The worm wriggles out to mate and its eggs are eaten by small water worms that

The worm then wriggles out to mate and its eggs get eaten by little water insects that mature, colonize land, and are, in turn, eaten by new crickets. And thus, the Gordian worm lives on. And here's the rabies virus, another mind-altering parasite. This virus infects mammals, often dogs, and travels up the animal's nerves to its brain where it causes inflammation that eventually kills the host.