New mutant head lice resistant to common treatments

The team gathered lice samples from 30 states and found that 25 states had lice with genetic mutations called “knock-down resistance” mutations that have been known to help certain insects, including house flies, survive insecticides. Why lice haven’t developed resistance there is still under investigation, researchers say.

“If you use a chemical over and over, these little creatures will eventually develop resistance”, Yoon says.

Permethrin, the active ingredient in some of the most common lice treatments sold over the counter, is present in them.

“Some kids may have an underlying health condition, like asthma, where they couldn’t tolerate all the treatments”, she said.

So what are parents to do?

If you’ve picked off every louse in site and the lice won’t die or they come back, a doctor can prescribe a shampoo with stronger chemicals that should be effective with resistant lice. The samples from Texas, California, Maine and Florida had the three genetic mutations and thus made them the most resistant states to pyrethroids.

Now super lice are invading 25 states including all four of our Heartland states.

New research shows lice populations in some states have developed high resistance to treatment. In 2000, Yoon became one of the first researchers to report the development in the US, when he was still a graduate student at the University of Massachusetts.

She said she has seen more lice cases from teenagers and young adults, attributing some instances to posing for pictures and “selfies” where heads are touching.

But over time, they could be at risk of the same problem as lice populations continue to evolve, cautions Yoon.

Of the 109 lice populations tested, 104 had high levels of the gene mutations.

To prevent head lice from mutating again the future, said Clark, there need to be a number of anti-lice products on the market at the same time, so that lice can’t select against one particular mutation, the way they did with pyrethroids.

“I think it’s disappointing, but not surprising”, said Dr. Nicholas Bennett, medical director for Infectious Diseases and Immunology at the Connecticut Children’s Medical Center. They say leaning into pictures to take a “selfie” has been a rising culprit of spreading the infestation among teens.