Control and Resistance Management of Human Pediculosis

摘要

Head louse resistance to commonly used pediculicides is wide spread worldwide. Resistance to permethrin and pyrethrum is 40- to 70-fold based on tolerance to knockdown response in US populations of head louse. Resistance to malathion is likewise widespread but at lower levels (2.0- to 3.3-fold). Currently, there appears to be little or no resistance to abamectin or lindane. Permethrin-resistant head lice are significantly more tolerant to knockdown and are cross-resistant to DDT, indicating a Mr-type of resistance mechanism. Sequence analysis of the full-length cDNA fragments of voltage-sensitive sodium channel α-subunit gene from permethrin-resistant head louse populations has identified three mutations (M815I, T917I, and L920F). All these mutations appear to exist en bloc as a haplotype and have functional significances in resistance. We have developed DNA-diagnostic protocols, including serial invasive signal amplification reaction (SISAR), for the detection of the conserved point mutations resulting in knockdown resistance to the pyrethrins, the pyrethroids, and DDT. A sound resistance management strategy based on efficient DNA-based genotyping techniques will greatly expand the lifespan of the valuable and effective pediculicides, such as permethrin, and ensure safe control of pediculosis.