I deworm all incoming mice. I use ivermectin (also used to treat mice) or Stronghold (selemectine, this is a bit safer than ivermectin). In the past I've used levamisole, but than you have to treat them twice.
Because I'm a vetstudent, I can check for worms myself. I do routine check-ups every 2 months. I've never had to treat them, since I started deworming all incoming mice.