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
In medicine, inflammatory bowel disease (IBD) refers to a group of inflammatory conditions of the colon and small intestine. There are two main forms:
When people from developing tropical countries immigrate to cleaner, temperate ones, they seem to have an even greater propensity to develop IBD than natives. 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.
Parasites—Now and Then
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 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,
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.
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]:
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, 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.
Joel Weistock 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. And no vaccination or antimicrobial would fix it. Addressing the problem would require an ecosystem restoration of sorts— such as worm therapy. 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.