You can do one of two things to the bedding to clear it of parasites before giving it to them....1.) bake it or 2.) freeze it.
1.) Lay out the bedding in a cookie pan, evenly layered. Pre-heat your oven to 200 degrees. Let it bake for a couple of hours. Bring out and let cool.
2.) this only works in a sub-zero/deep freezer...for *at least* 24 hours.
Second...
To treat mice....if you are in the USA...go to your local feed store (for horses and cattle and other livestock). Find something called: "Iver-On"...it's in a purple and white box.
http://www.jefferslivestock.com/ssc/pro ... id=0026251
Get the smallest bottle. Use 5 parts water and 1 par Iver-On. Load it into a common spray-bottle....or into a syringe. About .01 ml into the syringe (the spray bottle delivers about this amount) and either spray or drop it directly onto your mouse in between their shoulders. Do not get it into eyes or open wounds. Treat once every 7 days for three weeks, then take a break for two weeks. After two weeks, treat again every 7 days for another three weeks.
I also lightly spray bedding and toys during treatment.
Iver-On has an extremely long shelf life, and is even safe enough to use on pinkies. I treat every new mouse with it, as it ois also a great preventative. If you are not sure how to mix it, ask a vet to do it for you.