Treatment-resistant lice have been reported in 25 states, just in time for the start of the school year.
Details on the mutant lice, which have appeared to develop a resistance to over-the-counter treatments, were
released by the American Chemical Society in Boston this week.
"We are the first group to collect lice samples from a large number of populations across the U.S.," said Kyong Yoon, with Southern Illinois University, 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."
Pyrethroids are widely used to control mosquitoes and other insects. The chemical includes permethrin, the active ingredient in some of the most common over-the-counter lice treatments, said the society.
The first report of mutated lice came in the late 1990s in Israel. They were found in the United States in 2000, said Yoon.
The
Centers for Disease Control and Prevention say lice infest the head and neck areas, attaching their eggs to the base of the hair shaft. Lice infestation is spread most commonly by close person-to-person contact since the bugs cannot fly or hop.
The CDC website says family pets, such and dogs and cats, do not play a role in human lice transmission.
The
Washington Post reported that three different mutations affect the parasite's nervous system and makes them less sensitive to the insecticide chemicals that are found in common lice treatments.
"If you use a chemical over and over, these little creatures will eventually develop resistance," said Yoon. "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."
Population samples with all three genetic mutations came from 25 states.
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