In a forum of smart folks I’m part of, a science fictional conversation came up: if we could terraform another planet, picking and choosing what species we’d put on it, why would we bother with parasites? People bandied around things they’d love to do without, like mosquitoes, poison ivy, ticks, fleas, and various disease-causing bacteria. It was immediately pointed out that nature abhors a vacuum, and heretofore benign species would evolve to fill those niches. While we humans don’t see the use for something like an ectoparasite that bites us and eats from the blood we spent all that time and energy making, there are ecological roles for them. Mosquitoes, for instance, provide sustenance for bats and dragonflies, both of which are amazing creatures we’d like to encourage and have around. (conversely, if you are bothered by mosquitoes, consider attracting their predators by doing things like installing bat houses).
But what about endoparasites, the little creepy-crawlies that infect our guts and steal our nutrients? What good can they possibly do for us?
It turns out, when our bodies are fighting an external foe, they have less energy for turning on their own cells with the remorseless hunter-killers of the immune system. It has become well established that we can use parasitic infection to reverse severe allergic and autoimmune reactions. It become akin to that old chestnut, of three guys working themselves up to a fight, and then one takes a step back and says ‘let’s you and him fight!’ while he stays safely out of it. Only two of those guys share a body. The immune system, when it’s all worked up and looking to do battle, can lose the ability to tell the difference between self and non-self cells, leading to inflammation and symptoms that resemble those of a disease, but are entirely self-inflicted. The addition of a parasite, an external foe, keeps the immune system focused away from the self-cells.
In 2012, Joel Weinstock published a paper in Nature, discussing the thoughts behind using helminths (parasitic flukes) as a treatment for autoimmune disorders such as IBS and Crohn’s. While there are significant health hazards associated with parasitic infection, there may be less of a risk in using them to draw off the immune system from attacking an individual’s body. He and his team went on to infect humans with a parasite known to have a short lifespan in human guts, and to not cause symptoms. They saw statistically significant reports of lessening of symptoms (of acute autoimmune bowel disorders) and even complete remission. It seems clear that yes, worms can serve as scapegoats for the human immune system.
Studies done by P’ng Loke and his team on a patient suffering from ulcerative colitis who had been self-infecting with a worm normally found in pigs showed that genes were affected by the presence of the parasite, leading to greater healing of the gut and production of mucus that protected it (1). The research being done by Weinstock and the Loke team are based on the Hygiene Hypothesis, which was postulated in 1989 by David Strachan, and states that in effect, clean living has led to an increase in allergic reactions and autoimmune disorders. As we have cleaned up our living spaces, exposures to pathogens, and even our environment, our bodies have turned inward and on themselves. Without the external enemy, it becomes ‘Let’s you and me fight.’
Initially, the focus of research was on T-helper cells, which are implicated in diabetes, asthma, and bowel disorders. As time went on, that focus showed that it was more likely a complex balance between T-regulatory cells and the Th cells that was leading to the affects on the human body of it’s own immune system’s attacks (2).
…the risk of developing allergies is not necessarily caused by a lack of bugs and parasites in the environment per se, but rather by a lack of certain organisms that have, over the course of evolution, trained our immune system to be more tolerant
So the equation goes from a simple 3-1=2, to something more resembling a polynomial equation, or perhaps calculus, where we can calculate the results as the limits approach zero. You can’t divide by zero, we all know that. You can get really, really close to zero, and that seems to be what is happening in the human body. Without the tutorial effect of microbial presence to ‘teach’ the immune system not to react, Graham Rook speculates that the immune system simply goes into overdrive and starts reacting to… everything.
“People get the immune system the wrong way around. We’re so focused on the immune system responding to things, that we forget that 99.999% of the time, its job is to not respond to things. There’s you and your breakfast and your gut, for a start. That’s a lot of stuff to not respond to.”
So why wouldn’t we want to run out and buy a bunch of worm eggs, if we have an autoimmune disorder? Firstly, the studies are being done with parasitic worms that are a very particular species which cannot survive in the human body for long, so cannot migrate into organs they shouldn’t be in – like the brain, and liver, and eyes. If you order a capsule of worm eggs over the internet, how do you know what you’re getting? Are you willing to risk blindness, insanity, and death just to possibly ease your symptoms? Clinical trials and FDA regulations do exist for a reason, as much as the cost and delay may chafe. Studies have not always been positive, some showing no results at all. Others are ongoing, like one in Australia studying the effects of helminthic infection on Celiac disease, which is initially quite promising. But in the meantime, while the system is slowly processing data, a black market of worms has sprung up, with desperate people paying thousands of dollars to dose themselves with parasites. It might not be safe, or even scientific at this point, but it is human nature to try anything to ease pain. And the human brain, being an amazing organism, can even respond to the desires of the soul with the placebo effect. Only time will tell if the stories of those who swear by a return to an older, darker time full of worms are based in wishful thinking, or in reality.