Horsehair worms can grow up to a foot long and manipulate host insects — and sometimes show up in toilets — but are harmless ...

Horsehair worms, also called Gordian worms ... according to the University of Kentucky. They do not infect humans, livestock or pets, and are considered harmless. The worms also live inside ...

Genetic research from Texas Biomed shows human and cattle schistosome parasites are not currently interbreeding, easing concerns over cross-species infection risks.