title: Combining organophosphate treated wall linings and long-lasting insecticidal nets for improved control of pyrethroid resistant Anopheles gambiae.
abstract: BACKGROUND
  New approaches to delivering insecticides need to be developed to improve malaria vector control. Insecticidal durable wall lining (DL) and net wall hangings (NWH) are novel alternatives to indoor residual spraying which can be produced in a long-lasting format. Non-pyrethroid versions could be used in combination with long-lasting insecticidal nets for improved control and management of insecticide resistant vector populations.
  
  
  METHODS
  Experimental hut trials were carried out in Valley du Kou, Burkina Faso to evaluate the efficacy of pirimiphos methyl treated DL and NWH either alone or in combination with LLINs against pyrethroid resistant Anopheles gambiae ss. Comparison was made with pyrethroid DL. Mosquitoes were genotyped for kdr and ace-1R resistant genes to investigate the insecticide resistance management potential of the combination.
  
  
  RESULTS
  The overall kdr and ace-1(R) allele frequencies were 0.95 and 0.01 respectively. Mortality with p-methyl DL and NWH alone was higher than with pyrethroid DL alone (>95% vs 40%; P<0.001). Combining pyrethroid DL with LLINs did not show improvement in mortality (48%) compared to the LLIN alone (44%) (P>0.1). Combining p-methyl DL or NWH with LLINs reduced biting rates significantly (8-9%) compared to p-methyl DL and NWH alone (>40%) and killed all An gambiae that entered the huts. Mosquitoes bearing the ace-1(R) gene were more likely to survive in huts with p-methyl DL alone (p<0.03) whereas all resistant and susceptible genotypes were killed by the combination.
  
  
  CONCLUSIONS
  P-methyl DL and NWH outperformed pyrethroid DL. Combining p-methyl DL and NWH with LLINs could provide significant epidemiological benefits against a vector population which is resistant to pyrethroids but susceptible to organophosphates. There was evidence that the single intervention would select kdr and ace-1(R) resistance genes and the combination intervention might select less strongly. Technology to bind organophosphates to plastic wall lining would be worth developing.
authors.affiliation: London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Corine
authors.initials: C
authors.lastname: Ngufor
authors.affiliation: Centre Suisse de Recherche Scientifiques, Abidjan, Cote D'Ivoire.
authors.forename: Emile
authors.initials: E
authors.lastname: Tchicaya
authors.affiliation: Centre Suisse de Recherche Scientifiques, Abidjan, Cote D'Ivoire.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Koudou
authors.affiliation: Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.
authors.forename: Sagnon
authors.initials: S
authors.lastname: N'Fale
authors.affiliation: Centre Muraz, Bobo-Dioulasso, Burkina Faso.
authors.forename: Roch
authors.initials: R
authors.lastname: Dabire
authors.affiliation: Robertson Centre for Biostatistics, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Johnson
authors.affiliation: Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
authors.forename: Hilary
authors.initials: H
authors.lastname: Ranson
authors.affiliation: London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Rowland
mesh_terms: D000483:Alleles; D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000235:genetics; D002050:Burkina Faso; D004357:Drug Synergism; D005260:Female; D017344:Genes, Insect; D005838:Genotype; D007305:Insecticide Resistance; D057148:Insecticide-Treated Bednets; D007306:Insecticides / Q000494:pharmacology*; D009032:Mosquito Control / Q000379:methods*; D010755:Organophosphates / Q000494:pharmacology*; D021261:Parasitic Sensitivity Tests; D011722:Pyrethrins / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D010755:Organophosphates; D011722:Pyrethrins