Maybe this is a stupid question, but how do you know when your DCs have worms?? My youngest has just started Reception and has been scratching his bottom a lot which has made me a bit suspicious but could be nothing I suppose..
Boys - you need to get your DS to keel down and then curl into a ball with his bottom in the air, so you can see his, er, bumhole (for wnat of a better word!) - you can often see the little blighters wriggling (v small white). Or you could check his poo. Howefver, if he is itching a LOT, I'd just give him some medicine (can buy over counter) and let teachers know you suspect he has had them.
One dose gets rid of them IIRC.
seeker - I just made sure all teh bedding and towels were washed, I didn't frantically wash every single thing in the house and we didn't get them back.