Slowly, ever so slowly, your body becomes filled with so many cats that you become a horrifying abomination of flesh, fur, and kitten heads, slowly purring whilst you pulsate helplessly upon the floor as a swollen mass of cuteness. People will often come to poke you, but you can't perform any action which might impede them, so you are left to suffer.
Some people do, but then the body just grows a new head. You have to put a patch over them to shrink the whole cat, then they can be lifted up out of the cavity. You'll have to cover that over to prevent reinfestation while your flesh fills back in.
I don't plan on Guts to always have a visible tapeworm...it'd make him just one detail too busy. In fact, I was going to take it out of the first and third panels, it'd just be funny for close-up shots.