title: Determination of knockdown resistance allele frequencies in global human head louse populations using the serial invasive signal amplification reaction.
abstract: BACKGROUND
  Pediculosis is the most prevalent parasitic infestation of humans. Resistance to pyrethrin- and pyrethroid-based pediculicides is due to knockdown (kdr)-type point mutations in the voltage-sensitive sodium channel alpha-subunit gene. Early detection of resistance is crucial for the selection of effective management strategies.
  
  
  RESULTS
  Kdr allele frequencies of lice from 14 countries were determined using the serial invasive signal amplification reaction. Lice collected from Uruguay, the United Kingdom and Australia had kdr allele frequencies of 100%, while lice from Ecuador, Papua New Guinea, South Korea and Thailand had kdr allele frequencies of 0%. The remaining seven countries investigated, including seven US populations, two Argentinian populations and populations from Brazil, Denmark, Czech Republic, Egypt and Israel, displayed variable kdr allele frequencies, ranging from 11 to 97%.
  
  
  CONCLUSIONS
  The newly developed and validated SISAR method is suitable for accurate monitoring of kdr allele frequencies in head lice. Proactive management is needed where kdr-type resistance is not yet saturated. Based on sodium channel insensitivity and its occurrence in louse populations resistant to pyrethrin- and pyrethroid-based pediculicides, the T917I mutation appears to be a key marker for resistance. Results from the Egyptian population, however, indicate that phenotypic resistance of lice with single or double mutations (M815I and/or L920F) should also be determined.
authors.affiliation: Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Hilliary E
authors.initials: HE
authors.lastname: Hodgdon
authors.forename: Kyong Sup
authors.initials: KS
authors.lastname: Yoon
authors.forename: Domenic J
authors.initials: DJ
authors.lastname: Previte
authors.forename: Hyo Jeong
authors.initials: HJ
authors.lastname: Kim
authors.forename: Gamal E
authors.initials: GE
authors.lastname: Aboelghar
authors.forename: Si Hyeock
authors.initials: SH
authors.lastname: Lee
authors.forename: J Marshall
authors.initials: JM
authors.lastname: Clark
mesh_terms: D000818:Animals; D001483:Base Sequence; D004252:DNA Mutational Analysis / Q000379:methods*; D004351:Drug Resistance / Q000235:genetics*; D005787:Gene Frequency; D049750:Genome, Insect / Q000235:genetics; D038622:Internationality; D008969:Molecular Sequence Data; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D010374:Pediculus / Q000187:drug effects / Q000235:genetics*; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D015203:Reproducibility of Results; D015222:Sodium Channels / Q000235:genetics
chemical_list: D015222:Sodium Channels