Treatment-Resistant Lice Found In California, 24 Other States

(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. In the latest study, researchers found lice with three genetic mutations in 25 states, including California, Texas, Florida and Maine that make them resistant to common treatments.

The American Academy of Pediatrics advises that in areas with known resistance to an over-the-counter treatment, "parents should involve their pediatrician for treatment with a prescription medication such as spinosad or topical ivermectin."

For more on how the mutations may change the way head lice is treated, visit CBSnews.com.