Parasitic worms increase female fertility?

Can parasitic worms increase female fertility?  Accordingly to what parasitic worm is a woman’s digestive system infected with, she can conceive a child more or less easily. That is the unexpected conclusion of a quite unusual research study who studied a Bolivian tribe of the Amazon called Tsimane.

Bolivian Tsimane

The Tsimane women have been ranked among the most fertile women in the world.

The idea of conducting this piece of research came from a team member who had begun trying to conceive while working in Bolivia. The fact she conceived rather quickly got her wondering whether there was an environmental factor that made her more fertile and as it turned out…it was a worm!

The biologist who led the study, Aaron Blackwell of the University of California, Santa Barbara, and his team had been gathering data from about a thousand Tsimane women for nine years. The study results were published in ‘’Science’’.

The Tsimane women have been ranked among the most fertile women in the world, having 10 children each on average,  but it appears that some of them are even more fertile compared to others of their tribe.

Study researchers presented evidence that women infected with a specific kind of parasitic worm, a type of hookworm, tend to conceive their first child later in life, have long gaps between their children and have less children in overall. On the contrary, women infected with another type of helminth have birth of their first baby earlier and tend to have more children.

Scientist concluded that the one type of helminth increases female fertility while the other hinders it. The cause of this fertility effect is unknown; however, Blackwell’s theory is that this fertility effect’’ could be related to the balance immune responses that the different parasites induce’’.

70% of the  (roughly 16.000 people) has been infected by parasitic worms without taking notice. Women infected with the roundworm (which could grow up to 36 cm) have 3 children more than those not infected. On the other hand, women with the hookworm have 3 children less.

It is estimated that approximately 800 million people have been infected by either hookworm or roundworm globally. Consequently, it is possible that such parasitic infections may play a role to global demography if they indeed have such a major effect on female fertility.

Did this study make you reconsider your opinion about worms? 

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