Lice are becoming more difficult to eradicate in young children’s hair, according to a study released last week in the Journal of Medical Entomology (JME).
New evidence shows that head lice have developed resistance to two types of common over the counter insecticide treatments for lice infestation. JME studied 48 states and found that, on average, 98 percent of head lice in at least 42 states managed to grow gene mutations that enable them to become resistant to different insecticides otherwise known as pyrethrins, pyrethroids, and permathrins. …
Parapro.com notes in its timeline that the first natural pyrethrins to treat lice happened in 1945. By the 1980s, the over-the-counter insecticide solution to treat lice known as Nix, a permathrin, was the most commonly used treatment and was “nearly 100 percent effective.”
In 2009, Nix is now only 25 percent effective and by 2015, Parapro writes, “The three pyrethrin- and pyrethroid-resistant gene mutations are observed in an average of 98% of lice gathered from 48 states.”