(CBS News) – Head lice are a giant nuisance — as many as 12 million American school children between the ages of 3 and 11 get them each year, according to the Centers for Disease Control and Prevention. And to make matters worse, researchers continue to find evidence that the tiny pests are becoming genetically resistant to common treatments that people use to battle the bugs.
A new study finds that lice in at least 25 states have developed resistance to an ingredient found in over-the-counter remedies that are widely recommended by doctors and school officials. The research is being presented Tuesday at a meeting of the American Chemical Society (ACS).
Researchers from Southern Illinois University gathered lice samples from 30 states, with the help of a network of public health workers.
“We are the first group to collect lice samples from a large number of populations across the U.S.,” explained Kyong Yoon, Ph.D., in a press release. “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.”