Why can't I get rid of them? My son seems to permanently have them. I treat with Ovex. He is good at hand washing. Short nails. Shower every morning. Bed sheets washed regularly. It's like every three months I find them again around his bum. Is it worth asking the GP if we can do an extended dose? I've never had symptoms and have always treated myself at the same time, but really just want them gone! They are freaky little things.