My DD had them a couple of times when she was in Elementary school , what a pain in the rear!
I did find this great shampoo that kills them , it is from the health food store , all natural!
Its called Dessert Essence Therapeutic Treatment Shampoo, with Eco-Harvest Tea Tree Oil ,Blue Cypress and Eucalyptis. For problamatic scalp conditions &head lice. Buy both the Shampoo and the Conditioner.Follow directions on the bottle . I used to use it at least once a week as a preventative when my kids were younger. it really works without all the harsh poisons.
Good Luck!
Also another product for bedding and furniture you just spray it on , by a company called Pleasant ;Lice Free Lice Control Spray. No pesticides safe to use around animals and humans . it smells like cedar .