Advertisement  

August 27, 2015
Bad News for Schoolchildren: Lice Resistant to
Many OTC Treatments

Edwardsville, IL—It’s that time a year again when nervous-looking parents pull pharmacists aside and desperately ask the question: What can I do about my child’s head lice?

According to where the pharmacy is located, parents might have to brace themselves for some bad news—lice populations in at least 25 states have developed resistance to OTC treatments still widely recommended by pharmacists, other healthcare professionals, and schools.

That’s according to a recent presentation at the 250th National Meeting & Exposition of the American Chemical Society (ACS), the world’s largest scientific society. A study led by researchers from Southern Illinois University in Edwardsville tested resistance to pyrethroids, a family of insecticides used indoors and out to control mosquitoes and other insects. Among those insecticides is permethrin, the active ingredient in some common lice-fighting treatments.

“We are the first group to collect lice samples from a large number of populations across the U.S.,” explained lead researcher Kyong Yoon, PhD of Southern Illinois University in Edwardsville. “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.”

The resistance has been building for years, according to Yoon, who said the first resistance report came from Israel in the late 1990s.

For this study, he gathered lice from 30 states with the help of a broad network of public health workers. Population samples including a trio of genetic mutations—which affect insects’ nervous system and desensitize them to pyrethroids—came from 25 states, including California, Texas, Florida, and Maine. Having all the mutations, known collectively as knock-down resistance (kdr), means these populations are the most resistant to pyrethroids. Resistance was especially prevalent in the South and the Midwest, according to the report. A map can be viewed here.

Samples from four states—New York, New Jersey, New Mexico, and Oregon—had one, two, or three mutations. Interestingly, Michigan was the only state with a population of lice still largely susceptible to the insecticide, something Yoon said is still under investigation.

Pointing out that lice can still be controlled by using different chemicals, some of which are available only by prescription, Yoon said in an ACS press release that the situation creates a cautionary tale. “If you use a chemical over and over, these little creatures will eventually develop resistance,” he noted. “So we have to think before we use a treatment. The good news is head lice don't carry disease. They're more a nuisance than anything else.”




Connect With U.S. Pharmacist
USP Google AppUSP Itunes App