title: The emergence of insecticide resistance in central Mozambique and potential threat to the successful indoor residual spraying malaria control programme.
abstract: BACKGROUND
  Malaria vector control by indoor residual spraying was reinitiated in 2006 with DDT in Zambézia province, Mozambique. In 2007, these efforts were strengthened by the President's Malaria Initiative. This manuscript reports on the monitoring and evaluation of this programme as carried out by the Malaria Decision Support Project.
  
  
  METHODS
  Mosquitoes were captured daily through a series of 114 window exit traps located at 19 sentinel sites, identified to species and analysed for sporozoites. Anopheles mosquitoes were collected resting indoors and tested for insecticide resistance following the standard WHO protocol. Annual cross sectional household parasite surveys were carried out to monitor the impact of the control programme on prevalence of Plasmodium falciparum in children aged 1 to 15 years.
  
  
  RESULTS
  A total of 3,769 and 2,853 Anopheles gambiae s.l. and Anopheles funestus, respectively, were captured from window exit traps throughout the period. In 2010 resistance to the pyrethroids lambda-cyhalothrin and permethrin and the carbamate, bendiocarb was detected in An. funestus. In 2006, the sporozoite rate in An. gambiae s.s. was 4% and this reduced to 1% over 4 rounds of spraying. The sporozoite rate for An. funestus was also reduced from 2% to 0 by 2008. Of the 437 Anopheles arabiensis identified, none were infectious. Overall prevalence of P. falciparum in the sentinel sites fell from 60% to 32% between October 2006 and October 2008.
  
  
  CONCLUSIONS
  Both An. gambiae s.s. and An. funestus were controlled effectively with the DDT-based IRS programme in Zambézia, reducing disease transmission and burden. However, the discovery of pyrethroid resistance in the province and Mozambique's policy change away from DDT to pyrethroids for IRS threatens the gains made here.
authors.affiliation: 1National Institute of Health, Av. Eduardo Mondlane/Salvador Allende, PO Box 264, Maputo, Mozambique.
authors.forename: Ana P
authors.initials: AP
authors.lastname: Abilio
authors.forename: Immo
authors.initials: I
authors.lastname: Kleinschmidt
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Rehman
authors.forename: Nelson
authors.initials: N
authors.lastname: Cuamba
authors.forename: Varsha
authors.initials: V
authors.lastname: Ramdeen
authors.forename: David S
authors.initials: DS
authors.lastname: Mthembu
authors.forename: Sarel
authors.initials: S
authors.lastname: Coetzer
authors.forename: Rajendra
authors.initials: R
authors.lastname: Maharaj
authors.forename: Craig S
authors.initials: CS
authors.lastname: Wilding
authors.forename: Andrew
authors.initials: A
authors.lastname: Steven
authors.forename: Marlize
authors.initials: M
authors.lastname: Coleman
authors.forename: Janet
authors.initials: J
authors.lastname: Hemingway
authors.forename: Michael
authors.initials: M
authors.lastname: Coleman
mesh_terms: D000293:Adolescent; D000818:Animals; D000852:Anopheles / Q000187:drug effects*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D003634:DDT / Q000494:pharmacology; D005260:Female; D006801:Humans; D007223:Infant; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D016778:Malaria, Falciparum / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control*; D008297:Male; D009032:Mosquito Control / Q000379:methods*; D009073:Mozambique; D010963:Plasmodium falciparum / Q000302:isolation & purification; D015995:Prevalence; D011722:Pyrethrins / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D011722:Pyrethrins; D003634:DDT