02234nas a2200253   4500008004100000245009400041210006900135260000900204300001400213490000700227520150100234653001301735653001201748653001201760653001401772653001401786653001501800653001501815100002401830700001701854700002601871700002701897856005601924       2006                        eng d00aSurvey of Permethrin and Malathion Resistance in Human Head Lice Populations from Denmark0 aSurvey of Permethrin and Malathion Resistance in Human Head Lice  c2006  a533 - 5380 v433 aHead lice, Pediculis capitis De Geer, populations were investigated for permethrin and malathion resistance after initial establishment of a discriminating dose of topical application bioassay with body lice, Pediculus humanus L. For both insecticides, ≈2 times the lethal dose (LD)95 at 4 h was selected, 2 ng of permethrin and 100 ng of malathion per head louse, respectively. Head lice were collected from heads of infested children in Denmark at 33 primary schools, one kindergarten, and seven boarding schools. The lice were collected by combing of dry hair, with a fine-toothed antilouse comb attached to a vacuum cleaner. A resistance survey covers head lice collected from 208 of 1,441 persons combed. The frequency of permethrin- and malathion-resistant head lice is high in Danish head lice populations. In 17 of 24 samples tested for permethrin resistance, all head lice survived the discriminating dose. Six samples had between 3 and 25% dead head lice, whereas one sample had 60% mortality. In nine of 25 samples tested for malathion resistance, all head lice survived the discriminating dose. Seven samples had <25% dead head lice, and four samples had a mortality of 50% or more at the discriminating dose. The connection between permethrin resistance and kdr-like mutations is confirmed by our findings. The frequency of the double mutation T929I-L932 F in the voltage-sensitive sodium channel gene associated with permethrin resistance was 0.95 in Danish head lice populations.10abioassay10acapitis10ahumanus10aknockdown10aPediculus10apyrethroid10aresistance1 aKristensen, Michael1 aKnorr, Mette1 aRasmussen, Anne-Marie1 aJespersen, Jørgen, B.  uhttp://www.phthiraptera.info/Publications/46259.pdf