Apr 14, 2025 04:11 PM
https://www.mcgill.ca/oss/article/critic...s-immunity
EXCERPTS: . . . Deliberately infecting yourself with parasites appears imbecilic on its surface. After all, we fund programs to deworm people in the Global South because worms can cause disease. We are not talking about earthworms, here, but helminths, tiny worms that have evolved to survive inside of a host—either us or some other animal, which suffers the consequences while the worm thrives. A helminth infection can lead to anemia, hypertension, malnutrition, and gut issues. But worms are not necessarily bad, and here is where we arrive at the crux of the argument in their favour: the hygiene hypothesis.
In a nutshell, our industrialized world is too clean. Through vaccination, pasteurization, cold chain, and overall cleaning and disinfection practices, we have kept many microorganisms at bay. Meanwhile, we have seen a pronounced rise in diseases with ties to our immune system: allergies, asthma, various skin conditions, type 1 diabetes, lupus, Crohn’s disease, ulcerative colitis, and rheumatoid arthritis. Many of these are autoimmune conditions where our immune system rebels against a molecule that belongs to our body, like an army attacking its own citizens. Better diagnosis and increased medical access help explain why some of these diseases are on the rise in Westernized nations, but it’s not enough.
The hygiene hypothesis states that increased sanitation caused this rise, or is at the very least one important cause of it. Up until recently, the human race was full of parasites. It was the norm, and we contracted them through farming, hunting, working the land, eating tainted food, and drinking polluted water. This means that our immune system evolved inside bodies that were infected by helminths. The theory goes that, when you remove the worm—a so-called “old friend” of the human body—the immune system is out of balance. It malfunctions. (This theory is a bit too neat: many pieces of evidence contradict or bring nuance to it, as Dr. Christopher Labos and I discussed here.)
Scientists have tried to explain how mechanistically this would happen. [...] The goal of helminthic therapy is to reintroduce the worm into the body in an attempt to treat allergies or an autoimmune condition. Not all helminths are created equal, though; the ideal worm would not cause any disease, would not multiply inside the body or colonize multiple organs. It wouldn’t spread to other people or cause symptoms in its host. It would resist common medications but be killed with antiparasitic drugs. Finding such a hero worm has not been easy, but a few candidates have made it to the top of the list.
The two biggest players in this field are the human hookworm (Necator americanus) and the eggs of the porcine whipworm (Trichuris suis ova), with the latter receiving approval by the U.S. Food and Drug Administration to be used in human research. The evidence for helminthic therapy in animal models—meaning rats and mice which are bred to express diseases similar to the ones we want to treat in humans—has been encouraging, often because scientists use a lot of worms to create an effect on the immune system. The problem is that we are not large mice... (MORE - missing details)
EXCERPTS: . . . Deliberately infecting yourself with parasites appears imbecilic on its surface. After all, we fund programs to deworm people in the Global South because worms can cause disease. We are not talking about earthworms, here, but helminths, tiny worms that have evolved to survive inside of a host—either us or some other animal, which suffers the consequences while the worm thrives. A helminth infection can lead to anemia, hypertension, malnutrition, and gut issues. But worms are not necessarily bad, and here is where we arrive at the crux of the argument in their favour: the hygiene hypothesis.
In a nutshell, our industrialized world is too clean. Through vaccination, pasteurization, cold chain, and overall cleaning and disinfection practices, we have kept many microorganisms at bay. Meanwhile, we have seen a pronounced rise in diseases with ties to our immune system: allergies, asthma, various skin conditions, type 1 diabetes, lupus, Crohn’s disease, ulcerative colitis, and rheumatoid arthritis. Many of these are autoimmune conditions where our immune system rebels against a molecule that belongs to our body, like an army attacking its own citizens. Better diagnosis and increased medical access help explain why some of these diseases are on the rise in Westernized nations, but it’s not enough.
The hygiene hypothesis states that increased sanitation caused this rise, or is at the very least one important cause of it. Up until recently, the human race was full of parasites. It was the norm, and we contracted them through farming, hunting, working the land, eating tainted food, and drinking polluted water. This means that our immune system evolved inside bodies that were infected by helminths. The theory goes that, when you remove the worm—a so-called “old friend” of the human body—the immune system is out of balance. It malfunctions. (This theory is a bit too neat: many pieces of evidence contradict or bring nuance to it, as Dr. Christopher Labos and I discussed here.)
Scientists have tried to explain how mechanistically this would happen. [...] The goal of helminthic therapy is to reintroduce the worm into the body in an attempt to treat allergies or an autoimmune condition. Not all helminths are created equal, though; the ideal worm would not cause any disease, would not multiply inside the body or colonize multiple organs. It wouldn’t spread to other people or cause symptoms in its host. It would resist common medications but be killed with antiparasitic drugs. Finding such a hero worm has not been easy, but a few candidates have made it to the top of the list.
The two biggest players in this field are the human hookworm (Necator americanus) and the eggs of the porcine whipworm (Trichuris suis ova), with the latter receiving approval by the U.S. Food and Drug Administration to be used in human research. The evidence for helminthic therapy in animal models—meaning rats and mice which are bred to express diseases similar to the ones we want to treat in humans—has been encouraging, often because scientists use a lot of worms to create an effect on the immune system. The problem is that we are not large mice... (MORE - missing details)