Common Illnesses & Injuries

Head Lice

Overview

The medical name for head lice is Pediculus humanus capitis. They are parasitic insects found on the heads of people. They do not cause disease and they are not particularly serious medically, but school nurses who understand how creepy they are to parents treat them as serious business. Lice do not indicate that a child or family is not clean. Regular shampoos and soap don’t phase them. They don’t live on pets. They only like humans.

Preschool and elementary school children (ages three to ten), and their families are infested most often. Girls get head lice more often than boys, women more than men. In the United States, African-Americans rarely get head lice. They spread like wildfire in schools, slumber parties, sports activities, at camp, on at the playground. Most people who have them don’t know it unless they are screened.

There are three forms of lice: the nit, the nymph, and the adult.

Nit: Nits are head lice eggs. They are hard to see and are often confused for dandruff or hair spray droplets. Nits are found firmly attached to the hair shaft. They are oval and usually yellow to white. Nits take about one week to hatch.

Nymph: The nit hatches into a baby louse called a nymph. It looks like an adult head louse, but is smaller. Nymphs mature into adults about seven days after hatching. To live, the nymph must feed on blood.

Adult: The adult louse is about the size of a sesame seed, has six legs, and is tan to grayish-white. In persons with dark hair, the adult louse will look darker. Females lay nits; they are usually larger than males. Adult lice can live up to 30 days on a person's head. To live, adult lice need to feed on blood. If the louse falls off a person, it dies within two days.

How it is Caused

Lice crawl, they don’t jump. You get them by:

Close contact with someone who already has head lice
Sharing infested clothing, such as hats, scarves, coats, sports uniforms, or hair ribbons
By using infested combs, brushes, or towels
By lying on a bed, couch, pillow, carpet, or stuffed animal that has recently been in contact with an infested person

How it is Diagnosed

If people have any symptoms, they may be one of the following:

Tickling feeling of something moving in the hair.
Itching, caused by an allergic reaction to the bites. Irritability.
Sores on the head caused by scratching. These sores can sometimes become infected.

Lice are diagnosed by looking closely through the hair and scalp for nits, nymphs, or adults. Finding a nymph or adult may be difficult; there are usually few of them and they can move quickly. If crawling lice are not seen, finding nits within a 1/4 inch of the scalp confirms that a person is infested and should be treated. If you only find nits more than 1/4 inch from the scalp, the infestation is probably an old one and does not need to be treated. If you are not sure if a person has head lice, a health care provider, school nurse, or a professional from the local health department should make the diagnosis.

Prevention

Lice are most commonly spread directly by head-to-head contact and indirectly though sharing contaminated clothing or belongings. Teach your child to avoid playtime and other activities that are likely to spread lice.

Avoid head-to-head contact common during play at school and at home (slumber parties, sports activities, at camp, on a playground).
Do not share clothing, such as hats, scarves, coats, sports uniforms, hair ribbons, or barrettes.
Do not share infested combs, brushes, or towels.
Do not lie on beds, couches, pillows, carpets, or stuffed animals that have recently been in contact with an infested person.