There is no evidence to suggest that head lice makes people sick. However, the itching caused by lice leads to scratching, which can lead to scalp infections.
Lice are parasites that live on the scalp and on hair strands. They eat small amounts of blood and stick to the hair shaft using their feet. Each louse can live on the hair for up to 30 days and it doesn't take long for them to begin laying eggs.
Lice eggs are laid at the top of the head, near the scalp and on the nape of the neck. They range in color from white to brown and a female louse can lay up to 10 eggs per day.