Parasitic Worm May Increase Women’s Fertility

Tsimane women in Bolivia have an average of nine children in the family. Immune systems of women changed naturally during pregnancy, so they didn’t reject foetus, he said.

The idea of becoming infected with a parasitic worm is enough to make most people’s skin crawl, but a new study says that giant roundworms have an unexpected side-effect – they can make women more fertile. Meanwhile, the ones who had a hookworm were more likely to have three fewer kids than uninfected women.

The researchers also noted that the women infected with the roundworm species have shortened intervals between births and have earlier first pregnancies.

Another worm, the hookworm, was found in the study to lead to fewer children across a woman’s lifetime – probably because this particular parasite suppresses the immune system, rather than enhances it.

The scientists studied nine years’ worth of data from 986 women from indigenous Tsimane women living in the Amazon rainforest in Bolivia.

“These opposing effects are likely due to helminth infection affecting the immune system, which in turn affects the likelihood of conception”, Blackwell said. This means they double in size every 17 or so years. Such infections, he added, may significantly affect the demographics in developing countries. “Further, these results may also have implications for fertility in developed populations, where many fertility problems are connected to autoimmune disorders”.

“UCSB anthropology professor Michael Gurven, a study co-author, said that while they are yet to know the exact mechanism behind the findings, they suggest that” immune modulation, through worms thriving in the intestines, can greatly affect the body. The latter results were consistent for young women.

Roundworm infection reduced the length of intervals between births over the course of reproductive lifetime, the results revealed, while hookworm infection increased birth intervals.

Rick Maizels, a parasite immunologist from the University of Edinburgh, said: “This is a very original study”.

“I think it’s going to spark a lot of other investigations”.

Intestinal worms, or soil-transmitted helminths (STH), are caused by a group of parasitic worms, most commonly hookworm, roundworm (ascariasis) and whipworm (trichuriasis) that are either transmitted through contaminated soil or by ingesting parasite eggs, according to The End Fund.