Hookworms and Whipworms: Our Immune System’s Attachment to Parasites

Proponents of so-called “worm therapy” believe parasites may be a key ingredient for health

December 6, 2010

When Jasper Lawrence receives a customer order, he consults his supply closet: his toilet. The founder of a Europe-based start-up, Autoimmune Therapies, Lawrence sells hookworms and whipworms he meticulously harvests from his own feces.

Each dose is individually prepared. For hookworms, Lawrence buries his waste in sand, collects the larvae that migrate to the surface, bathes them in antimicrobials and antibiotics, and finally packages them to be shipped around the world.Preparing a treatment of whipworms, parasitic roundworms that similarly invade the digestive tract, is more complex—worm ova need to be separated with a micron-sized filter before they can be packaged.

If you’d like to join the 240 plus customers Lawrence has served, all this can be yours for $2,900 per dose. However, you’ll have to leave the United States to collect and ingest your new microbial tenants. Helminthic therapy—the deliberate infestation of the gut with parasites like hookworms and whipworms—is illegal to purchase in the United States.

The controversial form of treatment is based on the hygiene hypothesis, first proposed by British epidemiologist David Strachan in 1989. The idea is that modern society’s obsession with cleanliness is depriving the body of its natural development of immune defenses.

Advocates for helminthic therapy believe that disorders such as inflammatory bowel disease and asthma occur because, in developed countries, good sewage treatment has eradicated gastrointestinal microbes that have an important influence on our immune system.

But how exactly could tiny creatures in our gut interact with our immune system in a way that benefits us? Some doctors think that helminths suppress immune response, and in doing so, prevent allergic reactions.

An allergy is an immune system overreaction to normally harmless environmental molecules like pollen and pet dander. The exact cause of allergies is still a mystery, said University of Iowa gastroenterologist Dr. David Elliott, who is supervising clinical trials on worm therapy. What does seem apparent, according to Elliott, is that helminths, which can be subject to immune system attack, pump out a protective cocktail of chemicals that dampens immune response. When the immune system is slowed, allergic reactions and other inflammatory diseases become less frequent.

Lawrence—who suffered from severe allergies throughout his life—caught wind of helminthic therapy by chance, sparking an obsession that in 2004 led him to the public sewers of Cameroon on a quest for hookworms. He returned home with a legion of parasitic invaders in his gut and claims he immediately noticed a difference—no puffy eyes, no runny nose…no allergies.

Many experts aren’t buying it. Dr. Peter Hotez of George Washington University, who is working to develop a hookworm vaccine, points out that helminthic disease is one of the most common problems of “the poorest of the poor”—the 1.4 billion people around the world who have no income at all. Parasites such as hookworms debilitate those infected and promote poverty, Hotez said. Hookworm infection in developing countries causes anemia in children, complications for pregnant women, and leads to a chronic loss of economic productivity by sapping the strength of those infected, Hotez described in an article with a team of medical experts published in PLoS Neglected Tropical Diseases journal in 2008.

Deliberate infection with helminths “makes absolutely no sense at all,” Hotez said. “The whole thing is based on flawed reasoning.”  The hygiene hypothesis, he said, ignores the fact that high rates of helminthic infection still occur in the U.S. For example, 25 percent of African Americans living in poverty have the toxicara parasite. “I don’t think allergies in the West have anything to do with the absence of hookworms,” he said.

In fact, whipworm infection is actually the leading global cause of inflammatory bowel disease, and allergies have been linked to toxicara infestation in American cities, Hotez pointed out.

But Elliott argues that real-world examples indicate differently. South Korea recently launched a major helminth eradication program, and shortly thereafter, he said, Crohn’s disease appeared on the scene. Hotez counters, however, that an increase in inflammatory bowel diseases would also reflect “massive changes” in a variety of factors such as diet, lifestyle, and gut flora that also accompany development.

For “villages in the middle of nowhere” suffering as a result of hookworm infection, Elliott supports vaccine development. He points out, though, that individuals in need of vaccination also tend to have low intakes of protein and iron— two dietary deficiencies that lead to problems from otherwise “relatively benign” parasites.

Hotez, however, believes helminthic therapy is an unsafe practice whose risks do not outweigh the benefits.

Worm supplier Jasper Lawrence acknowledged that some of his clients do develop mild symptoms such as diarrhea and fatigue when first infected, but said those symptoms soon pass. The biggest risk associated with helminthic therapy, he said, is that “it’s likely 25 to 30 percent of your friends are going to think you’re completely nuts if you admit to it.”

The federal government might think you were nuts, too. In October 2009, the U.S. Food and Drug Administration defined hookworms as an Investigational New Drug, meaning that license applications, clinical trials, and regulation would be required to sell hookworms—all of which Lawrence lacked. Currently, no one is licensed to sell worms for therapy in the United States, and FDA representative Paul Richards said that that the agency cannot project the future timing of any such approvals.

Despite the FDA’s decision, Lawrence hasn’t stopped selling his worms—he’s just moved. “I had to leave America where I lived for 23 years,” he said of his recent move to Europe where he continues to provide hookworms to patients outside of the U.S.

Whether Lawrence will ever be able to sell worms from the U.S. will depend on the outcome of clinical trials like the one Iowa’s Elliott is conducting. “The studies are marching along,” Elliott said.

Elliott’s preliminary results show that helminths can be used to keep autoimmune responses at bay. The conditions of 27 of 54 patients with Crohn’s disease improved when infected with whipworms, according to a study Elliott published in 2005 in Current Opinion in Gastroenterology. More recently, a study led by immunologist P’ng Loke published December 2010 in Science Translational Medicine followed the cellular changes in the intestinal lining of an ulcerative colitis patient who treated himself with whipworms. The study found that whipworm infection resulted in a thickening of the mucus lining of the intestines, sending the disease into remission.

Other proponents of helminthic therapy have been less successful, however. Immunologist David Pritchard at the University of Nottingham published a 2009 paper in the American Journal of Tropical Medicine and Hygiene stating that no significant relationship was found between patients infected with hookworms and their immune response. Pritchard, who declined to comment on his work, concluded in his paper that future trials using a greater number of hookworms to test for immune response could yield positive results.

Elliott’s and others’ research represents only the beginning of a lengthy process of testing and refining the treatment before it could be available for FDA endorsement—three years at the very soonest. With trials taking place at the University of Wisconsin-Madison, the University of California-San Francisco, and in various European universities, though, parasites may yet invade future prescriptions.

About the Author

Rachel Nuwer

Spending her early years exploring the bayous and beaches of Southern Mississippi, Rachel Nuwer’s love for nature and science has been a life-long romance. Rachel pursued this passion at Loyola University New Orleans where she earned a bachelor’s degree in biology. During her time at Loyola she had the opportunity to travel to Laos to research Mekong River fishes, sparking a new-found obsession with travel and exploration. This wunderlust has since taken her to 41 countries as well as encouraged her to spend a year teaching in Japan. In 2010 Rachel returned to Southeast Asia to investigate illegal wildlife trade and natural resource use in Vietnam for her ecology master’s thesis at the University of East Anglia. When not trekking through a swamp, Rachel can be found taking photos, rehabilitating stray kittens, or eating phở.



I was also able to achieve remission from Crohn’s after getting hookworms and whipworms. You can follow my progress here:
Also, there’s a wiki page that contains a ton of information on this topic, including helminthic therapy providers:
A whole lot of research articles on helminthic therapy can be found here:

Dr. Hotez argues against helminthic therapy by citing the dangers of Toxocara. In doing this he doesn’t distinguish between Toxocara and Necator Americanus or Trichuris Trichiura, which are not only different species, but actually in different genra. The Toxocara genus covers 27 species, but the two he is most likely concerned about are those of dog and cat roundworms. Since these two species didn’t co-evolve with humans they might be expected to cause health problems, which they do. So, if any lesson is to be drawn from this line of argument it is, “Do not inoculate yourself dog or cat roundworms.”

He points out that people can become anemic from helminths, and this can cause severe health problems. This is true if their numbers are very large, or if a person’s diet is very iron poor. Obviously, this is a manageable (non)issue if you are deliberately self-inoculating with limited numbers (they do not reproduce inside the host), and have a healthy diet.

He claims that, “whipworm infection is actually the leading global cause of inflammatory bowel disease.” I would like to see the citation for this, since this issue wasn’t specifically discussed in his paper.

He argued against drawing any conclusions from the increase in the rate of Crohn’s in South Korea after their helminth eradication program by saying that many other variables were changing at the same time. However, this isn’t true of a number of similar programs that have had similar outcomes in other underdeveloped countries. Some of those cases did not involve industrialization, and were simply the result of a one-time medical intervention.

D. Beales says:

The process for drug acceptance may be “marching along,” but it needs to move in double time. Millions of people suffer from autoimmune and allergic diseases which cause immense human suffering.

Those with money and compassion should be knocking on Jasper Lawrence’s door and offering to foot the bill for clinical trials to fast-track this important scientific advance.

This effort needs a philanthropist champion. Who will step to the plate?

B Liddle says:

My first dose of 35 hookworms greatly improved my multiple chemical sensitivity symptoms (rash, irritability, and restless leg syndrome) and my asthma. I have high hopes that my second dose (of 35 more) will bring further improvements. Dr. Hotez’s arguments against helminthic therapy make no sense: he says helminthic therapy is dangerous because helminths are dangerous in the wild. But the dangers in the wild are the result of hundreds or thousands of worms in each person, compared to the dozens of worms in helminthic therapy. And the worms cannot reproduce in the body (they must live part of their life cycle in the soil) so there is NO danger of over-dosing, or of passing on the worms (because toilets eliminate the soil portion of the life cycle and end the spread of worms.) Dr. Hotez’s response is more an indication of society’s knee-jerk reactions about this therapy than it is about science.

Debora Wade says:

What trials are happening at UCSF, could you specify? I haven’t heard of any.

I’ve been using necator americanus (hookworms) for my Crohn’s colitis for 3 years now. I find the worms are very effective, as long as I can keep enough alive in me, which has been a challenge.

The drugs used for many autoimmune diseases are very dangerous. For IBD, there was just a warning sent out for the commonly used biologic medicines for an increase in a certain fatal lymphoma:

WWe already know about the fourfould increase in cancer and certain infections from these drugs. And Hotez is saying that using worms are dangerous? Does he understand our available medical options?

Note that the worms used for therapeutic purposes were carefully selected. They cannot reproduce inside the body, and we are only using a controlled number. You cannot compare this to third world countries that are being exposed to 100’s of worms and have poor nutrition, or toxicara, which is not a worm used for therapy. And even if anemia were to occur, it’s easy to treat, whereas lymphoma caused by Remicade is not.

There should be large, multi-center trials right now investigating worms as medicine. Why we have to wait more years for this, or a drug made from the worms is unforgiveable. I ran out of medical options in 2007. I would have had the rest of my colon removed if not for trying hookworms. Even though it hasn’t been an easy journey for me, the option of using a natural and safe “medicine” should be an option for us all.

What can we do to fast track this research? There shouldn’t another colon lost while we wait for helmintherapy to be proven.

Ron says:

I believe the author has erred in her reporting of Dr. Elliott et al.’s findings from the studies reported in the article entitled Helminths and the Modulation of Mucosal Inflammation. In the above article Ms. Nuwer states, “Elliott’s preliminary results show that helminths can be used to keep autoimmune responses at bay. The conditions of 27 of 54 patients with Crohn’s disease improved when infected with whipworms, according to a study Elliott published in 2005 in Current Opinion in Gastroenterology.”

Below, I’ve pasted the actual findings, taken directly from the 2005 review. If you’re interested, the entire article can be obtained using google scholar or feel free to email me at and I’d be happy to send it to you. I’ve very recently become aware of helminthic therapy and have been researching it like crazy, so I’ve managed to amass several cogent articles on the topic in the preceding couple days. Being that I’ve been suffering from Chorn’s for most of my 20’s, this research is certainly peaking my interest. I’m pretty sure that I will take the leap soon, but would still like to read up a little more. I just want to make sure I’m making an intelligent decision, rather than one based on emotion. Currently, the question foremost in my mind is whether I should go with human whipworm (Trichuris trichiura)or the porcine whipworm (Trichuris suis). T. suis appears to have been studied much more widely than T. trichiura and I have seen some information concerning the transmission of disease being possible if the donor of T. Trichiura is infected with such viruses as HIV, Hep C, etc. If anyone can provide me with advice, especially that which is scientifically supported, on this matter or anything else related to helminthic therapy I would greatly appreciate it.



Dr. Elliott et. el.’s findings reported in 2005:

We first investigated the effect of colonization with T. suis on active IBD in a small open-label trial with four patients with CD and three with ulcerative colitis.[63**] The primary goal of the initial trial was to determine whether helminth therapy would be safe in people with intestinal inflammation. The
patients ingested 2500 mature T. suis ova and were observed. The patients with CD were followed using the CD Activity Index (CDAI).[64] Three of the four patients with CD achieved remission, and the fourth had a 151-point improvement in CDAI. The patients with UC were followed using the Simple Clinical Colitis Activity Index (SCCAI).[65] All three showed improvement in SCCAI, achieving scores of 4 or less. Our conclusion was that exposure to T. suis appeared to be safe in patients with IBD. We proceeded to larger trials.

We performed a larger open-label trial testing repeated dosing of T. suis in active CD.[66] Twentynine patients with baseline CDAI scores between 220 and 450 entered the study. Most had disease that was refractory to standard therapy. They received 2500 T. suis ova every 3 weeks for 24 weeks. Their disease activity was monitored at weeks 12 and 24 using the CDAI. At week 12, 75.9% of the patients responded with a decrease in CDAI of 100 or more points and 65.5% achieved remission with a CDAI score less than 150. At week 24, 79.3% experienced a response and 72.4% were in remission. There were no side effects or complications attributable to T. suis colonization. This was an open-label study without a placebo arm, but it suggests that patients with CD improve with
exposure to T. suis and that this helminth has a high safety profile.

We recently published the results of a double-blind, placebo-controlled trial of T. suis in patients with UC.[67**] This trial included 54 patients with active UC as defined by a Ulcerative Colitis Disease Activity Index (UCDAI)[68] of 4 or higher. The mean initial UCDAI of the participants was 8.7. Patients received either placebo or 2500 T. suis eggs every 2 weeks for 12 weeks. The primary end point was improvement signified by a decrease in UCDAI of 4 or more. The patients were randomly assigned: 30 to T. suis and 24 to the placebo arm. Analyzed using the intention-to-treat principle, 43.3% of the patients exposed to T. suis improved compared with 16.7% given placebo ( P < 0.04).
The patients were also followed with the SCCAI. Patients given placebo showed no improvement in SCCAI, whereas patients who received T. suis had a significant decrease in scores. The SCCAI was determined every 2 weeks and permitted evaluation of time to response. The SCCAI for patients who improved by a decrease in UCDAI of 4 or more is shown in Figure 3. Patients had significant SCCAI response by week 6.

The study also included a crossover phase. Patients who were given placebo for the first 12 weeks were switched to T. suis for a second 12-week interval. Patients who initially received T. suis were changed to placebo. The blind was maintained. Patients with a UCDAI score of 4 or more at crossover were analyzed. In the second 12 weeks, 56.3% of the patients who received T. suis
improved compared with 13.3% of patients given placebo ( P = 0.02). When the two study periods were combined, 47.8% of patients given T. suis improved compared with 15.4% of patients on placebo (Fig. 4) ( P = 0.002) as analyzed by the intention-to-treat method. If we exclude the rare patients who did not complete the study due to protocol violations, 50% of patients given T. suis
improved compared with 15.8% on placebo ( P = 0.002). This study shows that helminth colonization can effectively reduce symptoms and inflammation caused by ulcerative colitis. This was the first double-blind, placebo-controlled study of the therapeutic use of helminths. It used a single-dose regimen. Future studies using other doses, timings, or helminths will likely show even greater efficacy.

Rachel Nuwer says:

Dear Ron,

Thank you very much for your comments and interest in the article. Dr. Elliott’s paper contains several findings, but with limited space I reported only his overall conclusion from the trail of 54 patients, that “If we exclude the rare patients who did not complete the study due to protocol violations, 50% of patients given T. suis improved compared with 15.8% on placebo ( P = 0.002).”

I wish you the best of luck with your research and decision!


M. Moore says:

Having lived with Crohn’s for 25 years, and keeping myself well informed so that I can make my own decisions in treatments, I have to ask who IS Dr Hotez?

His assertion that, “In fact, whipworm infection is actually the leading global cause of inflammatory bowel disease, and allergies have been linked to toxicara infestation in American cities, Hotez pointed out.” Really… This is hubris at best.

I have never had any kind of worm infection, yet I have Crohn’s. And this is true for the majority of those who grew up in North America and other first and second world countries who are currently living with IBD, a hell far worse than most can imagine.

If whipworm infection is the cause of IBD, why has this not been made common knowledge? Oh yes, because it’s factually not true.

IBD is not even a global phenomena, it is a first and second world illness that is exceedingly rare in third world countries, where people live with intestinal worms as a matter of fact, some to ill-effect due to an overgrowth, but not all.

Ask any Gastro-Intestinal/Enterologist doctor what causes IBD, the answer remains, “No one knows.”

It seems to me that “Dr” Hotez is concerned only about getting his vaccine out, and that if proof were made that HT is actually helpful, and that absence of Hookworms and whipworm in our environment harmful, and could be a contributing cause of IBD, allergies or other auto-immune illnesses, he would be out of a job.

If he does succeed with his vaccine, there could very well be far more suffering than what the worms themselves cause.

Dr Hotez, please note: IBD has immense impact on society, in terms of earning dollars and costs to our medical systems. The individual’s life is irrevocably changed, their body appearance is likely to be altered by scars and stomas. Worse yet, each and every person who lives with an IBD (Crohn’s or Ulcerative Colitis) WILL suffer effects that would bring the most healthy individual to their knees: intense pain, malnutrition, isolation, sudden bowel movements in public (and their pants); surgical complications too numerous to list; ignorance of friends and family, loss of income and social connection; depression, anxiety, panic attacks and a higher likelihood of Post Traumatic Stress Disorder. We are often defeated by the failure of drug therapies we place our hope upon, which don’t provide remission while at the same time add to the suffere’s daily life many adverse effects. The current medical therapies only work for some who live with an IBD, some of the time, very few are well treated by them. Shame on you for your ignorance and obvious self interest.

sadie morrell says:

The idea that good sewage treatment contributes to disease is baloney. In victorian London people were dying of cholera due to poor sewage treatment.

sadie morrell says:

The most likely cause for IBD is the over prescibing of antibiotics which wipes out the good aswell as the good bacteria. It makes no sense with worm infestation in the long term. A more common -sense approach would be taking a broad-spectrum probiotic,non pharma anti-fungal and adjustment to diet.Also stress reduction technique and no alcohol. I read a comment of someone who complained of chrons disaease and was angry about something so he decided to drimk alcohol.This is in fact a self-confessed contribution to his condition.
The stress and alcohol wiping out beneficial bacteria.

Heather Mombourquette says:

I couldn’t care less about all of this blather…I am suffering with rhumatoid and I and others deserved the right to try something safer that the heavy duty drugs required to keep me having some kind of normal life. At least antibiotics will kill the worms if I need them gone. I don’t have 3 grand to buy the worms and how would I find the $$ for more dosages. Some of you people need to talk to us who are SUFFERING !!

John says:

You guys are missing the big picture, of which helminths are a part. Check out the work of Graham Rook, PhD at University College, London, Sarkis Mazmanian at Cal. Tech., or Martin Blaser at NYU (ahem). Bacteria, worms, viruses can prevent AS WELL AS trigger disease. It depends on which kinds and when.

Alternatively, see Dr. Homer Boushey’s talk at the University of California, San Francisco (

I also highly recommend the book “Good Germs Bad Germs…” (

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