San Diego Schools Head Lice Fact Sheet


A positive diagnosis of head lice is made only when live lice are found. Lice, although a nuisance, have not been associated with any disease process. Head lice can affect anyone in all the socioeconomic groups and do not represent poor hygiene.

Definition and Cause:

Head lice are small, tan-colored insects (less than 1/8"long) that live on blood they draw from the scalp. The eggs (nits) are gray/white and about the size of the head of a pin. The lice and eggs are found on the hair. Lice can live only 1-2 days away from the scalp. Head lice crawl; they do not jump or fly. One sign of lice is an itching head.

How Head Lice are spread:

They are spread from one person to another by direct contact with hair or head gear of infected people; or by the sharing of items such as combs, hats, and other clothing.
They are spread only by crawling lice (not nits).

Incubation and Contagious Periods:

Incubation: 6-10 days from laying to hatching of eggs. Lice can reproduce 2-3 weeks after hatching.

Contagious period: until treated with a chemical that kills lice and viable eggs have been killed or removed.


• Apply head lice treatment (over the counter or prescription) specifically made for killing head lice. Parents should be encouraged to call their child's doctor for a treatment recommendation. Treatments come in a variety of forms such as shampoo, cream rinse, and gel. Follow the directions on the label as recommended by the manufacturer.

• After the hair has been treated, all eggs should be combed or hand picked from the hair.

• While hair is still damp, comb hair through to remove tangles. Then remove nits from the hair shaft. You will need a bright light (and magnification, if available) to see the nits; a fine-toothed comb, preferably made of metal, to strip the nits; a good book or video may assist in keeping the child occupied. Comb the hair from underneath, small sections at one time. To prevent re-infestation, it is essential to inspect the hair daily for one week. Continually strip any nits you may have missed by running your fingernails down the hair shaft. Although complete removal of nits is time consuming, it is necessary.

• Inspect all family members and treat if live lice are found. Children under 2 years of age and pregnant mothers should not be treated without consulting with a doctor.

• Lice infestations on people can be quickly and easily treated. However, unless the sources of re-infestation are also eliminated, you can become re-infested.

Lice can survive in the environment for 24 - 48 hours.

The following environmental treatments are recommended:
a. Excessive housecleaning is not necessary; however, you should vacuum furniture, rugs, and floors.

b. Wash all recently used bedding & washable clothing in hottest cycle for 20 minutes.

c. Heat pillows, blankets, or other fabric items in clothes dryer at hottest cycle for 20 minutes. If dryer is not available, or for items that cannot be laundered with hot water, these items can be kept in a plastic bag for 10 days, if there is a concern about lice having crawled from an infested child onto these items.

d. Clean child's combs, brushes, and other hair accessories such as clips and barrettes in hot water for 5 minutes; or solution of 1/4 cup bleach in 1 gallon of water for at least 10 minutes.

e. Spraying an insecticide on furniture, rugs, or pets is not recommended.


• Encourage children not to share headgear, towels and bedding.

• Provide storage so that clothing or personal items of one child do not touch the other (eg. Hooks placed wide apart, plastic bags for personal items).

• Encourage parents to incorporate inspecting child's hair as part of their regular hygiene routine.

• Parents to notify the school whenever their child has head lice.

School Management:

• Educate caregivers, families and designated school staff how to recognize lice and nits.

• Check children observed scratching their heads for lice; check all close contacts (e.g. siblings if at same school). Mass screenings (school-wide or whole classrooms) is not evidence based practice and not recommended by national pediatrician and school health professional organizations

• Have parent/guardian consult their healthcare professional for a treatment plan.

• Follow environmental treatments listed above, as applicable.

• School Nurse to provide education to families and school staff to dispel myths and stigmas on the relatively benign consequences of head lice infestation.

• Parents or groups of parents may not be used to inspect students for head lice. This is a violation of student confidentiality.

School Exclusion and Readmission:
• Children with identified live head lice are referred for treatment at the end of the school day. Until the end of the school day, avoid activity that includes head-to-head contact with other children or sharing of any headgear.

• Return to school after the child has received the treatment recommended by the child's health professional. A trained staff member rechecks the student before returning to class.

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