Intestinal parasites help you get pregnant 28.11.2015

It may sound strange, to put it mildly, but intestinal parasitic worms and the embryo growing in the womb have something in common. They have to solve one problem: how to convince the immunity of the host / mother so that he does not attack them. The immune system perceives both the child and the worm as strangers that need to be expelled from the body. In the course of evolution, of course, certain tricks have developed that allow one to “negotiate” with immunity. However, what is interesting here is that parasitic worms can use mechanisms similar to those that are built into the program of embryonic development: for example, both the fetus and the worm stimulate the activity of regulatory T cells, whose job is to suppress immune attacks.

So you can understand the logic of researchers from the University of California at Santa Barbara, who decided to test whether intestinal parasites help women get pregnant. After all, if a woman has such a parasite, he can prepare immunity in advance for the appearance of the embryo. Aaron Blackwell and his colleagues headed to the Amazonian forests in Bolivia, where the Chimane Indians live. By the way, they often become the object of attention of anthropologists due to their "natural" way of life - the Chimans live by hunting and fishing, growing rice and bananas, and are not too affected by civilization.

As it turned out, quite a lot of Chimane people are infected with parasitic worms: 15-20% of them serve as hosts for human roundworms (Ascaris lumbricoides), 56% have hookworms, Ancylostoma duodenale and Necator americanus. The lifestyle of roundworms and hookworms is different: if the former simply eat from the "master's table", assimilating those nutrients that got into the intestines with food, then the latter behave like real vampires, sucking blood from the intestinal wall. The Chimane women did not know that they had parasites inside them, but this definitely affected their condition.

Those with hookworms had a lower body mass index (meaning they weighed less for their height than their counterparts without parasites), had lower hemoglobin levels, and had an average of three fewer children over their lifetime. than in healthy women. Those infected with A. duodenale and N. americanus had their first child later than the rest, and they had an increased time between pregnancies.

But with roundworms, everything was different - they just stimulated fertility, and their effect was the opposite of that demonstrated by hookworms: with A. lumbricoides, a woman gave birth to her first child earlier, and the time between pregnancies decreased, so in total she had in a lifetime, it turned out to be two more children than those who were not infected. Obviously, roundworms suppress the inflammatory immune response in such a way that they facilitate the conception and implantation of the embryo in the uterus. Hookworms, on the other hand, probably harm the body so much that it neutralizes any positive effect from their presence. The specific physiological mechanisms here will become clear once the authors analyze blood samples from Chimane women for immune changes in the presence of intestinal parasites.

It is known that a successful pregnancy depends on the bacterial microflora, but this has not yet been thought about worms. On the other hand, we know that parasitic worms, by interacting with the host's immune system, help to alleviate allergic and autoimmune diseases (in particular, a few months ago we wrote about how intestinal parasites protect the brain of hosts). It is unlikely that roundworm will be used as a remedy for infertility, however, having carefully studied them, we ourselves, without the help of parasites, could trigger the same mechanisms of regulation of the immune system that are used by worms and which, as a result, facilitate conception.