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Indiana State Department of Health

ISDH Home > About the Agency > Schools Communicable Disease Guide > Pediculosis (Lice) Pediculosis (Lice)

Clinical Description
Pediculosis capitis is an infestation of adult lice or nits (eggs) in the hair on the head.  The head louse lives close to the scalp and are most visible behind the ears or at the base of the neckline.  Lice depend upon human blood to exist and can only survive up to two days away from the scalp. The main symptom of a head lice infestation is itching.

Incubation Period
Optimally, eggs hatch in a week, and the resultant lice are capable of multiplying in 8-10 days. The typical adult louse lives 20-30 days and lays 4-5 eggs a day; however, the eggs will only hatch if they are less than 1 week old and are near the scalp. 

Mode of Transmission
Transmission occurs by direct head to head contact with a person with a live infestation, or less frequently, direct contact with their personal belongings that are harboring lice, such as combs, hairbrushes or hats. 

Period of Communicability
A person can spread lice as long as live lice remain on an infested person and/or eggs (nits) in hair are within a ¼" from the scalp. Head lice are most common among children attending child care or elementary school.

Exclusion/Attendance
School nurses should work with their administration and LHDs to implement a policy regarding head lice and attendance. A lack of scientific evidence hinders the ISDH from endorsing any policy; however, it should be noted that most school systems no longer support a “no-nit” policy.

Prevention/Care

  • Instruct parents/guardians to use the pediculicides as directed in the package insert, detection of living lice more than 24 hours after treatment suggests treatment failure, a repeated treatment with the same pediculicide 9-10 days after the first treatment may be necessary to rid the child of infestation.
  • Household contacts should be evaluated for lice or nits, and if infested, should be treated at the same time as the child. Parents are encouraged to comb out and completely remove all nits.   
  • Parents should be instructed in home control measures, including laundering items used the 2 days prior to treatment in hot soapy water. Brushes and combs should be thoroughly cleaned or boiled.
  • Insecticide treatment of the home is not indicated.
  • Presence of lice is not indicative of poor hygiene or unhygienic environment.
  • Head lice rarely cause direct harm; they are not known to transmit infectious agents from person-to-person.
  • There is a lack of scientific evidence as to whether suffocation of lice with occlusive agents is effective in treatment.

Other Resources
Indiana State Department of Health Quick Fact Link:
http://www.in.gov/isdh/21929.htm

Centers for Disease Control and Prevention (CDC) Link:
http://www.cdc.gov/lice/

Harvard School of Public Health Link:
http://www.hsph.harvard.edu/headlice/lice.pdf