title: Laboratory and field evaluation of the impact of washings on the effectiveness of LifeNet®, Olyset® and PermaNet® 2.0 in two areas, where there is a high level of resistance of Anopheles gambiae to pyrethroids, Benin, West Africa.
abstract: BACKGROUND
  An investigation carried out in Benin has shown that, in some areas close to rivers where density of mosquitoes is high, long-lasting, insecticidal bed nets (LLINs) are permanently used. In such areas, LLINs are washed every month. Based on this situation, the 20-wash minimum efficacy advised by the manufacturers would be inadequate. The main goal of this study was to evaluate the effectiveness of LifeNet®, Olyset® and Permanet® 2.0 washed several times against Anopheles gambiae sensu stricto (s.s.) populations, which have developed high resistance to pyrethroids.
  
  
  METHODS
  Efficacy of LifeNet®, Olyset® and PermaNet® 2.0 washed 30 and 40 times was expressed in terms of blood-feeding inhibition rate, deterrence, induced exophily and mortality rates. This WHOPES phase II evaluation, conducted in experimental huts in Akron (southern Benin) and in Malanville (northern Benin), was accompanied by WHOPES Phase I evaluation.
  
  
  RESULTS
  Over 40 successive washes, LifeNet® induced a mortality rate over 80% in phase I. However, beyond 10 washes, Permanet® 2.0 and Olyset induced dramatically reduced mortality rates, respectively 12.5 and 2.5%. With regard to Phase II results, unwashed LifeNet®, LifeNet® and Olyset® washed 30 and 40 times induced a similar exophily rate per study site (at least 58% in Malanville and at least 71% in Akron). Regarding blood feeding inhibition, LifeNet® and Olyset® washed 30 and 40 times significantly reduced wild An. gambiae s.s. blood feeding showing a similar personal protection as unwashed LifeNet®. LifeNet® washed 30 and 40 times induced mortality rates significantly higher than those induced by Olyset® and Permanet® 2.0 (P < 0,05).
  
  
  CONCLUSIONS
  LifeNet®, followed by Olyset®, have shown good efficacy against host-seeking resistant An. gambiae s.s. population in experimental huts in Benin. Lifenet® have shown to be an effective and promising vector control tool to prevent malaria in areas where repeated washings is a common practice in the community.
authors.affiliation: Laboratoire Evolution, Biodiversité des Arthropodes et Assainissement, FAST, University of Abomey-Calavi, Cotonou, Bénin. rofargossa@yahoo.fr.
authors.forename: Fiacre R
authors.initials: FR
authors.lastname: Agossa
authors.forename: Gil G
authors.initials: GG
authors.lastname: Padonou
authors.forename: Virgile
authors.initials: V
authors.lastname: Gnanguenon
authors.forename: Frédéric
authors.initials: F
authors.lastname: Oké-Agbo
authors.forename: Jacques
authors.initials: J
authors.lastname: Zola-Sahossi
authors.forename: Horace
authors.initials: H
authors.lastname: Dègnonvi
authors.forename: Albert
authors.initials: A
authors.lastname: Salako
authors.forename: Michel
authors.initials: M
authors.lastname: Sèzonlin
authors.forename: Martin C
authors.initials: MC
authors.lastname: Akogbéto
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000502:physiology*; D001541:Benin; D001681:Biological Assay; D006796:Household Work; D007305:Insecticide Resistance; D057148:Insecticide-Treated Bednets; D007306:Insecticides / Q000494:pharmacology*; D011722:Pyrethrins / Q000494:pharmacology*; D016019:Survival Analysis
chemical_list: D007306:Insecticides; D011722:Pyrethrins