RT Journal
A1 Pollack RJ, Kiszewski A, Armstrong P, et al
T1 DIfferential permethrin susceptibility of head lice sampled in the united states and borneo
JF Archives of Pediatrics & Adolescent Medicine
JO Archives of Pediatrics & Adolescent Medicine
YR 1999
FD September 1
VO 153
IS 9
SP 969
OP 973
DO 10.1001/archpedi.153.9.969
UL http://dx.doi.org/10.1001/archpedi.153.9.969
AB Background 
    Pediculiasis is treated aggressively in the United States, mainly with permethrin- and pyrethrin-containing pediculicides. Increasingly frequent anecdotal reports of treatment failure suggest the emergence of insecticidal resistance by these lice.Objective 
    To confirm or refute the susceptibility of head lice sampled in the United States to permethrin.Design 
    Survey. Head lice were removed from children residing where pediculicides are readily available and where such products are essentially unknown. Their survival was compared following exposure to residues of graded doses of permethrin in an in vitro bioassay.Setting 
    School children from Massachusetts, Idaho, and Sabah (Malaysian Borneo).Subjects 
    In the United States, 75 children aged 5 to 8 years. In Sabah, 59 boys aged 6 to 13 years. Virtually all sampled US children had previously been treated with pediculicides containing pyrethrins or permethrin; none of the Sabahan children were so exposed.Main Outcome Measure 
    Survival of head lice exposed to permethrin.Results 
    Permethrin did not affect head lice sampled from chronically infested US children who had previously been treated for pediculiasis. The slope of the dose-response regression line for these lice did not differ significantly from zero (P=.66). This pediculicide immobilized lice sampled in Sabah. Mortality correlated closely with permethrin concentration (P=.008).Conclusions 
    Head lice in the United States are less susceptible to permethrin than are those in Sabah. The pyrethroid susceptibility of the general population of head lice in the United States, however, remains poorly defined. Accordingly, these relatively safe over-the-counter preparations may remain the pediculicides of choice for newly recognized louse infestations.