Lice are small, grayish-brown insects that live on humans. Lice bite through the skin and live on the blood of the host, another name for the infected person. Female lice lay eggs -- called nits -- that firmly attach to hair shafts. Head lice live on the scalp and are common among school children. Lice also can be found on the body (body lice) or in the pubic region (pubic lice).
Head lice are spread by direct head to head contact and by sharing items including combs, brushes, scarves, and hats with an infected person. Pubic lice (crabs) are spread by having close physical contact with someone who has them. They are most often spread by sexual contact, but they can also be spread by having contact with infested clothing, bed linens, and toilet seats.
Lice infestation has nothing to do with poor hygiene. Lice can also affect people of all social classes.
What Are the Symptoms of Lice?
Bites from lice can cause intense itching and irritation of the scalp or other area of the body where lice are present. Symptoms may not occur until at least two months after the lice begin living on the body. In cases of head lice, a person may develop a rash on the nape of the neck.
What Is the Treatment for Lice?
Insecticides can be used to treat head lice by killing them. These products are available in lotion and shampoo form and can be purchased over-the-counter or with a prescription. Some studies suggest that pyrethroid insecticides (such as allethrin, resmethrin, permethrin, cyfluthrin, or esfenvalerate) can affect cognitive development in children. More research is needed.
Lice eggs (nits) can be more difficult to treat because the insecticide lotions do not penetrate the eggshell to get in to the developing louse. Therefore, it may be necessary to repeat the treatment after seven days to kill lice emerging from any eggs that survived the first application. Using a nit comb can help to get rid of nits.