As far as I know mite from rodents are different then snake mites. Can mites kill a snake? Yes they can they can stress them out and keep them from eatting, and they also are sucking blood from the snake making it very dehydrated. Mites are something that you need to stop and can not let continue. As far as the snake feels think of it like when you were a kid and had lice, I am sure we have all gone through that at one point in time and it sucks.
What to do:
First of all the hydration of the snake is very important so get a container that the snake can lay out in and fill it half way up the snakes body with room temp water. Make sure it is not to hot and not to cold. When you put the snake in the water if it starts freaking out trying to get out your temps are most likely off and need changed prior to leaving it in there. Give it at least 30 min soak every day. Also make sure your snake doesn't have to swim to stay a float.
As far as the cage is concerned if you have a fish tank cage, stick it in the bath tub and fill it to the rim with water, let is soak for a half hour. Then mix water with a very small amout of bleach (1 cap per gal-2 gal) and wipe down the cage, making sure to get the conners. Then rinse out good. Us paper towels as bedding for the time.
Repeat both of these methods daily or at least every other day and you should knock out your mites in about 2 weeks. Also remember just because you don't see them doesn't mean they are gone so if you don't see them after a week do not stop go the full two weeks. Also keep an eye on the water as mites cannot swim and you should see them laying at the bottom after the snake soaks.
matt