When mice become infected by eating cat feces, the parasite alters the chemistry in their brains

When a rat gets infected by eating cat feces, the parasite changes chemical levels in the rat's brain, making it less cautious around the hungry felines,
maybe even attracted to them. This makes them easy prey, so these infected rodents get eaten and pass the parasite on. Mind control successful.
There's even evidence that the parasite affects human behavior. In most cases, we don't completely understand how these parasites manage their feats of behavior modification.