Chapter 15 Resistance Management of the Human Head Louse Using Molecular Tools

摘要

Head lice resistance to permethrin is mainly conferred by the knockdown resistance (kdr) trait, a voltage-sensitive sodium channel (VSSC) insensitivity factor. Three VSSC mutations have been identified and confirmed to reduce the sensitivity of VSSC to permethrin. A step-wise resistance monitoring system has been established based on molecular resistance detection techniques. Quantitative sequencing (QS) has been developed to predict the kdr allele frequency in head lice at a population basis. The speed, simplicity and accuracy of QS made it an ideal candidate for a routine primary resistance monitoring tool to screen a large number of wild louse populations as an alternative to conventional bioassay. As a secondary monitoring method, real-time PASA (rtPASA) has been devised for more precise determination of low resistance allele frequencies. To obtain more detailed information on resistance allele zygosity, as well as allele frequency, serial invasive signal amplification reaction (SISAR) has been developed as an individual genotyping method. Our approach of using three tiers of molecular resistance detection should facilitate large-scale routine resistance monitoring of permethrin resistance in head lice using field-collected samples.