title: A Chlorfenapyr Mixture Net Interceptor® G2 Shows High Efficacy and Wash Durability against Resistant Mosquitoes in West Africa.
abstract: BACKGROUND
  Malaria control through use of long-lasting insecticidal nets (LN) is threatened by the selection of anopheline mosquitoes strongly resistant to pyrethroid insecticides. To sustain future effectiveness it is essential to identify and evaluate novel insecticides suitable for nets. Mixtures of two insecticides with contrasting mode of action have the potential to kill resistant vectors and restore transmission control provided the formulation can withstand regular washing over the net's life span.
  
  
  METHODS
  The efficacy of a novel mixture LN, Interceptor® G2, that combines the pyrrole chlorfenapyr and pyrethroid alpha-cypermethrin was evaluated under controlled household conditions (experimental hut trial) and by laboratory bioassay against pyrethroid resistant An. gambiae in Benin before and after standardized washing. Comparison arms included standard alpha-cypermethrin LN, nets hand-treated with chlorfenapyr-only and untreated nets.
  
  
  RESULTS
  The chlorfenapyr-alphacypermethrin LN demonstrated improved efficacy and wash resistance compared to a standard alpha-cypermethrin LN against pyrethroid resistant mosquitoes (resistance ratio 207). In experimental hut trial alpha-cypermethrin LN killed only 20% (95% CI 15-26%) of host-seeking An. gambiae whilst mixture LN killed 71% (95% CI 65-77%). Mixture LN washed 20 times killed 65% (95% CI 58-71%), and thus intensive washing reduced efficacy by only 6% (95% CI 1.3-11%). The chlorfenapyr net killed 76% (95% CI 70-81%). Personal protection and blood feeding inhibition did not differ between mixture and pyrethroid LN; however, the mixture LN was 2.5 (95% CI: 2.1-3.1) times more protective than untreated nets. Standard WHO cone bioassays conducted during day time hours failed to anticipate field efficacy but overnight tunnel tests successfully predicted mixture LN and chlorfenapyr net efficacy in field trials.
  
  
  CONCLUSIONS
  Interceptor® G2 LN demonstrates the potential to control transmission and provide community protection over the normal lifespan of long lasting nets where standard pyrethroid LN show signs of failing due to resistance.
authors.affiliation: London School of Hygiene and Tropical Medicine, London, United Kingdom.|Centre de Recherche Entomologique de Cotonou, Ministry of Health, Cotonou, Benin.|Pan-African Malaria Vector Research Consortium (PAMVERC), London, United Kingdom.
authors.forename: Raphael
authors.initials: R
authors.lastname: N'Guessan
authors.affiliation: Centre de Recherche Entomologique de Cotonou, Ministry of Health, Cotonou, Benin.
authors.forename: Abibatou
authors.initials: A
authors.lastname: Odjo
authors.affiliation: London School of Hygiene and Tropical Medicine, London, United Kingdom.|Centre de Recherche Entomologique de Cotonou, Ministry of Health, Cotonou, Benin.|Pan-African Malaria Vector Research Consortium (PAMVERC), London, United Kingdom.
authors.forename: Corine
authors.initials: C
authors.lastname: Ngufor
authors.affiliation: Innovative Vector Control Consortium, Liverpool, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Malone
authors.affiliation: London School of Hygiene and Tropical Medicine, London, United Kingdom.|Pan-African Malaria Vector Research Consortium (PAMVERC), London, United Kingdom.
authors.forename: Mark
authors.identifier: http://orcid.org/0000-0002-5567-9562
authors.initials: M
authors.lastname: Rowland
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects*; D001541:Benin; D001681:Biological Assay; D004351:Drug Resistance / Q000187:drug effects*; D005247:Feeding Behavior / Q000187:drug effects; D057148:Insecticide-Treated Bednets; D007306:Insecticides / Q000494:pharmacology; D009032:Mosquito Control; D011722:Pyrethrins / Q000494:pharmacology*; D014944:World Health Organization
chemical_list: D007306:Insecticides; D011722:Pyrethrins; C017160:cypermethrin; C436643:chlorfenapyr