West Irondequoit Central School District

Head Lice Information

Background

Definition:  Head lice is an infestation of a wingless insect that survives by taking nourishment from a human scalp.  The adult louse is 2 to 3 mm long (the size of a sesame seed).  The female lives up to 3 to 4 weeks and lays about 10 eggs, or nits, a day.  These tiny eggs are firmly attached to the hair shaft close to the scalp by a strong adhesive that is produced by the insect.  Once the eggs hatch, nymphs leave the protection of the shell, grow for 9 to 12 days, reproduce, and the females lay more eggs. To escape detection, the color of the live nit adapts to the color of the hair of the infected person. The empty nit casings however, tend to appear white and are seen more readily by the naked eye.  When provided with the warmth of a human host, each egg is hatched in 10 to 14 days.  This cycle can repeat itself every 3 to 4 weeks if left untreated.  To survive, the louse injects tiny amounts of saliva into the scalp and removes small amounts of blood from the scalp every few hours.  The injected saliva is what causes the itchy irritation for the human host.  Itching may be delayed for 4 to six weeks if the host is infested for the first time.  Head lice can NOT survive off the human host for more than 1 day because it needs the temperature of the scalp for warmth and for food.

How frequently does head lice infestation occur?

This infestation is most common in children 3 - 12 years of age in the United States and  accounts for about 6 to 12 million cases each year.  ANY child can be affected but it is less common in black children because of their oval hair shaft. Head lice are not a health hazard or a sign of uncleanness.  They are NOT responsible for the spread of any disease.  The most common symptom is scalp itching. 

How do head lice spread?

Head lice spread by crawling.  They do not fly or jump. However, they can crawl very quickly, as fast as 3 to 15 inches per minute.  When children who are infested have close head contact with another child, the louse can crawl to another scalp.  Indirect spread through contact with personal belongings of an infested individual (combs, brushes, hats) is much less likely.  However, it is wise to avoid sharing personal belongings.  Lice found on combs are likely to be injured or dead, and a healthy louse is not likely to leave a healthy head.  Pets do not have head lice and cannot spread them.

How does someone know if a child has head lice?

If a live louse is found on the head, this confirms the diagnosis of head lice.  However, this is not as easy as it sounds, since the louse is such a fast mover.  Sometimes, the tiny eggs, or nits can be seen at the nape of the neck or behind the ears, within ½ inch from the scalp.  Remember, they are firmly glued onto the hair shaft and are difficult to remove.  In general, nits found more than ½ inch from the scalp are unlikely to be alive.

Management of head lice requires proper treatment under the advisement of a primary care physician. The school nurse is very knowledgeable about current FDA approved head lice treatments and can also answer your questions.  The school nurse is available to check a student’s head and review the treatment method used in the home.   Nit removal by the parent or guardian at the time of treatment is strongly recommended. Removal of all nits within ½ inch of the scalp will decrease the small risk of self-reinfestation.

The school nurse practitioner and physician are also available for consultation.

Respectfully submitted,

Larry Denk, M.D.                                                                   Mary Lou Pulcino, M.S., P.N.P

WISD Pediatrician                                                                  WISD Pediatric Nurse Practitioner