title: An ex vivo, assessor blind, randomised, parallel group, comparative efficacy trial of the ovicidal activity of three pediculicides after a single application--melaleuca oil and lavender oil, eucalyptus oil and lemon tea tree oil, and a "suffocation" pediculicide.
abstract: BACKGROUND
  There are two components to the clinical efficacy of pediculicides: (i) efficacy against the crawling-stages (lousicidal efficacy); and (ii) efficacy against the eggs (ovicidal efficacy). Lousicidal efficacy and ovicidal efficacy are confounded in clinical trials. Here we report on a trial that was specially designed to rank the clinical ovicidal efficacy of pediculicides. Eggs were collected, pre-treatment and post-treatment, from subjects with different types of hair, different coloured hair and hair of different length.
  
  
  METHODS
  Subjects with at least 20 live eggs of Pediculus capitis (head lice) were randomised to one of three treatment-groups: a melaleuca oil (commonly called tea tree oil) and lavender oil pediculicide (TTO/LO); a eucalyptus oil and lemon tea tree oil pediculicide (EO/LTTO); or a "suffocation" pediculicide. Pre-treatment: 10 to 22 live eggs were taken from the head by cutting the single hair with the live egg attached, before the treatment (total of 1,062 eggs).
  
  
  METHODS
  The subjects then received a single treatment of one of the three pediculicides, according to the manufacturers' instructions. Post-treatment: 10 to 41 treated live eggs were taken from the head by cutting the single hair with the egg attached (total of 1,183 eggs). Eggs were incubated for 14 days. The proportion of eggs that had hatched after 14 days in the pre-treatment group was compared with the proportion of eggs that hatched in the post-treatment group. The primary outcome measure was % ovicidal efficacy for each of the three pediculicides.
  
  
  RESULTS
  722 subjects were examined for the presence of eggs of head lice. 92 of these subjects were recruited and randomly assigned to: the "suffocation" pediculicide (n = 31); the melaleuca oil and lavender oil pediculicide (n = 31); and the eucalyptus oil and lemon tea tree oil pediculicide (n = 30 subjects). The group treated with eucalyptus oil and lemon tea tree oil had an ovicidal efficacy of 3.3% (SD 16%) whereas the group treated with melaleuca oil and lavender oil had an ovicidal efficacy of 44.4% (SD 23%) and the group treated with the "suffocation" pediculicide had an ovicidal efficacy of 68.3% (SD 38%).
  
  
  CONCLUSIONS
  Ovicidal efficacy varied substantially among treatments, from 3.3% to 68.3%. The "suffocation" pediculicide and the melaleuca oil and lavender oil pediculicide (TTO/LO) were significantly more ovicidal than eucalyptus oil and lemon tea tree oil pediculicide (EO/LTTO) (P < 0.0001). Ranking: 1. "Suffocation" pediculicide (68.3% efficacy against eggs); 2. Melaleuca oil and lavender oil (44.4%) pediculicide; 3. Eucalyptus oil and lemon tea tree oil (3.3%) pediculicide. The "suffocation" pediculicide and TTO/LO are also highly efficacious against the crawling-stages. Thus, the "suffocation" pediculicide and TTO/LO should be recommended as first line treatments.
authors.affiliation: Parasitology Section, School of Chemistry & Molecular Biosciences, and UniQuest Pty Ltd, University of Queensland, Brisbane, QLD, Australia. s.barker@uq.edu.au
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Barker
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Altman
mesh_terms: D000179:Acrylates / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D019905:Benzyl Alcohol / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D004338:Drug Combinations; D005021:Ethylamines / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D005052:Eucalyptus; D000078122:Eucalyptus Oil; D006601:Hexoses / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D007306:Insecticides / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D027523:Lavandula; D031649:Leptospermum; D010373:Lice Infestations / Q000188:drug therapy* / Q000469:parasitology; D031650:Melaleuca; D008899:Mineral Oil / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D039821:Monoterpenes / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D009822:Oils, Volatile / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D010063:Ovum / Q000187:drug effects* / Q000254:growth & development; D010374:Pediculus / Q000187:drug effects* / Q000254:growth & development; D008517:Phytotherapy; D010938:Plant Oils / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D011136:Polysorbates / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D012536:Scalp Dermatoses / Q000188:drug therapy* / Q000469:parasitology; D020947:Tea Tree Oil / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D000179:Acrylates; D004338:Drug Combinations; D005021:Ethylamines; C511306:Eucalyptus terpene oil; D006601:Hexoses; D007306:Insecticides; D039821:Monoterpenes; D009822:Oils, Volatile; D010938:Plant Oils; D011136:Polysorbates; C018665:sorbitan monooleate; D000078122:Eucalyptus Oil; D020947:Tea Tree Oil; D008899:Mineral Oil; C453622:carbopol 934P; D019905:Benzyl Alcohol; C016162:triethylamine; C045718:lavender oil