Lice (pediculosis capitis)


Lice (pediculosis capitis)

Lice (pediculosis capitis) can cause intense itching, which can result in scratching and areas of bloody skin crusts.

Head lice (pediculosis capitis) are a common, highly contagious infection that often occurs in nurseries, day care centers, and schools. It is caused by infestation with the human head louse, Pediculus human’s capitis, and it is usually very itchy.

Lice are very small insects that feed on human blood. The female louse attaches her eggs (nits) to the base of the hair near the scalp, and the nits hatch 7–10 days later.

Who's at risk?

Head lice can occur in anyone, but children aged 3–11 are most likely to become infested. All socioeconomic groups can be affected, and infestation is not related to the cleanliness of the person or their environment. Because the louse’s claws are better able to grasp certain hair types more than others, those with course, curly hair are affected less often than those with smoother hair types. In addition, girls are more likely to have head lice than boys, possibly because they tend to have longer hair. Head lice infestations are most often seen in situations in which there is close personal contact, such as schools, home, playgrounds, sports, and camp. Lice eat only human blood. Therefore, pets and other animals do not spread the infection.

Signs and Symptoms

Moving lice or nonmoving nits may be seen on the scalp and hair. Each louse is approximately 1–3 mm long and is whitish-gray in color. Lice crawl; they do not jump or fly. Nits are lesser, about 0.5–1 mm, white, and are firmly attached to the hair very close to the scalp.

Little red bumps or sores may be seen on the scalp, neck, and shoulders. Occasionally, the lymph nodes behind the ears or in the neck may be swollen and tender. Lice may sometimes be seen on the eyelashes, causing the eyes to become red and irritated.

Because head lice infestations are quite itchy, scratching is common and may lead to resultant infection or scabbing. In addition to an itching or tickling sensation, children may also be irritable or have difficulty sleeping.