title: Rapid evolution of pyrethroid resistance prevalence in Anopheles gambiae populations from the cities of Douala and Yaoundé (Cameroon).
abstract: BACKGROUND
  The adaptation of malaria vectors to urban areas is becoming a serious challenge for malaria control. The study presents the evolution of pyrethroid resistance in mosquito populations from the cities of Douala and Yaoundé between 2010 and 2013.
  
  
  METHODS
  Susceptibility tests to permethrin and deltamethrin were carried out with two- to four-day old unfed Anopheles gambiae sensu lato adults raised from larvae collected from the field. Mosquitoes resistant to permethrin and deltamethrin and control were screened to detect the presence of the kdr alleles using the TaqMan assays. Mosquitoes belonging to the An. gambiae complex were subjected to PCR assays designed for species and molecular forms identifications. The genomic region containing the upstream of intron-1 of the voltage-gated sodium channel was sequenced and compared between mosquitoes originating from different breeding habitats.
  
  
  RESULTS
  Anopheles gambiae s.l. specimens collected from the city of Douala were all Anopheles coluzzii. In Yaoundé, both An. gambiae and An. coluzzii were recorded. A rapid decrease of mosquito mortality to permethrin and deltamethrin was recorded between 2010 and 2013 in the two cities. The mortality rate varied from 80.3 to 22.3% and 94.4 to 59.7% for permethrin and deltamethrin, respectively. Both kdr alleles L1014F and L1014S were recorded. The frequency of kdr alleles increased rapidly over the study period, varying from 44 to 88.9% in Yaoundé and from 68 to 81% in Douala. The sequencing of a 1,228 bp region of intro-1 of the voltage-gated sodium channel revealed the presence of five different haplotypes. A high number of these haplotypes were recorded in An. coluzzii samples. No evidence for a recent selective sweep on intron-1 sequence within samples originating from different breeding habitat was detected using Fu's and Tajima Fs statistics.
  
  
  CONCLUSIONS
  The present study supports rapid evolution of pyrethroid resistance in vector populations from the cities of Douala and Yaoundé and calls for immediate action to fight against the increasing prevalence of pyrethroid-resistant mosquitoes.
authors.affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), PO Box 288, Yaoundé, Cameroon. antonio_nk@yahoo.fr.|Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. antonio_nk@yahoo.fr.
authors.forename: Christophe
authors.initials: C
authors.lastname: Antonio-Nkondjio
authors.affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), PO Box 288, Yaoundé, Cameroon. billytene@gmail.com.|Faculty of Sciences, University of Yaoundé I, PO Box 337, Yaoundé, Cameroon. billytene@gmail.com.
authors.forename: Billy
authors.initials: B
authors.lastname: Tene Fossog
authors.affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), PO Box 288, Yaoundé, Cameroon. edmondoev@yahoo.fr.|Faculty of Sciences, University of Yaoundé I, PO Box 337, Yaoundé, Cameroon. edmondoev@yahoo.fr.
authors.forename: Edmond
authors.initials: E
authors.lastname: Kopya
authors.affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), PO Box 288, Yaoundé, Cameroon. ypoumachu@yahoo.fr.|Malaria Research Unit of the Laboratory of Applied Biology and Ecology (MRU-LABEA), Department of Animal Biology, Faculty of Science of the University of Dschang, PO Box 067, Dschang, Cameroon. ypoumachu@yahoo.fr.
authors.forename: Yacouba
authors.initials: Y
authors.lastname: Poumachu
authors.affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), PO Box 288, Yaoundé, Cameroon. Mbenji2@yahoo.fr.|Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. Mbenji2@yahoo.fr.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Menze Djantio
authors.affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), PO Box 288, Yaoundé, Cameroon. cyrndo@yahoo.fr.|Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. cyrndo@yahoo.fr.|Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon. cyrndo@yahoo.fr.
authors.forename: Cyrille
authors.initials: C
authors.lastname: Ndo
authors.affiliation: Malaria Research Unit of the Laboratory of Applied Biology and Ecology (MRU-LABEA), Department of Animal Biology, Faculty of Science of the University of Dschang, PO Box 067, Dschang, Cameroon. timotchuinkam@yahoo.fr.
authors.forename: Timoléon
authors.initials: T
authors.lastname: Tchuinkam
authors.affiliation: Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), PO Box 288, Yaoundé, Cameroon. ambene_69@yahoo.fr.
authors.forename: Parfait
authors.initials: P
authors.lastname: Awono-Ambene
authors.affiliation: Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. Charles.Wondji@lstmed.ac.uk.
authors.forename: Charles S
authors.initials: CS
authors.lastname: Wondji
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000235:genetics*; D002163:Cameroon / Q000453:epidemiology; D019143:Evolution, Molecular; D006801:Humans; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides / Q000494:pharmacology*; D008288:Malaria / Q000453:epidemiology / Q000517:prevention & control; D011722:Pyrethrins / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D011722:Pyrethrins