Scratching your head over lice? You’re not alone, but experts say don’t panic


Head lice have long been a source of distress for parents. And with recent news of burgeoning resistance to over-the-counter treatments, those worries are escalating. “Please help!!!” read one recent post on from a mother concerned about an infestation in the waist-length hair of her 13-year-old daughter. Another mom responded that if her boys got lice, she would shave their heads.

But as another school year ramps up, researchers and nurses are working hard to get out an important message: Do not panic. Lice don’t carry diseases. They don’t jump, fly or crawl around on furniture, which means they don’t spread as easily as most people think. And even though popular lotions and shampoos are less effective than they used to be, they still work sometimes. When they don’t, new options are available.

Most important, lice are no reason to miss school, says Beth Mattey, president of the National Assn. of School Nurses in Wilmington, Del. Two decades ago, periodic screening blitzes sent students home if they had any sign of lice or eggs, called nits, in their hair. But that led to embarrassment for kids, missed work for parents, lost learning time and even bullying, while follow-up data showed no sign that the practice made any dent in lice populations. Today, the American Academy of Pediatrics and other groups recommend that children with lice be allowed to stay in class. After all, by the time the insects get discovered on someone’s head, they’ve likely been there for a month or more.


Busting myths

Head lice have been with us since antiquity, and false beliefs about them are just as persistent. According to an often-quoted statistic, 6 million to 12 million kids ages 3 to 11 get lice each year in the U.S. But that estimate is based on extrapolations of product sales, and actual numbers are likely far smaller, says Richard Pollack, a public health entomologist at Harvard University. For one study, he examined more than 10,000 kids in schools around the country and found active infestations in an average of just 1% of kindergartners through fourth-graders. Based on current census data, that would add up to about 250,000 kids in that age group with lice at any given time. Around fifth grade, for reasons that still aren’t clear, cases drop precipitously.

Despite ongoing concerns about lice lurking on sofas and under sheets like bed bugs do, researchers have also dispelled the enduring notion that lice spread readily via combs, barrettes, hats and pillowcases. One study found lice on the pillows of just 4% of infested people. And because head lice can’t live for very long off of a human host, direct head-to-head contact generally is required for a louse to move from one person to another. It doesn’t matter how often kids bathe; their risks are the same.

And even though back-to-school time is a popular season for worrying about, checking for and diagnosing the bloodsucking parasites, infestations don’t seem to occur more often at any particular time of year. “They only survive in one place, and that’s on the scalp of a person, usually a child,” Pollack says. And on a kid’s head, temperature and humidity generally remain constant, “regardless of whether it’s January or August.”

New concerns

Lice are changing in worrisome ways, with recent news that many are becoming resistant to pyrethroids, the family of chemicals in the most popular over-the-counter treatments, including Nix and Rid. In 2000, permethrin (a type of pyrethroid and the active ingredient in Nix) worked against lice 100% of the time, says John Clark, a pesticide toxicologist at the University of Massachusetts, Amherst. But by 2013, clinical studies showed, it eliminated lice in just 25% of cases.


A rapidly spreading genetic mutation is the culprit, according to growing evidence. In 2012, some 88% of lice had the mutation, Clark’s team announced recently at a meeting of the American Chemical Society. In a newer, still preliminary analysis, a mutation rate of 99% was found.

Pollack still recommends trying Nix or a related product after a new diagnosis, because mutations don’t necessarily confer immunity. After all, a kit can cost less than $10, and you might get lucky — as long as you’re dealing with lice and not something else.

What is it, really?

Even for people on the front lines of lice diagnoses — mainly school nurses — false positives are rampant. Nits are particularly challenging to identify correctly, as all sorts of other things look like them, including dandruff, crumbs, sand and droplets of hair products. Before you scrub insecticides into your kids’ hair, Pollack suggests cross-checking what you see with images available online.


How to deal with resistant lice, and why they may not be so bad

If you’re sure you’ve got lice, and they withstand a round or two of drugstore products, there are other approaches available. In one recent analysis, Consumer Reports suggests physically and repeatedly removing lice with a fine-toothed comb over the course of days and weeks until they are all gone. That can be tedious and nearly impossible for some caretakers, who might opt instead for a doctor’s visit.

For the lice-weary, prescription medicines approved by the Food and Drug Administration now include a lotion called Sklice, which was introduced in 2012 and interferes with a different part of the insect’s nervous system through an active ingredient called ivermectin that is produced by fermenting bacteria. Two days after treatment with Sklice, according to a 2012 study, 95% of people were louse-free. That number dropped to 74% two weeks later. Natroba, which came out in 2011, is another new product that attacks yet another area of the nervous system. No combing is necessary, and it claims to be 85% effective after two weeks.

A third prescription option is Ulfesia, which has been available since 2009 and is made with benzyl alcohol that suffocates the lice but doesn’t harm the eggs. There’s also an older drug called Ovide, made with malathion, which has long been used as a pesticide against all kinds of insects. But many lice are resistant to that one now too. Some of these products require two applications. And some are only safe for kids over a certain age or size, making it worth talking to a doctor about the pros and cons, including the hefty price that many of the new products command. By keeping newer drugs locked behind prescription barriers, one hope is to avoid the kind of overuse that may have contributed to resistance against older treatments.

And if you are squeamish about the little critters, or you want to avoid drugs, there are any number of commercial agencies that will comb and check heads. Some even make house calls.

It turns out that doing nothing often gets rid of lice too, eventually. One possibility is that a course of antibiotics for an ear infection or some other illness extinguished the lice, which feed off of our blood and are often susceptible to the drugs. Or it might be that, even after years of being colonized, kids sometimes age out of lice, which thrive best on younger heads.

Whatever your approach, resist the urge to respond with horror at the sight of vermin in your children’s hair, experts say. Refusing to hug them for fear of catching an infestation or feeling like a failure for letting it happen won’t do your kids any good. Richard Pollack, a public health entomologist at Harvard University, offers a different kind of reaction, perhaps one that comes naturally only to an entomologist: “I encourage parents to clap their hands together and smile and say, ‘Of all the things my child could bring home from school, it’s only head lice!’” Meningitis, influenza, pinworms and even colds are, he says, far worse. A case of lice may be a nuisance, but it’s a sign that you belong to a community. “A kid is not going to get head lice unless he or she has friends. This is a social disease.”

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