Head Lice: Things that go itch in the night…or anytime, really

Kids are back in school, sharing books, pencils, and jump ropes…and they could also be sharing head lice!

Head lice definitely cause heightened anxiety in parents and schools, but in actuality, they do not spread disease, are not a health hazard and are not a sign of poor hygiene.  Although difficult to accept for those affected, lice infestation is rather benign.  (Of course, the scratching isn’t so easy to deal with!)

Who is affected?

Head lice, or “pediculosis capitis,” are found worldwide, and infestations occur among all socioeconomic backgrounds.  An estimated 6 to 12 million infestations of head lice occur in the U.S. each year.  Infestation is most common among children 3 to 12 years of age.  In fact, excluding the common cold, head lice affects more elementary school students in North America than all other communicable diseases combined.

What is a head louse? 

The head louse is a grayish-white insect 2 to 4 mm in length. It is about the size of a sesame seed. The life span of the female is about one month. Once mature, she lays 7 to 10 eggs each day.

The eggs, commonly called “nits,” are oval capsules that hatch in eight days, releasing nymphs that require another eight days to mature. After hatching, egg cases (also called “nits”) become white and more visible. The nymphs mature over the next 8-12 days. Once adults, they can mate and the cycle starts over again.

How are lice transmitted?

The most likely form of transmission is direct contact with the scalp. Lice cannot fly, hop or jump. They can only crawl.  

Other theories on how they spread include cross-transfer from articles of clothing on adjacent hooks and shared combs, hats, headphones, or towels. However, this type of transfer is rare.  Also know that pets are not sources of transfer.

How do I know if my child has lice?

It can be hard to know, as most lice infestations are asymptomatic. Some children affected may even house a large number with no apparent symptoms. Itching results from sensitization to the louse’s saliva. However, this sensitization may take up to 4 to 6 weeks to materialize. Scratching can lead to secondary bacterial infection like impetigo. Pediatricians and parents should be suspicious that lice are present when children suffer from skin infections near the neck and ears.

What is the best way to diagnose lice? 

The diagnosis is made by seeing live lice. However, this can be an arduous task given that they avoid light and crawl quickly. Studies have revealed that using a louse comb is more efficient for diagnosis than visual inspection. Some experts suggest that wet combing (with water, oil or conditioner as a lubricant) may be better than the dry technique, but this has not been compared in clinical studies.

Nits may be more easily noticed than live lice. However, examiners tend to mistake hair casts, dandruff, and debris for nits. Nits are firmly attached to the hair shaft and are much harder to remove than these other entities. Yet, nits without lice do not automatically indicate an active infestation. Nits may last for months despite successful treatment.

How do I prevent lice?

• Remind children not to share combs, brushes and hats.
• Identify affected children and treat promptly.
• It is not recommended to treat for lice unless the diagnosis is confirmed

How do I treat lice?

Once a visual diagnosis of head lice has been made, treatment with a pediculicide, a topical shampoo-like treatment, should begin.  Since no treatment is 100% effective, manual removal of nits after treatment is recommended, using the following procedure:

• The task is easier with a fine-toothed nit comb
• The hair should be wet, with an added lubricant such as hair conditioner, vinegar, or olive oil
• The hair should first be brushed or combed to remove tangles
• Insert the fine-toothed comb near the crown until it gently touches the scalp, and then draw it firmly down and examine for lice after each stroke

Combing should be continued until no lice are found in each session, with repeat sessions every three to four days for several weeks, continuing for two weeks after any session in which a large, adult louse is found. The procedure may take 15 to 30 minutes.

When can my child return to school?

The AAP states that no child should be restricted from school due to head lice. Most researchers recommend that schools should abandon “no nits” policies. It is felt that children can return to school immediately after completion of the first application of a topical treatment or after the first wet combing session.

About Dr. Brittanny Boulanger

Brittanny Boulanger, MD, practices pediatrics at Harvard Vanguard Medical Associates in Burlington.  A Dartmouth College graduate, she completed her medical degree at the University of Massachusetts Medical School in 2000. She pursued a pediatric residency and chief residency at the University of Rochester in Rochester, NY.  Her interests include pediatric obesity and medical student teaching. She currently holds a monthly shared medical appointment (SMA) called SMArt Kids, which addresses the issue of pediatric obesity.  She is the pediatric coordinator for the Harvard Medical School Patient Doctor II course. She also serves on the Executive Board of the Massachusetts Chapter of the American Academy of Pediatrics and the Massachusetts Medical Society Committee on Medical Education.