title: Evaluation of PermaNet 3.0 a deltamethrin-PBO combination net against Anopheles gambiae and pyrethroid resistant Culex quinquefasciatus mosquitoes: an experimental hut trial in Tanzania.
abstract: BACKGROUND
  Combination mosquito nets incorporating two unrelated insecticides or insecticide plus synergist are designed to control insecticide resistant mosquitoes. PermaNet 3.0 is a long-lasting combination net incorporating deltamethrin on the side panels and a mixture of deltamethrin and synergist piperonyl butoxide (PBO) on the top panel. PBO is an inhibitor of mixed function oxidases implicated in pyrethroid resistance.
  
  
  METHODS
  An experimental hut trial comparing PermaNet 3.0, PermaNet 2.0 and a conventional deltamethrin-treated net was conducted in NE Tanzania using standard WHOPES procedures. The PermaNet arms included unwashed nets and nets washed 20 times. PermaNet 2.0 is a long-lasting insecticidal net incorporating deltamethrin as a single active.
  
  
  RESULTS
  Against pyrethroid susceptible Anopheles gambiae the unwashed PermaNet 3.0 showed no difference to unwashed PermaNet 2.0 in terms of mortality (95% killed), but showed differences in blood-feeding rate (3% blood-fed with PermaNet 3.0 versus 10% with PermaNet 2.0). After 20 washes the two products showed no difference in feeding rate (10% with 3.0 and 9% with 2.0) but showed small differences in mortality (95% with 3.0 and 87% with 2.0). Against pyrethroid resistant Culex quinquefasciatus, mediated by elevated oxidase and kdr mechanisms, the unwashed PermaNet 3.0 killed 48% and PermaNet 2.0 killed 32% but after 20 washes there was no significant difference in mortality between the two products (32% killed by 3.0 and 30% by 2.0). For protecting against Culex PermaNet 3.0 showed no difference to PermaNet 2.0 when either unwashed or after 20 washes; both products were highly protective against biting. Laboratory tunnel bioassays confirmed the loss of biological activity of the PBO/deltamethrin-treated panel after washing.
  
  
  CONCLUSIONS
  Both PermaNet products were highly effective against susceptible Anopheles gambiae. As a long-lasting net to control or protect against pyrethroid resistant mosquitoes PermaNet 3.0 showed limited improvement over PermaNet 2.0 against Culex quinquefasciatus.
authors.affiliation: Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania.
authors.forename: Patrick
authors.initials: P
authors.lastname: Tungu
authors.forename: Stephen
authors.initials: S
authors.lastname: Magesa
authors.forename: Caroline
authors.initials: C
authors.lastname: Maxwell
authors.forename: Robert
authors.initials: R
authors.lastname: Malima
authors.forename: Dennis
authors.initials: D
authors.lastname: Masue
authors.forename: Wema
authors.initials: W
authors.lastname: Sudi
authors.forename: Joseph
authors.initials: J
authors.lastname: Myamba
authors.forename: Olivier
authors.initials: O
authors.lastname: Pigeon
authors.forename: Mark
authors.initials: M
authors.lastname: Rowland
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects*; D003465:Culex / Q000187:drug effects*; D004351:Drug Resistance; D005247:Feeding Behavior / Q000187:drug effects; D006801:Humans; D057148:Insecticide-Treated Bednets; D007306:Insecticides / Q000494:pharmacology*; D009032:Mosquito Control / Q000379:methods*; D009570:Nitriles / Q000494:pharmacology*; D010882:Piperonyl Butoxide / Q000494:pharmacology*; D011722:Pyrethrins / Q000494:pharmacology*; D016019:Survival Analysis; D013636:Tanzania
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin; D010882:Piperonyl Butoxide