Advice From Our Doctors

Head Lice: Fact vs. Fiction

Suzanne Christie, M.D.


Lice. One word so terrifying it makes any parent’s skin crawl. But how much do you really know about lice? Get the facts here.

Fiction: Head lice are caused by poor hygiene.
Fact: Head lice are NOT causes by poor hygiene. Head lice have no preference between clean and dirty heads and they infest all races and all socioeconomic classes. In fact, lice have co-existed with humans since ancient times.

Fiction: Head lice carry diseases.
Fact: Head lice do not carry any diseases.

Fiction: Lice can jump from one person to another.
Fact: Lice cannot fly or jump. They are transmitted by close contact with an infested host.

Fiction: Lice may be acquired from a pet.
Fact: Pets do not carry lice.

Fiction: A louse can survive up to a week away from its human host.
Fact: A louse can only survive a day or so away from a human host.

Fiction: “No nit” policies help control the spread of head lice in school communities.
Fact: “No nit” policies are outdated. They are based on hysteria and misinformation rather than on objective science. Find out what really works below.

The Facts

There are an estimated 6 to 12 million infestations of lice annually. Children between ages of 3-11 are at highest risk for infestation. About 1 in 10 children will have had head lice by 6th grade.

Adult head lice are grey or brown wingless insects about 1/8 inch long (about the size of a sesame seed). Lice can be found on the scalp most commonly behind the ears and the neck. The female louse lives up to 3-4 weeks and can lay approx 10 nits (eggs) per day. The eggs are deposited at the base of the hair shaft and a nymphal (baby) louse hatches from its egg after about 8 days of development. The nymphal louse attains the adult stage (capable of laying eggs) about 9-12 days after hatching. Eggs can not hatch at temperatures lower than the scalp. The nymphal louse must start feeding on a human host within a few hours after hatching.

What are the symptoms?

The most common symptom of lice is an itchy scalp. The scalp itches because the small amount of saliva the louse injects into the scalp while taking blood every few hours can cause irritation. But, for some people itching may not develop for 4-6 week so during school or group outbreaks, parents should check their child’s head regularly (and not wait for symptoms to appear).

How do I know if my child is infested?

The gold standard for diagnosis is finding a LIVE LOUSE on the head. An infested person usually has fewer than a dozen active lice on the scalp but may have hundreds of nits (viable, dead or hatched eggs). Nits may be easier to spot (because they are white) but they must be distinguished between other debris- dandruff, dirt, etc. The way to distinguish between the two is that other debris comes off the hair shaft easily, but Nits are “glued” on the hair shaft.

My child has lice now what do I do?

Treatment

Permethrin 1% (Nix) is recommended as first line treatment. You shampoo the hair with a non conditioning shampoo, towel dry, and then apply Nix which comes as a crème rinse. You leave the Nix on for 10 minutes and then rinse it off. You shouldn’t wash hair for 2 days after treatment because the Nix leaves a residue on the hair and scalp that is designed to kill the nymphs emerging from the 20-30% of eggs not killed by the first treatment. You should repeat the same steps 7 days later.

Combing

Treatment with Nix should be combined with daily manual removal of lice and nits (especially those close to the scalp) with a nit comb. Comb your child in a well lite place and divide the hair in at least 4 sections to comb through separately. Combing can take several hours depending on the volume of hair and degree of infestation, but DAILY COMBING FOR LICE AND NITS IS ESSENTIAL FOR SUCCESSFUL TREATMENT

You should also check all household members and those who have live lice or nits less than 1/2 inch from scalp should be treated (if they are farther than ½ inch from the scalp they are usually non-viable and should not be worried about). You should treat family members that share a bed with an infested person even if no live lice are found.

If your child does have lice you should report it to your child’s school and all close contacts because early infestations are easier to treat and eradicate and doing so can also help reduce the risk of your child being re-infested later. Open communication will reduce the social stigma associated with head lice.

What about Resistance?

Resistance to the common treatment is reported but it is not known how common it is. If live lice persist after 2 treatments you should talk to your doctor about a prescription medication

What things do I need to clean?

You should only consider cleaning items that have been in contact with the head of the infested person in the last 24-48 hours (the lice will be dead if they have not been in contact with a human host longer than that). You should clean the hair care items and bedding (e.g. pajamas, towels, stuffed animals) of the infested person. Washing, soaking, or drying items at a temperature greater than 130° will likely kill stray lice/nits. Items that can’t be washed can instead be bagged in plastic for 2 weeks. You may also want to consider vacuuming your car seat cover and any upholstered furniture, but you should not use Pediculicide sprays or treat your pets.

The bottom line

Having lice isn’t a sign of poor hygiene. If we all have cccurate information we can reduce the “lice hysteria.” If your child has lice than you should treat them with permethrin and diligent daily combing for lice and nits for 2 weeks. Even if your child does not have lice you should routinely check them during outbreaks.

 

References
Mill Valley Pediatrics   Phone: (415) 383-3500   Fax: (415) 383-3554