Head lice are wingless insects that live on people's heads and feed on their blood. Head lice are extremely contagious. Close contact or sharing personal belongings, such as hats or hairbrushes, puts people at risk. Children ages 3-11 and their families get head lice most often. Personal hygiene has nothing to do with getting head lice. source
Having head lice is not a serious medical condition. They do not spread disease. The symptoms are:
An adult is called a louse and is about the size of a sesame seed. The eggs, called nits, are even smaller - almost like a dandruff flake. Lice and nits are easiest to detect at the neckline and behind the ears.
Lice infestations are spread most commonly by close person-to-person contact. Dogs, cats, and other pets do not play a role in the transmission of human lice. Lice move by crawling; they cannot hop or fly. Lice are fragile, and the chances of being passed on hats and combs are low. Stray lice that fall off a head are either injured or dying and incapable of causing a new infestation. Although schools, day care centers, etc. are often blamed for head lice outbreaks, it is the family unit that maintains cases leading to outbreaks in schools.
Both over-the-counter and prescription medications are available for treatment of lice infestations. Follow instructions and avoid over treatment.
The Department of Health has developed a policy that provides head lice guidance for schools and school administrators.