Regardless of what it is you have in your freezer, disease and bacteria cannot be transferred in a frozen state. Even if the parasites remain alive(which some do), they are frozen in a dormant state and cannot transfer from one frozen food to another. Just make sure your mice are in seperate baggis or packaging and it should be no problem...
FWIW--I'm a sinlge dad, so my freezer is chock full of TV dinners, frozen pizza, bread, meats and mice...