Empty trap

It seems we have a rat or two living somewhere nearby, not at all shy they were dancing round the garden like performers in the Pied Piper. We have a trap as it's not the first time we have had this problem but the rat ( or rats ) seem very smart and able to easily remove the bait without springing the trap. I don't really like to kill them but I also know that they can bring a lot of bad bacteria and germs which I don't want to encounter