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Posted by Daniel Engber

https://www.theatlantic.com/science/2026/03/lice-wars/686611/?utm_source=feed

The human-head louse has a ghostly quality. It tends to glimmer in and out of view, leaving only subtle signs and omens of its presence. Is that oblong speck an egg sac or a flake of dandruff? Was that a prickle on your scalp? Is it normal that your son is scratching just behind his ear? Maybe you have lice and he has lice, and you’ve all had lice for weeks. The possibility is frightening. The uncertainty leads to madness.

The louse evolved to be intrepid and sneaky. Its behavioral imperative is simple and relentless: “They are naturally negatively geotropic,” Ian Burgess, a medical entomologist who runs a company that tests insect-control products, told me. “They will always climb upwards towards the head.” He recalled a day when one must have fallen on his shoe during a comb-out in his lab. He was driving home that afternoon and noticed that the bug was sitting on his knee, apparently confused. “It had climbed to the highest point it could get, and it didn’t know where to go from there.”

Once the bugs ascend, they suck your blood and attach their eggs to the roots of your hair. Within a month or two, your skin might start reacting to the parasites’ saliva, and some degree of itching will ensue. But otherwise, a case of head lice has no ill effects. “To say the truth, head lice are not a real medical problem,” Kosta Mumcuoglu, a lice entomologist at the Hebrew University of Jerusalem, told me. Still, their presence is unwelcome, to say the very least. Emergency scalp checks, precautionary treatments, instant-onset symptoms of delusional parasitosis: “It is definitely a psychological, emotional problem,” Mumcuoglu said.

Mumcuoglu is an expert, but this was not a useful insight. I have two kids in elementary school. I am quite familiar with the psychological, emotional problem that is lice.

For decades now, experts have been trying to convince Americans that the plague of Pediculus humanus capitis is very mild, and that it doesn’t really merit drastic measures; for decades, too, parents have heard the opposite from schools, in the form of urgent letters saying lice have been detected and countermeasures are essential. Along the way, we’ve heard claims and rumors that the head-lice situation is deteriorating—that outbreaks are increasing, that drug-resistant superbugs are taking over. Yet the basic facts of lice remain the same. The parasites are programmed to get up to our heads. We are programmed to let them get inside our minds.

The modern lice wars got their start in Newton, Massachusetts. Deborah Altschuler’s son had lice, and his school implied that this was her fault—that a family like hers would not be welcome anymore. It seemed to her just then, in the early 1980s, that the school itself should have taken more responsibility, that its policies on lice should have been clearer. For that matter, shouldn’t everyone, from parents up to politicians, have been more informed about the problem?

The group she formed out of her home, first called Parents Against Lice and later the National Pediculosis Association, would advocate for aggressive lice-check protocols and more systematic rules for expelling kids from class. If this was not a movement to abolish lice, then it was at least an all-out bid for taking head lice seriously as a public-health concern. With the help of several entomologists at Harvard and the University of Massachusetts, Altschuler pressed the case. At one point, she proposed that head lice were a vector for the virus causing AIDS, spreading it from scalp to scalp. “I felt that AIDS was a wake-up call,” she told me. “We got lucky that it wasn’t insect borne, but it could’ve been.”

[From the September 1987 issue: AIDS and insects ]

Altschuler also worried that the common treatments of the time—various insecticide shampoos either used alone or, more distressingly, in combination—were causing harm to kids. In this and other ways, she was an early incarnation of the MAHA mom: incensed about the failings of the public-health establishment, inclined to do her own research, worried about toxic products and the companies that manufacture them. And in the ’90s, her approach to lice caught on. A new industry of lice consultants and lice-removal salons began to form. Altschuler herself became a known expert in the field. (Her proudest moment, she said, was speaking to the Armed Forces Epidemiological Board in 1992, not long after Operation Desert Storm.) Eventually she’d have a dozen people working for her association, taking about 100 calls a day and selling T-shirts with messages such as Keep your wits, not your nits and Don’t let your child become an egghead.

But even as this wave was gaining strength, a sort of countercurrent formed beneath it. One of Altschuler’s Harvard contacts, a public-health entomologist named Richard Pollack, had begun to worry that the newly fostered panic was unfounded. He knew that the bugs were harmless in themselves; more than that, he believed that they might be far less prevalent than many people suspected, especially the ones who had been reaching out to him with horror stories: “They were telling me that lice had become so common, so abundant, that I could go into any elementary school and collect thousands of them in a morning.” But when he followed up on this idea, and started doing field research on grade-schoolers’ heads, the results weren’t really that alarming. Misdiagnosis was indeed a rampant problem, and the people who were the most upset—the ones who’d put their families through repeated treatments—were the least likely, as he saw it, to actually have lice. “They were stuck in this vicious cycle,” he told me.

A folk entomology of head lice had taken hold, and it entailed a range of false beliefs. Pollack sometimes heard it said that lice could jump from one child’s head to another, and that they were infesting kids from classroom desks and rugs. None of this was true, he said; in general, contagion happens with only direct head-to-head contact—and a louse that falls off a kid at school will soon dry out, infesting no one else. (Mumcuoglu told me that parents needn’t worry about lice-infested furniture or bedding either.)

Even worse, for many schools and lots of parents, the mere presence of a nit, or even a nitlike object in a child’s hair, was prima facie evidence of a dangerous contagion. But a louse’s empty egg sac can remain adhered to growing hair for months, like a shell casing on a dormant battlefield. This is one reason why studies find little benefit from screening kids in class: False positives abound. In 2006, Mumcuoglu estimated that two-thirds of all lice treatments in the U.S. are given to children who don’t have an active infestation. And because many schools send kids home if they’re suspected of having lice, those false positives may add up to as many as 24 million lost days of school. (No one has tallied the time and tears wasted on unnecessary pillow quarantines and the bagging of stuffed animals.)

If Altschuler and her group hoped to raise awareness and concern, then Pollack sought, in part, to tone things down. The two of them had worked together in the ’90s, but inevitably they had a falling out. “Early on, I saw him as a wonderful ally and a helpful person to the cause,” Altschuler told me, “but then he started trying to become us, in his own way, with information that was inconsistent with ours.”

In particular, Pollack and the other head-lice moderates took aim at the unforgiving “no nit” policies in schools, which might exclude a child from the classroom on the basis of a single empty egg sac, and they were winning some important hearts and minds. In 2002, when the American Academy of Pediatrics put out its first clinical report on treating head lice, its authors called no-nit policies “detrimental” and “a response to infestations that is out of proportion to their medical significance.” Two years later, the nation’s school nurses—who have been focused on the scourge of head lice since their profession’s founding in 1902—followed suit. Eventually, some school systems would ease up too. In New York City, where I live, the public schools that service a million students had done away with no-nit policies by 2008.

These were salutary changes, to be sure. Fewer kids would be ejected from the classroom, and presumably some degree of lice-related learning loss was curbed. But the new guidelines did not eliminate the broader set of problems that the parasites create for children and their families. Even though some schools now tolerate nits on children’s heads during the school day, they still communicate aggressively with parents on lice-related matters, encouraging frequent checks at home and better-safe-than-sorry interventions.

No one ever articulates the rationale for treating the mere possibility of lice with more concern than a cold or even COVID. (No one ever gets a letter home from school saying A case of rhinovirus has been detected in your classroom.) But the thinking surely boils down to this: It’s icky to imagine that your child’s hair—and yours!—might at this very moment be aswarm with bloodsucking bugs. Once the lice have gotten to your head, and in your head, no amount of “Just calm down” can make them go away.

If the fear of lice can be recalcitrant, the lice themselves are even more defiant. “It’s an insect that is abnormally subjected to stresses on its survival,” Burgess, the entomologist who tests insect-control products, told me. A louse’s clawlike feet hold fast in both a shower and a swimming pool. Its physiology weathers perfumes and soaps and the bristles on our hairbrushes. And given time enough, its genome may adapt to shrug off almost any poison we apply.

You don’t need to hire experts to dislodge an infestation—humans have managed to delouse themselves since deep antiquity—but the process takes some work, along with proper information. I’m sorry to say that the latter isn’t always near at hand. The New York City schools, for instance, suggest that parents give their kids chemical treatments, naming two kinds in particular—permethrins and pyrethrins—that were obsolesced long ago by insect evolution. America’s head-lice problem will never improve, Mumcuoglu told me with some annoyance in his voice, so long as our institutions insist on making this mistake, particularly about permethrin. (In an emailed statement, the New York City Department of Health said that over-the-counter, permethrin-based products are “an accessible starting point for many families,” but other products may be necessary if “there is treatment failure or suspected resistance.”)

In fact, we do have many other ways of getting rid of lice, even so-called drug-resistant superlice. Ivermectin may not be an anti-cancer, anti-COVID wonder drug, but it’s miraculous at treating parasites: A topical ivermectin cream can likely cure your child of an infestation, and may be purchased over the counter. Ivermectin pills—which could be even more effective—can be prescribed off-label. (Dawn Nolt, the lead author of the American Academy of Pediatrics’ head-lice report, told me that ivermectin may be upgraded to a first-line treatment in the next update to the guidelines.) I happen to be partial to dimethicone, a lubricant that will coat a louse’s body and seal up the holes it uses to get rid of excess water. Since dimethicone’s effect on lice is physical instead of chemical, it may be less likely to provoke resistance over the long term. But Burgess, who first identified dimethicone as a lice-killer, warned me that he’s seeing signs of its waning potency. (Perhaps the louse’s body has been changing shape, he said, and their excretion holes are now harder to plug up.)

[Read: How ivermectin became right-wing aspirin]

And then, of course, there is the fine-toothed comb—a medical device that seems to have been in use by human populations for at least 5,000 years. (Archaeologists have found lice on human mummies, and lice combs in mummies’ tombs.) Combing, when performed with diligence, can sometimes be effective on its own accord, even if it’s also highly, highly inconvenient. Proper combing technique involves sectioning out and clipping up the hair in strips, then combing out each section repeatedly while inspecting for lice and nits that may be the size of sesame seeds. After that, one might need to repeat the entire procedure as soon as two or three days later. Strangely, the AAP guidelines say this process might be beneficial, head lice notwithstanding, in the sense that it allows “a caregiver and child or adolescent to have some close, extended time together.” Extended? Yes. Close? Please be serious. I asked Nolt why the AAP was spreading this absurd misinformation. “We were trying to have a silver lining,” she said.

But there is no silver lining, I’m afraid. In the end, the lice wars have only brought us back to where we started, and also where we’ve always been: worried, inconvenienced, and confused. Pollack says he’s proud of what his 40 years of advocacy accomplished—“an awful lot of kids stayed in school, rather than being sent home,” he said. But he also knows that certain head-lice myths have never gone away, and maybe never will.

When I spoke with Altschuler, she lamented the idea, sometimes floated by today’s head-lice experts, that head lice aren’t so important. “They are important for the people who have them,” she said. This, at least, is a scientific fact.

https://www.theatlantic.com/science/2026/03/lice-wars/686611/?utm_source=feed