A 2015 study reported that most head lice found in North America now carry a gene mutation that makes them resistant to standard over-the-counter lice-removal products.
They are called super lice, and evidence suggests they are pretty much everywhere.
Kyong Yoon, Ph.D., a researcher at Southern Illinois University, presented his team’s findings at the 250th National Meeting & Exposition of the American Chemical Society (ACS), the world’s largest scientific society. The meeting features more than 9,000 presentations on a wide range of science topics.
“We are the first group to collect lice samples from a large number of populations across the U.S.,” Yoon said “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.”
Pyrethroids are a family of insecticides used widely indoors and outdoors to control mosquitoes and other insects. The Pyrethroid family includes Permethrin, the active ingredient in some of the most common lice treatments sold at drug stores.
“If you use a chemical over and over, these little creatures will eventually develop resistance,” Yoon said. “So we have to think before we use a treatment.”
Pyrethroids are neurotoxins—they lock onto receptors in insect nervous systems, paralyzing and eventually killing them.
Another study led by John Clark, a professor of environmental toxicology and chemistry at the University of Massachusetts Amherst, published in the Journal of the Entomological Society of America, found that 99.6 percent of head lice tested in 2007-09 were genetically resistant to Pyrethroids. “In the UK and Europe, they don’t even use Pyrethroids anymore. Virtually everyone but the United States and Canada has given up using these over-the-counter products,” Clark said.
Dr. Eric Ayers, an assistant professor of internal medicine and pediatrics with the Wayne State University Physicians Group and the Children’s Hospital of Michigan says that resistance can develop quickly. He found that if the lice medication isn’t effective the first time it is applied, “the lice can not only survive, but grow stronger. They’re then able to tolerate that same medication the next time it is applied. Then, those more-resistant bugs can move from the head of one child to another, spreading super lice.”
Some have questioned the use of Pyrethroids in the battle against head lice, even when they were effective. Deborah Altschuler, the president of the National Pediculosis Association, a nonprofit group that advocates on head-lice issues, has long urged parents not to use pesticides on children. She said she has collected more than 1,000 reports dating from the 1980s from worried parents who ask about research that links the products to seizures, behavioral problems and leukemia. She said the fact that parents are led to pesticides as a first line of defense against head lice “puts children and entire families in jeopardy.”
For parents worried about the safety and effectiveness of pesticide-based head lice treatment, there is an alternative. Researchers at the University of Utah have developed a medical device that kills head lice and lice eggs, or nits. It uses nothing more than carefully controlled warm air to dehydrate lice and eggs.
It’s called AirAllé. It represents a completely new approach to head-lice removal. The device has been through clinical trials and has been cleared by the FDA as safe and effective for lice removal, killing both live lice and 99.2 percent of eggs in a single treatment.
Because it doesn’t rely on pesticides, the AirAllé device is just as effective against so-called super lice as it is against non-resistant head lice. The treatment is pesticide-free and there are no known side effects.
The culmination of the University of Utah researchers’ work was published in 2006 in the journal Pediatrics. A follow-up study was published in the Journal of Medical Entomology in 2011.
The AirAllé device is available exclusively at Lice Clinics of America treatment centers where trained technicians use the device to remove head lice in a single 60- to 90-minute treatment.