Hiding, a "nitty gritty" comb, loads of conditioner, a lot of time to do it painstakingly slowly, and repeat every day for a week is supposed to work.
Or ask the pharmacist for what she can use for a two year old. I last had them when I was pregnant with the eldest (his father caught them at the job centre, ugh!) and there was only one I could use while pregnant, can't remember the name of it but basically an expensive version of the comb & conditioner treatment.
it did work, though!
tea tree oil shampoo and conditioner for the kids (or vosene do a nit prevention all-in-one) once they've got rid of them, it's supposed to help. And smother their hair in products to go to school/nursery, the nits can't cling to the hair if it's covered in gel/spray etc.
I'm a hypocrite, because I'm going to say that long hair should be tied up for school and playdates, yet my 4 year old won't let me put his up for school! ugh, I'm itching now thinking about it.
Oh, and any adults they tend to hug should be de-nitted too.