Changing Litter Box. It holds the waste, and it keeps. Cats will often stop using a box if they feel it is.
The concern here is toxoplasmosis, a parasitic infection that can be transmitted through cat poop (such as in kitty litter or outdoor soil where cats have defecated). Start by filling your litter box up with about an inch and a half of your new litter. Cats appreciate good litter habits, and will usually let you know if.