Head Lice

In the United States it is estimated there are 6 to 12 million infestations of head lice (Pediculus humanus capitis) each year among children 3 to 11 years of age. Head lice are not known to transmit disease and therefore not considered a health hazard but a nuisance pest. Head lice are ectoparasites whose only hosts are human. The louse must feed on human blood several times daily and reside close to the scalp to maintain its body temperature.  
Head lice are usually spread by: 
  • Coming in direct contact with the hair of a person who is infested with lice. Such contact is common among children during play at school, home, or elsewhere (camp, slumber parties, sports, etc.).  
  • Wearing clothing, such as hats, scarves, coats, or hair ribbons worn by an infested person.
  • Using infested combs, brushes, or towels, or
  • Lying on a bed, couch, pillow, carpet or stuffed animal that has recently been in contact with and infested person.

Getting head lice is not necessarily related to the cleanliness of a person or their environment.

Symptoms and Diagnosis:
Head lice infestations may not have symptoms, especially at first when an infestation is light. Usually the first and most common symptom of head lice is itching which is caused by an allergic reaction to louse bites. However, it may take 4 to 6 weeks for itching to appear. 

Other symptoms include:
  • A tickling feeling or a sensation of something moving in the hair; 
  • Irritability and sleeplessness; and
  • Sores on the head caused by scratching.
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Diagnosis of head lice

 infestation is best made by finding a live juvenile or adult louse on the scalp or hair of a person. However, lice move quickly and avoid light, finding them may be difficult. 

If crawling lice are not seen, the presence of nits (eggs) strongly suggests a person is infested. Live viable nits are usually firmly attached to the base of hair shafts within 1/4 inch off the scalp. Nits are frequently located on hair behind the ears and back of the neck. Nits can be confused with other particles found in hair such as dandruff, hair spray droplets, and dirt. Nits that are found more than 1/4 from the scalp are almost always hatched or dead

The presence of live lice and/or viable nits indicate a person has an infestation and needs to be treated.
Prevention and Control of Head Lice
Head lice are spread most often by direct head-to-head contact (hair-to-hair) contact. Also, they can be spread by sharing clothing, bedding, or articles onto which lice have crawled. In addition, an infestation can be acquired by sitting on a couch, chair, or on upholstery in an infested environment. 

The following steps can be taken to help prevent and control the spread of head lice.
  • Avoid head-to-head contact during play and other activities while at home, school, playground and elsewhere.
  • Do not share clothing or articles such as hats, scarves, coats, hair ribbons, ear phones, barrettes, combs, brushes, towels, etc.
  •  Disinfest combs and brushes used by an infested person by soaking them in hot water (at least 130 degrees F) for 10 minutes.
  • Do not lie or sit on beds, couches, chairs, pillows or carpets that have recently been in contact with an infested person.
  • Machine wash and dry clothing and bedding used by an infested person using a hot water laundry cycle and high heat drying cycle.
  • Articles that are not washable can be sealed in a plastic bag and stored for 2 weeks.
  • Vacuum the carpet, floor, furniture and bed in an infested environment.

For more information visit the Centers for Disease Control (CDC) website.

Last Update: 4/12/2011

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