The environment of ages past has shaped who we are today, even (or especially) the difficult, unpleasant stuff – this is the foundation of ancestral health. Take exercise . Early man’s daily life was one of frequent, constant activity interspersed with infrequent bouts of intense activity. Hard exercise is, well, hard and physically unpleasant in the moment, and constant low level activity  is often untenable given modern schedules, but both make us stronger, healthier, and ultimately happier. Intermittent fasting , while difficult, can be beneficial when artificially imposed today because our genome evolved under periods of nutritional stress where food was scarce. Going without food from time to time was expected; it was our genome’s evolutionary backdrop. Our bodies evolved with these hardships as assumed and inevitable aspects of the environment. Our modern bodies function best when exposed to these hardships.
What about another almost unavoidable aspect of the ancestral environment – parasites? Do our bodies expect and function best with a few (dozen) worms along for the ride? You know about gut flora’s effect on our immune response  and overall health, but does the fact that our immune systems evolved with the presence of various helminthic  worms also have implications for our health?
A growing number of researchers think it’s likely. They posit the “Old Friends Hypothesis ,” which suggests that helminthic worms and other parasites commonly assumed to be wholly pathogenic are actually “old friends” that can provide a steady, low-level anti-inflammatory buffer that reduces the incidence of autoimmune diseases like celiac, multiple sclerosis, type 1 diabetes , and Crohn’s disease. Populations with high parasite loads tend to display a remarkable absence of autoimmune disease as well as distinctive genetic markers that bias them toward higher baseline inflammation levels that are only held back by the presence of worms. Many of the alleles associated with having parasites are also associated with celiac, multiple sclerosis, colitis, diabetes, and rheumatoid arthritis , which suggests parasite/host co-evolution. In the presence of worms, maybe those alleles become harmless.
If you’re wondering why worms would ever be a “good thing,” you have to realize that helminthic worms are stubborn. They get lodged in there. They can’t really be removed by our immune system  because the inflammatory response required to do so would damage the host (that’s us) more than keeping the thing around would damage the host. In turn, the worm doesn’t want to overstay its welcome by taking too much from the host and killing it. So, the host adapts to its inextricable bedfellow, while the bedfellow adapts to its host by modulating the host’s inflammatory response. And in time, it becomes reliant on the parasite, and the parasite becomes an external fixture of our immune system. It’s not really part of us, but we treat it like it is because it’s been there for so long over so many generations that we can’t function without it. We’re used to the inflammatory buffer. Humans have encountered many different species of helminth, and most, if not all of them modulate immune function in unique ways .
And when it’s no longer there, when we move to cities and stop having parasite-enriched dirt under our fingernails, when we enact widespread sanitation measures and clean up our water and throw our trash away in nice neat bins that get cleaned every week, there are unforeseen consequences. Even though infectious disease rates and deaths from infectious disease drop, and more infants make it through to adulthood, there’s no free lunch. As long as the old friends are there to buffer against the elevated inflammation, autoimmune disease is relatively absent . When the old friends are withdrawn (like through anti-helminthic therapy), autoimmune disease and allergies increase .
So, what should we do? Go spelunking in a rural Indonesian porta-potty? Take shots of Ganges River water? French kiss a pig? You’d actually be surprised. One guy cured his asthma by walking barefoot through the latrines of Cameroon . While that may be the “most Primal” way to do things, it’s not advised. As mentioned earlier, there are a lot of parasites out there whose effects we don’t quite understand and there are plenty whose effects we know to be pathogenic. Inoculating yourself with random wild helminths could cure your allergies or it could give you tapeworm (or both, I suppose).
Trials have been completed and more trials are underway, and the results are extremely promising thus far. Just so you know I’m not pulling your legs, let’s go through a few of them:
Inflammatory bowel disease (Crohn’s, colitis): Epidemiology suggests  a protective effect of childhood helminth exposure on IBD risk, but what about controlled trials in adults? In one case , patients with Crohn’s disease who were exposed to hookworms had less reactivity to the parasites than controls without Crohn’s; the hookworms were less of an “immune insult,” and presumably more of an aid.
Allergies: A number of helminth species down-regulate allergic responses to otherwise harmless antigens  by modulating the immune system, but some species appear to have the opposite effect  (common roundworm infection for example has been associated with asthma and shrimp allergy ). The children of mothers given antihelminthic drugs during pregnancy tend to have more infant eczema , which may presage future allergies.
Asthma: One study  found that hookworm infection mildly improved airway responsiveness in asthmatic patients, with no effect on other parameters of asthma, but the dose was small – just 10 hookworm larvae. The most common dosage for hookworm therapy is around 35 larvae, so it’s possible the dosage was just too low.
Multiple sclerosis: Via a retinoic acid-dependent pathway (eat your vitamin A!), helminths have been shown to modulate the immune response in multiple sclerosis patients . Those who were infected had better outcomes than those who were not.
Celiac disease: Human hookworm infection suppresses the inflammatory immune response to gluten  normally seen in patients with celiac. It even improves mucosal immunity and may help heal  celiac patients, not just suppress their response. However, another study  using an oral wheat challenge (equivalent to 16 grams of gluten a day, which is a fairly high dose) in celiacs found no benefit to hookworm infection.
Helminths may also be a potential therapy for atherosclerosis , joint inflammation , autism , and type 1 diabetes (PDF , if you catch it before it develops). They seem to have a favorable impact on gut microbes, restoring the mucosal lining and rebalancing the floral communities to be less inflammatory in macaques with diarrhea , so there’s probably a role for general immune and digestive health as well.
Okay, that’s cool and all, but we’re still dealing with worms wriggling around in your gut. There’s little else more unnerving and repulsive than the thought of hookworms setting up shop in and gnawing on your small intestinal lining. And there are dangers to helminths, particularly in developing countries where people tend to be malnourished, absent access to medical care, and carry large parasite loads. Most intestinal worms consume blood. Get enough of them lodged in there and you can end up with anemia , malnutrition, growth deficiencies – especially if you’re a young child.
But anemia only occurs when people are getting reinfected due to frequent contact with parasite-laden fecal matter in the environment and the parasite loads get out of hand. In a controlled, clinical setting where infection is carefully curated (to prevent reinfection) and the patients have access to plenty of nutritious food and medical care, it’s far safer. As it stands now, helminths must satisify certain safety and efficacy parameters before being considered for therapy. Qualifying worms:
- should not have the potential to cause disease in man at therapeutic doses
- should not be able to reproduce in a host, thus allowing control of dose
- should not be a potential vector for other parasites, viruses, or bacteria
- should not be easily transmissible from the host to other people
- should be compatible with a patient’s existing medication
- should have a significant period of residence in the host
- must be easily eradicated from the host, if required
The majority of clinical trials of helminthic therapy have a relative paucity of adverse reactions. Diarrhea, stomach upset, and skin irritation are the most common side effects, but usually only for the first few days and not in everyone. If it were to get out of hand, anti-parasite drugs are effective, fast-acting, and safe.
Grok  definitely had parasites, but he probably wasn’t loaded to the gills, instead carrying just a few select species. The most prevalent helminth among a group like the San Bushmen, for example, is necator americanus, the human hookworm (PDF ) species thought to have the most therapeutic potential. The largest parasite loads are seen in agricultural communities whose inhabitants have close, constant contact with animals (and their waste) and each other (and their waste). Hunter-gatherers had (and have) higher parasite loads than modern industrialized populations, but not as high as agriculturalists because they were steadily on the move and switched locations when parasites and parasite-laden feces became a problem. When hunter-gatherers hunker down and become sedentary, parasite infections skyrocket .
Pig whipworm is a current favorite among helminth enthusiasts, since it’s non-native to humans, it doesn’t survive for long and it doesn’t reproduce in the human host. This prevents overpopulation, but it also necessitates frequent re-dosing of eggs to maintain treatment, which gets very expensive. Treatment with pig whipworm can easily hit thousands of dollars per month.
Necator americanus, the human hookworm, appears to have the most potential against autoimmune diseases. It’s native to humans, cost-effective (lives for 3-5 years inside the host after a one-time infection), and sheds its eggs in the feces. As long as your feces are going into a toilet and not your backyard, there’s no chance of increasing your parasite load from reinfection.
This information isn’t easily actionable, not like information about exercise or diet or sleep is actionable. First of all, worms are scary. Way scarier than trying squats  or eating liver  or setting a strict bedtime . Parasites can be problematic, and many of us really have no way of safely inoculating ourselves. Which ones? Where do we find them? What if we mess up and get something really pathogenic? After all, the people who do carry parasite burdens generally don’t go about looking for them; they just pick them up through incidental, everyday contact. Clinical trials are underway, and I’d imagine the FDA will be getting involved soon enough.
If you are interested in helminthic therapy, you’ll probably have to handle things yourself. Here are a few ways to learn more, but please be advised that I don’t recommend, exactly, you do any of the following, and suggest you consult with a doctor before proceeding:
You could join the helminthic therapy group  on Facebook and/or the Yahoo mailing list , where you’ll gain access to plenty of likeminded souls with extensive personal experience with worm therapy, as well as helpful resources, links, and advice. Brave souls are even doing some clandestine unregulated worm trading.
Nearly everyone but US residents can have worms shipped to them by Autoimmune Therapies .
US residents will have to truck it down to Worm Therapy , which operates out of Tijuana, Mexico, just across the border from San Diego. They offer hookworm and whipworm. Another option is to contact Coronado Biosciences , a company that’s currently running US trials  for pig whipworm in Crohn’s disease in a number of cities across the country .
Also, mention it to your physician! He or she may balk or cringe or shower you with condescension, but it’s a good idea to be under medical supervision when infecting oneself with helminthic worms. And hey, if it works – and there’s a good chance it might – you very well could change an influential mind.
Is there a role for helminths in general health and immunity? Probably. But I’d wait for more research to take place before having nematode eggs and bacon for breakfast. If you’re suffering from any of the diseases shown to be modulated or improved by helminthic therapy, however, it might be worth researching.
What about you guys? Grossed out? Intrigued? About to book a trip to Cameroon? Let’s hear your reactions in the comment section!