The best mattress cover is a zippered encasement that is designed specifically to assist with the control of these pests. A zippered encasement will help make the process much easier for the extermination. If you aren't infested, it can assist you in keeping your home free of them. It is also important to remember to only consider the box spring and mattress covers that are "scientifically proven" to be effective against these insects. This ensures that tests have been done to prove the cover is bug and bite proof.
It is also an ideal way to start conquering a current infestation. If the infestation is severe, consider the use of mattress protective covers in combination with sprays, traps and powders.