Parasite avoidance is a factor, but mostly in the inhibition of cannibalism.

Cats are far from apex predators. They are prey to birds of prey, canids and even bigger mustellids like badgers and wolverines. But birds, like the eurasian eagle-owl and canids like coyotes are their main concern.

And we can clearly see the prey behavior deeply ingrained in our very cautious, flighty friends.