Permethrin resistance in the head louse Pediculus capitis from Israel

Abstract

Head lice, Pediculus capitis, were collected from children aged 3-12 years in Maale Adumin, a town near Jerusalem, after reports of control failure with the pyrethroid insecticide permethrin. A total of 1516 children were examined: living lice and eggs were found on 12.1% of the children; or another 22.8% of the children only nits were found. Twice as many girls as boys (8.1% v 4%) were infested with lice and or nits. Head lice collected from infested children were exposed to permethrin impregnated filter-papers. Log time probit mortality (ltp) regression lines were calculated for mortality data and compared to ltp lines for a similar collection of head lice made in 1989. The regression lines for the two years were significantly different, with a 4-fold decrease in susceptibility at the LT50 level between 1989 and 1994. The slopes of the lines also suggested that the 1994 population was more heterogenous in its response to permethrin than the 1989 population. In contrast, a laboratory population of body lice (Pediculus humanus) tested with the same batch of permethrin-impregnated papers showed a slight but non-significant increase in susceptibility between 1989 and 1994. The results suggest that resistance to pyrethroids has developed rapidly among head lice since permethrin was introduced in 1991 as a pediculicide in Israel.

Head Lice

“…8,30 An alternate treatment schedule on days 0, 7, and 13 to 15 has been proposed for nonovicidal products. 31 Resistance to 1% permethrin has been reported, 8,[32][33][34][35] but the prevalence of this resistance is not known. .…”

Three mutations identified in the voltage-sensitive sodium channel α-subunit gene of permethrin-resistant human head lice reduce the permethrin sensitivity of house fly Vssc1 sodium channels expressed in Xenopus oocytes

“…Over the last two decades, resistance to pyrethrins and pyrethroid insecticides by the human head louse, Pediculus humanus capitis, has been widely documented (Burgess et al, 1995;Downs et al, 1999a;Downs et al, 1999b;Chosidow et al, 1994;Mumcuoglu et al, 1995;Hemingway et al, 1999;Rupes et al, 1995;Picollo et al, 1998;Vassena et al, 2003;Yoon et al, 2003;Yoon et al, 2004;Lee et al, 2000b). Heightened public and governmental concerns have occurred because of increased incidents of head louse infestations among school children (http://www.cdc.gov/ncidod/dpd/parasites/lice/default.htm; http://www.headlice.org).…”

Comparative In Vitro Pediculicidal Efficacy of Treatments in a Resistant Head Lice Population in the United States

“…[1][2][3] The most likely targets are school-aged children between 3 and 11 years [2][3][4] and their immediate contacts (such as day care providers, family members, and playmates). In the United States, families spend more than $160 million annually on head lice treatments purchased from pharmacies and supermarkets.…”