Lice With Drug-Resistant Mutations Found to Be Widespread in US, But Experts Say Don't Panic

PHOTO: This 2006 photograph depicts a dorsal view of a female body louse, Pediculus humanus var. corporis. PlayJames Gathany/Getty Images
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Researchers say they have found what every parent fears before the start of the school year: mutated lice that may be resistant to common treatments. But experts are cautioning against a panic, saying these results are preliminary.

Kyong Yoon, an assistant professor at Southern Illinois University, and John Marshall Clark, director of the Massachusetts Pesticide Analysis Laboratory and professor at the University of Massachusetts, presented preliminary findings from their study on mutant lice at a meeting of the American Chemical Society (ACS) in Boston on Tuesday.

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.

"If you use a chemical over and over, these little creatures will eventually develop resistance,” Yoon said in a statement. “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.”

The specific mutations have been shown in other insects to protect them from common insecticides, including the chemicals used in common over-the-counter treatment for lice.

However, the team did not study if the lice with the mutations actually survived over-the-counter treatments in practice. They did study if there has been a reported rise in drug-resistant lice in the affected states. The team plans to look at lice in at least 48 states before publishing the results.

At least one expert said the findings were interesting but that it was too preliminary to say for sure that the mutant lice are also drug resistant and causing a widespread problem.

Dr. Joseph Gigante, a pediatrician at Vanderbilt University Medical Center, said more study was needed to see if these lice are actually drug resistant to common over-the-counter medication.

"We see it with antibiotics that in the lab test tube it's resistant, [but] if you treat them with the medicine you see a response," Gigante said of other studies that are focused in the lab.

However, he said he's eager to see more study in the area and that anecdotally he's seen more patients who have stubborn cases of lice even after two or three over-the-counter treatments.

"The message I would share is that don’t panic and catch your breath," said Gigante, who said he would tell patients to "treat with over-the-counter medicines more than once."

Gigante pointed out that lice are annoying and itchy but that they don't spread disease.

"Your child is not going to get sick. There’s a lot of social stigma with this," Gigante said. "It truly is more of a nuisance."

He said even if the lice seem resistant after a few treatments with over-the-counter drugs, there are prescription therapies as well, but they are generally more costly. There is also a chance that parents aren't appropriately treating lice the first time or that the insects return if they infected a favorite hat or headband, he said.

"If they're using things like headbands or hats, they can spread it from one child to another," he said. "It can also be a potential reason why they're not getting better."