Heads up: Don’t panic
Head lice have long been a source of distress for parents. And with recent news of burgeoning resistance to overthe-counter treatments, those worries are escalating. “Please help!!!” read one recent post on Babycenter.com from a mother concerned about an
But as another school year ramps up, researchers and nurses say: 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, a bunch of new options are available.
Most important, lice are no reason to miss school, says Beth Mattey, president of the National Assn. of School Nurses. 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.
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 fourthgraders. 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 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.
Pollack still recommends trying Nix or a related product after a new diagnosis, because mutations don’t necessarily confer immunity. 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 and sand.