Laptop sleeve to keep clean?

I have a laptop that's a year old. I left my laptop on a shelf under my desk in my room before I left for christmas vacation. When I came back, I had lots of tiny white mites (size of a small dot) or tiny white bugs crawling all over the keyboard. I cleaned, vaccumed the keyboard, and wiped out my laptop. I also placed it inside a plastic bag and sealed it to kill off the tiny white mites. So far, it appears be gone for now. What can I do to prevent this from happening again? What would you recommend for a college student? Would a laptop sleeve be good?