure to things that made us well."


Only worms that had coevolved with a given host conferred benefit.  New arrivals on the other hand, could cause significant disease.  In Australia, repeated outbreaks in humans of the dog hookworm Ancylostoma caninum during the 1990s underscored this important point.  In this case, the dog-adapted hookworm successfully colonized humans, suggesting a new species in the making. But the parasite didn't establish itself very gracefully. Unlike human hookworm, these dog worms caused severe inflammation, ulcers, and enteritis.  In Japan, outbreaks of anisakiasis, a worm acquired from undercooked or raw fish, also illustrated this point.  The helminth, which was native to seals and dolphins, could cause major smptoms, even life-threatening illness, in people.

Joel Weistock has chosen a porcine whipworm species called Trichuris suis in his experiments on volunteers. However, Rick mentioned in this article reasoned that: If he hoped a parasite would manipulate his immune system, then the parasite should be adapted to the human organism. So, he decided to acquire the human whipworm, Trichuris trichiura.

However, every one searches for worm therapy has found that the major obstacle isn't locating the worm; it is ensuring one find only the worm she wants. The parasite tended to co-occur with other helminths, like the giant roundworm, Ascaris lumbricoides, the most prevalent human-adapted worm on earth. Ascaris's capacity to protect from IBD was untested and it was disturbingly large.

That's why commercial company like Ovamed comes in play. Ovamed produces pharmaceutial-grade whipworm eggs on Weinstock's protocol and is licenced by the University of Iowa (from where worm theory was developed by Joel Weistock and his colleagues). This German company harvests the eggs from miniature Danish pigs raised in hyperclean conditions, has developed a manufacturing processing that meet the approval of European regulatory authorities.


  2. Worm Therapy
    • This company seems to be operated off the US border and located in Tijuana, Mexico.
    • Note that worm therapy is not approved by FDA in USA.
  3. An Epidemic of Absence — A New of Understanding Allergies and Autoi mune Diseases (excellent book)
    • Transient worm infections don't really modulate the host immune system.
    • Only chronic infections with sufficient numbers—ane with the right species—have the power to change how your immnue system works.
  4. Dogs Make Me (and You) Wild: Ten Effects of Dogs on Dog People
  5. Loke Lab - Microbiology
  6. Ulcerative Colitis
  7. Crohn's Disease
  8. His parasite theory stirs a revolution
  9. CELL-MEDIATED IMMUNITY: Cell-cell interactions in specific immune responses 
  10. Th1 cells switch off Th2 cells and vice versa
  11. Joel V. Weinstock, MD
  12. Eat Your Worms: The Upside Of Parasites
  13. Limitations to the Th1/Th2 model
  14. Risk Factors of Liver Diseases
    • Hepatic cholangiocarcinoma has peak incidences in Northern Thailand, which is caused by chronic infection with the liver fluke, Opisthorchis Viverrini.
  15. Extra Vitamin D May Ease Crohn's Symptoms
  16. Is Carrageenan Safe?
    • If you have IBD or other gastrointestinal problems, try to cut out carrageenan (a thickener and fat substitute in a variety of dairy and nondairy products) temporarily to see if your symptoms improve.
  17. H. pylori — Old Foe or Friend? (Travel and Health)
  18. Are Dogs More Protective For Children’s Health? (Travel and Health)
  19. The secret of the legume: Bond Life Sciences Center researchers pinpoint how some plants fix nitrogen while others do not
    • “There’s this back and forth battle between a plant and a pathogen,” said Yan Liang, a co-author of the study and post-doctoral fellow at MU. “Rhizobia eventually developed a chemical to inhibit the defense response in legumes and make those plants recognize it as a friend.
  20. Graham A. W. Rook. Hygiene hypothesis and autoimmune diseases.  Clin Rev Allerg Immu 2012 Feb; 42(1):5-15.
  21. Virus May Be a Trigger to Celiac Disease, Study Says (important)
  22. Using genomics to fight deadly parasitic disease
    • Nearly a quarter of a million people die from snail fever (a parasitic disease called schistosomiasis, also known as bilharzia) every year, just in sub-Saharan Africa.
  23. Justin Sonnenburg on "The Good Gut"