(SEEKER) — The vast majority of head lice in the United States are now resistant to most over-the-counter treatments, meaning that it's now especially difficult to vanquish the tiny blood-sucking parasites, a new study finds.
Researchers found that head lice (Pediculus humanus capitis) in 42 of the 48 states studied carry an average of three genetic mutations that make these bugs impervious to popular over-the-counter anti-lice remedies. In the remaining six states, the lice had zero, one or two of the three mutations, on average, the researchers reported in the study, published online March 31 in the Journal of Medical Entomology.
Moreover, a detailed analysis showed that 98.3 percent of the genes involved in these mutations were, in fact, mutated in a way that helped the lice survive the most popular treatments, the researchers found.
Advertisement - story continues below