The thing with Evil is that it is self destructive. This is actually a problem with easy simple solutions. Keep the beasts quarantined. Keep them away from borders. Remove all favorable treatment and welfare. If they come in, they pay their way. If they can't prove themselves to be a positive contribution, deport them. Keep the border tough and secure. A country that has become prosperous can only fall from within. No one can help you or hurt you more than your own self. Individuals need to take charge and stand up.
All you have to do is remove welfare and put some guns around the borders. The bloodsuckers will take the path of least resistance and go somewhere else and eventualy run out of prosperity and remove themselves from human civilization like the Amazonian/African tribes they mostly resemble.