title: Anopheles gambiae distribution and insecticide resistance in the cities of Douala and Yaoundé (Cameroon): influence of urban agriculture and pollution.
abstract: BACKGROUND
  Urban malaria is becoming a major health priority across Africa. A study was undertaken to assess the importance of urban pollution and agriculture practice on the distribution and susceptibility to insecticide of malaria vectors in the two main cities in Cameroon.
  
  
  METHODS
  Anopheline larval breeding sites were surveyed and water samples analysed monthly from October 2009 to December 2010. Parameters analysed included turbidity, pH, temperature, conductivity, sulfates, phosphates, nitrates, nitrites, ammonia, aluminium, alkalinity, iron, potassium, manganese, magnesium, magnesium hardness and total hardness. Characteristics of water bodies in urban areas were compared to rural areas and between urban sites. The level of susceptibility of Anopheles gambiae to 4% DDT, 0.75% permethrin, 0.05% deltamethrin, 0.1% bendiocarb and 5% malathion were compared between mosquitoes collected from polluted, non polluted and cultivated areas.
  
  
  RESULTS
  A total of 1,546 breeding sites, 690 in Yaoundé and 856 in Douala, were sampled in the course of the study. Almost all measured parameters had a concentration of 2- to 100-fold higher in urban compare to rural breeding sites. No resistance to malathion was detected, but bendiocarb resistance was present in Yaounde. Very low mortality rates were observed following DDT or permethrin exposure, associated with high kdr frequencies. Mosquitoes collected in cultivated areas, exhibited the highest resistant levels. There was little difference in insecticide resistance or kdr allele frequency in mosquitoes collected from polluted versus non-polluted sites.
  
  
  CONCLUSIONS
  The data confirm high selection pressure on mosquitoes originating from urban areas and suggest urban agriculture rather than pollution as the major factor driving resistance to insecticide.
authors.affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon. antonio_nk@yahoo.fr
authors.forename: Christophe
authors.initials: C
authors.lastname: Antonio-Nkondjio
authors.forename: Billy Tene
authors.initials: BT
authors.lastname: Fossog
authors.forename: Cyrille
authors.initials: C
authors.lastname: Ndo
authors.forename: Benjamin Menze
authors.initials: BM
authors.lastname: Djantio
authors.forename: Serge Zebaze
authors.initials: SZ
authors.lastname: Togouet
authors.forename: Parfait
authors.initials: P
authors.lastname: Awono-Ambene
authors.forename: Carlo
authors.initials: C
authors.lastname: Costantini
authors.forename: Charles S
authors.initials: CS
authors.lastname: Wondji
authors.forename: Hilary
authors.initials: H
authors.lastname: Ranson
mesh_terms: D000383:Agriculture / Q000379:methods*; D000818:Animals; D000852:Anopheles / Q000187:drug effects / Q000254:growth & development*; D002163:Cameroon; D004787:Environmental Pollution; D006801:Humans; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology; D012641:Selection, Genetic; D014505:Urban Population; D014867:Water / Q000737:chemistry / Q000469:parasitology
chemical_list: D007306:Insecticides; D014867:Water