Lice resistance research

Two new papers on the response of lice and nits to common treatments have recently been published.

The papers, published in the March 2014 edition of Journal of Medical Entomology, discuss the spread of genetic resistance to pymethrin treatments, and the efficacy of nit-removal treatments in human hair.

Genetic resistance to pymethrin increases

Kyong Sup Yoon et al., investigated the spread and frequency of the genetic mutation which confers pymethrin resistance on head lice.

Samples of lice from 32 North American locations were analysed, showing that 88% of them contained the resistance-conferring mutation. This is in line with previous studies showing the resistance-conferring mutation in well above 80% of the lice population, and provides further evidence for the need for alternative treatment methods.

Better nit removal still an unsolved problem

A study in the same edition of the Journal, by Lapeere et al. looked at the ability of common lice treatment products to remove nits from hair.

The study concluded that water and ordinary hair conditioner "significantly facilitated" removal of nits in the tests, and there was no discernable difference between these products and specialist products marketed for the purposes of nit removal.