We live in the country, so we go through the mouse thing every fall when the farmers cut down the crops, until the spring, when the mice go back outside for safe shelter.
The best methods I have found to get rid of the mice are 1) get a cat, if you can. They catch the mice and bring them to you, so you can toss them out the door. Plus, the cats will typically hang out at the mice's point of entry, so you can attempt to seal it and alleviate the problem. 2) At Walmart, you can buy humane mouse traps. Basically, it's a dark gray, see-through rectangular box with a one way door on the end. Mice can go in, but they can't get out. We put a small dollop of peanut butter just inside the little door and hide these traps, and we never fail to find one or two mice in each one by morning. They're still alive, no poisons or extermination foggers are being used, and you're child and you are safe. You can drop the mice back outside (away from the apartment building), and go on with your life.
Hope I've helped. At least summer is coming, so you shouldn't see too many more mice regardless of your attempts to rid your apartment of them. Good luck!