Programs that conduct routine classroom "head checks" to identify individual cases of head lice before the lice are spread to others. Head lice are transmitted from person to person through close body contact, or through sharing combs, brushes or hats and other headgear. Children with evidence of louse infection (nits and/or crawling lice) are usually sent home after parents have been notified along with louse control instructions. Infested children are generally not readmitted until proper treatment has been initiated. Lice do not infest classrooms, carpets and chairs as they die within 24-48 hours of separation from the warm and humid body environment, so spraying classrooms or areas of the home is not a useful control strategy.