According to reports, scientists are saying that lice populations in nearly 25 states have become resistant to over-the-counter treatments that are still extensively recommended by schools and doctors. The researchers are going to represent their work at the 250th National Meeting & Exposition of the American Chemical Society (ACS), which is largest scientific society in the world.

There will be over 9,000 presentations in the meeting on a wide range of topics based on science and it is being held through Thursday.

According to Kyong Yoon, Ph.D, they have collected lice samples from a number of populations found in the US and their group is first to do so. He added that they have found that 104 out of the 109 lice populations tested by them were having high levels of gene mutations that have been associated with resistance to pyrethroids.

As per experts, pyrethroids are a group of insecticides that are used extensively indoors and outdoors in order to control mosquitoes as well as other insects. It consists of permethrin, which is the active ingredient found in some common lice treatments that are sold at drug stores.

According to him, "I was working on insecticide metabolism in a potato beetle when my mentor, John Clark, suggested I look into the resurgence of head lice. I asked him in what country and was surprised when he said the US".

It was found by Yoon that many of the lice were certainly having kdr mutations that affect nervous system of insects and makes them less sensitive to pyrethroids.