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Head Lice Facts and Information

General Information

Head lice are tiny parasitic insects that live on the human scalp and feed on human blood. The adult female louse is about the size of a sesame seed, brown/tan in color, and typically lives for 20 to 30 days. She lays up to 6 pearly-gray oval shaped eggs a night, called nits, that hatch in 7-10 days. Nits are found throughout the hair, usually close to the scalp in temperate climates (egg production occurs at optimum temperature 84 deg.), and are most often located at the back of the scalp, behind the ears, and at the top of the head. They adhere firmly to the hair shaft and cannot be easily moved up or down the hair. The primary mode of transmission is head to head contact. Lice are crawling insects that cannot hop, jump, or fly. They do not generally survive for more than 12-48 hours off the human host. Pets do not get head lice.

Most outbreaks of lice occur at home. Often nurses see an isolated "case" at school indicating that head lice are still prevalent in the community. When multiple children are diagnosed there is often a community activity such as a "sleepover" where the contact occurred.

Most head lice are effectively treated with pediculicides such as over-the-counter pyrethrin -RID, R&C; or permethrin-NIX, which are safe but can sometimes cause scalp irritation.  Lice can also be mechanically removed. Heavy oil based products to suffocate lice are ineffective. The prescription pesticides, lindane-Kwell or malathion -Ovide, can be used for repeated, resistant infestations (contact primary care provider). Nits must be mechanically removed using a lice/nit comb or by hand. There are anecdotal reports that olive oil or vinegar will loosen nits, but there is no data to support this.

Physical Indications of Head Lice

  • Persistent scratching of the head and back of the neck.
  • Red bite marks and scratch marks on scalp and neck.
  • Presence of nits on hair.
  • Presence of lice on scalp and hair.
  • Secondary bacterial infection can occur, causing oozing or crusting. Swollen glands may also develop.


  • Nurses will educate students on an ongoing basis to avoid sharing hats, hair ornaments, hairbrushes, etc.
  • Nurses will check a child for head lice if the nurse or teacher notices the child has increased itching/scratching of the scalp, or at the request of a parent.
  • For suspected cases, nurses will notify parents by sending an informational letter home with the student
  • The nurse will assist parents in a supportive manner to understand lice treatment.
  • The child with head lice may return to school after treatment (continued nit removal will decrease nit hatching and reduce the need for additional treatment).
  • The nurse will screen the student upon return to school. The nurse will check the student on day 7 and day 14.
  • Siblings of diagnosed students will be examined for lice, and nurses of siblings in other schools will be alerted of the situation.
  • When three or more students in a class with no related source (ie. a sleepover) are diagnosed with head lice, the nurse will send a letter to the parents of all students in the class.
  • Classroom practices will be reviewed if there are several cases of head lice in one classroom that do not have a common community source.

Head Lice Prevention Tips

  • Watch for children scratching heads constantly, particularly after holiday or vacation periods
  • Advise children not to share hats, hair ornaments, scarves, barrettes, scrunchies or combs/brushes.
  • As winter approaches keep coats, hats and scarves as separate as possible in school
  • Encourage children to store hats and scarves in coat sleeves
  • Refer unusually itchy children to the school nurse

References and More Information:

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