Parasitic insects that live on hair.

Infestation with head lice, also called pediculosis, is a common occurence in schools and day care centers. Head lice are parasitic insects that live on hair. The adults feed on blood from the scalp, causing intense itching, and lay their eggs (nits) on the hair shaft. Lice do not fly or hop like fleas, but they are quite easily passed from child to child. Playmates can pass them along through close physical contact, sharing hats or hair brushes, or lying on bedding or furniture on which lice-infested hair has fallen. If a few children in a school group have head lice, an epidemic may quickly build. Treatment is not difficult, but it may be drawn out if not all the nits are caught, or if the child is reinfested.

Symptoms of head lice include intense itching of the scalp, but...