Head lice. Hard to kill except in Michigan!


Head LiceMillions of children will head back to school this month. But many will end missing school while they deal with a nationwide epidemic. According to research presented at the American Chemical Society’s National Annual Meeting, head lice have developed a high level of resistance to the most common over-the-counter treatments in 25 states.

Researchers from Southern Illinois University found that out of 109 head lice populations in 30 states, 104 had high levels of gene mutations causing the lice to be resistant to permethrin, the active ingredient in the most common head lice treatment products found in drug stores.

Tiny SquirrelPersonally I’m not a fan of putting chemicals on my kids’ heads so I follow the old rule, “they can’t mate with broken legs.” Regular combing with a nit comb will break the legs of a stray louse, comb out eggs  and will prevent an infestation. Once you have them, combing removes their eggs. Using hair conditioner, or the old Italian treatment of smothering with olive oil, is a good natural remedy, too. Sadly, school districts tend to like you to use permethrin. The good news is that it’s poorly absorbed by mammals and human skin, the bad news is that Canadian research suggests pyrethroids may be associated with behavior problems in children.

Regular combing will take out adults, larvae and eggs that transfer during the day, and will stop an infestation before it takes hold.
Regular combing will take out adults, larvae and eggs that transfer during the day, and will stop an infestation before it takes hold.

Lice populations in at least 25 US states have developed resistance to traditional treatments commonly used by doctors, parents and schools, scientists warn.


  • Avoid sharing combs, brushes, towels, hats and helmets
  • Don’t go head to head – try to avoid touching hairs and heads with other kids when hugging hello or goodbye
  • Keep hats, scarves and coats out of common areas
  • Selfies are fun, but can help spread lice! Taking a selfie is part of hanging out, but if it involves more than one person squeezing into a frame and connecting heads you might want your kid to opt out or go solo
  • States that follow the CDC recommendations say you can return to school as soon as you have received chemical treatment for the lice


  • Head lice spread by crawling; they cannot jump, fly or hop
  • Head to head contact with a person who has head lice is the most common way to transfer lice
  • Dogs, cats and other pets cannot contract or spread lice
  • Over the counter chemical lice pesticide treatments and shampoos are no longer effective on killing many strains of head lice
  • Head lice love all types of hair. They are not the result of bad hygiene and prefer clean rather than dirty hair

“What we found was that 104 out of the 109 lice populations we tested had high levels of gene mutations, which have been linked to resistance to pyrethroids,” Dr. Kyong Yoon of Southern Illinois University said, adding that his team is the first to collect lice samples from a large number of populations across the US.

Pyrethroids are a family of synthetic chemicals with insect repellent properties. Permethrin, which also belongs to pyrethroids, is an active ingredient in some of the most common lice treatments, such as lotions and sprays, sold at drug stores. The bugs are spread by head-to-head contact and are notoriously common among primary school kids.

According to Yoon, the momentum toward pyrethroid-resistant lice has been mounting for years, with the first report coming from Israel in the late 1990s. In 2000, when Yoon was a graduate student at the University of Massachusetts, he became one of the first to report the phenomenon in America.

“I was working on insecticide metabolism in a potato beetle when my mentor, John Clark, suggested I look into the resurgence of head lice,” he said in a press release.

“I asked him in what country and was surprised when he said the US.”

Yoon contacted schools near the university to collect samples. He imagined that the lice had probably already developed resistance to the most common insecticides aimed at combating nasty bugs. So he decided to test the pests for a trio of genetic mutations known as kdr (knock-down resistance). Yoon found that many of the lice did as a matter of fact have those kdr mutations, which affect a bug’s nervous system, desensitizing them to pyrethroids.

In his most recent study, Yoon gathered lice from as many as 30 states in America. Population samples with all three genetic mutations associated with kdr came from 25 states, including California, Texas, Florida and Maine. Samples from four states, such as New York, New Jersey, New Mexico and Oregon, had one, two or three mutations. The only state with a population of lice still largely susceptible to the insecticide was Michigan. Yoon says he is still investigating, why lice haven’t developed resistance there.

The scientist reassures that lice can still be treated using different chemicals, some of which are actually available only by prescription.

He cautioned that if you use a chemical over and over, “these little creatures will eventually develop resistance,” however. The only good news is that head lice don’t carry disease. “They’re more a nuisance than anything else,” Yoon wrapped up.