Head louse pyrethroids

Sodium Channel Point Mutations Associated with Pyrethroid Resistance in the Head Louse, Pediculus humanus capitis... 

Reduced Na" channel sensitivity in pyrethroid-resistant head lice was first suggested by Hemmingway et al. (25). In pyrethroid-resistant head louse colonies from the US and the UK, resistance-specific two concomitant amino acid substitutions were commonly identified as kdr-VkQ mutations at DII S5 of para Na channel (26). Their analysis was based on a partial cDNA sequence of as many as 132 amino acid residues including Dll S3 and S6. Analysis of the whole coding sequence is a prerequisite for the development of molecular diagnosis or the study of the genetic origins of kdr-Vke mutations in head lice. 

Pyrethroid-resistance of head lice was discriminated with phenothrin at 100 mg/m by the method of continuous contact of insecticide-impregnated filter paper for 3 hours. We first identified pyrethroid-resistant head lice colonies in Japan. Pyrethroid pediculicides seemed to be out of use for the resistant colonies, however, the resistance has not been an overwhelming majority in Tokyo metropolitan area. The complete coding sequence of poru-orthologous Na channel was determined in the head louse and resistance-associated four amino acid substitutions were commonly identified in the Na channel from the three resistant colonies tested. 

In this article, the level of susceptibility to various insecticides in different human head louse populations in the US was investigated to assess the distribution of resistance. We also reported on the molecular mechanisms of head louse resistance to pyrethroid mediated by sodium channel mutations. Also discussed were the genotyping techniques for resistance monitoring and the... 

Molecular Mechanisms of Head Louse Resistance to Pyrethroids and Development of Monitoring Tools for Resistance Management... 

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