Amy Movius MD
Head lice are a “back to school” consideration most would rather not think about. Infestations with lice are common, as are the myths surrounding them.
Head lice are largely an annoyance. Head lice are NOT a health hazard, NOT a sign of poor hygiene, and do NOT spread disease. Head lice affects between 6-12 million children between 3 and 12 years of age yearly. Frequency of shampooing/bathing and length of hair do not matter. All socioeconomic groups are involved. African Americans are less often infested because of a unique hair follicle shape. Otherwise, lice are an equal opportunity pest.
Head lice DO itch and scratching can rarely lead to a bacterial skin infection. More pertinent, is that head lice infestations are an inappropriate source of embarrassment, stigma, and missed school and work.
Head lice do NOT hop or fly. Adult lice do crawl, and they can be pretty quick and thus hard to see. They are transferred by “head to head” contact, such as sharing a bed, but are not casually picked up. Screening of classmates is done because of possible inadvertent “head to head” contact. Likewise, sharing of brushes and grooming supplies is discouraged because of a theoretical risk of transmitting lice on the bristles. This risk is considered quite small, as any louse found on a brush is probably dead. As one source put it, “a healthy louse is not likely to leave a healthy head”.
The only way to definitely diagnose a head lice infestation is to see an adult louse crawling on a scalp. More commonly, the nits or eggs are inspected for. Identifying active head lice infection is difficult and imperfect, both in missed infestations as well as mis-identified infestations. Specimens submitted as nits by doctors, nurses, teachers and parents have turned up everything from dandruff, to hairspray droplets, to dirt and other debris. Of those children correctly identified as having nits, less than 1 in 5 develops an active lice infestation.
Diagnosing the presence of nits should ideally be done by someone with experience doing it. Nits are often best seen around the nape of the neck and behind the ears. They can only survive within 1 cm of the scalp and they stick to the hair when you try to remove them. If they are found farther away they are either not nits, or dead nits. Nits are NOT infectious (remember they are eggs, and eggs don’t crawl) and are NOT an indication to miss school. In the past there have been “no nits” policies at school. This is unnecessary and ill-informed. In fact, if a child has active (mature and crawling) head lice, their parents should be told and they should be treated that night. They do not need to be sent home from school or stay home from school the following day.
So, what about treatment? The challenge in treating head lice is that the available therapies do not kill eggs, thus multiple treatments are needed. The first treatment kills the entire population of potentially contagious lice but leaves the nits. Given time these nits will hatch, mature and lay more nits. Permethrin (Nix) is the over-the-counter treatment of choice for head lice and a recent publication recommends the timing of a second treatment 9 days after the first as likely effective for eradicating all lice. It is not unduly expensive and is very safe. Unfortunately, lice can be resistant to permethrin in which case your medical provider can prescribe other medications.
Non-pharmacologic products and home remedies for head lice are prevalent and thus worth reviewing. Occlusion therapy refers to smearing a substance on the scalp to essentially suffocate the lice. Mayonnaise, petroleum jelly, olive oil, vinegar, butter and isopropyl alcohol have all been used. The bottom line is that occlusion therapy is NOT effective. Likewise hair removal has been proposed. The head has to be shaved to remove the eggs, which are located very close to the scalp. While effective, this is NOT necessary. Lastly, nit combs help remove the sticky eggs close the scalp and may be a useful addition to pharmacotherapy, but are NOT enough by themselves.
Drastic cleaning measures are unnecessary. Vacuuming floors and furniture is adequate for these surfaces. It is not necessary or advisable to spray furniture, floors or other surfaces with permethrin. This can actually be dangerous and these substances can be absorbed through the skin. Clothes, bed linens, and items that have been in “head contact” should be washed in hot water and dried in hot clothes dryer. Items that can’t be washed can be dried for 15 minutes on high heat, or in lieu of washing or drying, placed in a plastic bag for 2 weeks.
In summary, head lice is an unpleasant but minor annoyance we all have to worry about. Head lice is not dangerous and should be manageable without disruption of school and work routines.
Frankowski et al. American Academy of Pediatrics, Committee on School Health the Committee on Infectious Diseases. Head Lice. Pediatrics 2002;110:638-643
Lebwohl et al. Therapy for Head Lice Based on Life Cycle, Resistance, and Safety Considerations. Pediatrics 2007;119:965-974