title: Co-occurrence and distribution of East (L1014S) and West (L1014F) African knock-down resistance in Anopheles gambiae sensu lato population of Tanzania.
abstract: OBJECTIVE
  Insecticide resistance molecular markers can provide sensitive indicators of resistance development in Anopheles vector populations. Assaying these makers is of paramount importance in the resistance monitoring programme. We investigated the presence and distribution of knock-down resistance (kdr) mutations in Anopheles gambiae s.l. in Tanzania.
  
  
  METHODS
  Indoor-resting Anopheles mosquitoes were collected from 10 sites and tested for insecticide resistance using the standard WHO protocol. Polymerase chain reaction-based molecular diagnostics were used to genotype mosquitoes and detect kdr mutations.
  
  
  RESULTS
  The An. gambiae tested were resistance to lambdacyhalothrin in Muheza, Arumeru and Muleba. Out of 350 An. gambiae s.l. genotyped, 35% were An. gambiae s.s. and 65% An. arabiensis. L1014S and L1014F mutations were detected in both An. gambiae s.s. and An. arabiensis. L1014S point mutation was found at the allelic frequency of 4-33%, while L1014F was at the allelic frequency 6-41%. The L1014S mutation was much associated with An. gambiae s.s. (χ(2) = 23.41; P < 0.0001) and L1014F associated with An. arabiensis (χ(2) = 11.21; P = 0.0008). The occurrence of the L1014S allele was significantly associated with lambdacyhalothrin resistance mosquitoes (Fisher exact P < 0.001).
  
  
  CONCLUSIONS
  The observed co-occurrence of L1014S and L1014F mutations coupled with reports of insecticide resistance in the country suggest that pyrethroid resistance is becoming a widespread phenomenon among our malaria vector populations. The presence of L1014F mutation in this East African mosquito population indicates the spreading of this gene across Africa. The potential operational implications of these findings on malaria control need further exploration.
authors.affiliation: National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania.|Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania.
authors.forename: Bilali
authors.initials: B
authors.lastname: Kabula
authors.affiliation: National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania.
authors.forename: William
authors.initials: W
authors.lastname: Kisinza
authors.affiliation: National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania.
authors.forename: Patrick
authors.initials: P
authors.lastname: Tungu
authors.affiliation: National Institute for Medical Research, Mwanza Research Centre, Mwanza, Tanzania.
authors.forename: Chacha
authors.initials: C
authors.lastname: Ndege
authors.affiliation: National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania.
authors.forename: Benard
authors.initials: B
authors.lastname: Batengana
authors.affiliation: National Institute for Medical Research, Mwanza Research Centre, Mwanza, Tanzania.
authors.forename: Douglas
authors.initials: D
authors.lastname: Kollo
authors.affiliation: National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania.
authors.forename: Robert
authors.initials: R
authors.lastname: Malima
authors.affiliation: The Presidents' Malaria Initiative, PMI/USAID Office, Dar es Salaam, Tanzania.
authors.forename: Jessica
authors.initials: J
authors.lastname: Kafuko
authors.affiliation: Global Health Division, RTI International, Dar es Salaam, Tanzania.
authors.forename: Mahdi
authors.initials: M
authors.lastname: Mohamed
authors.affiliation: National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania.|Global Health Division, RTI International, Nairobi, Kenya.
authors.forename: Stephen
authors.initials: S
authors.lastname: Magesa
mesh_terms: D000351:Africa, Eastern; D000354:Africa, Western; D019943:Amino Acid Substitution; D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000235:genetics; D005260:Female; D005787:Gene Frequency / Q000235:genetics; D005838:Genotype; D005843:Geography; D007303:Insect Vectors / Q000187:drug effects* / Q000235:genetics; D007305:Insecticide Resistance / Q000235:genetics; D007306:Insecticides / Q000494:pharmacology*; D009154:Mutation / Q000235:genetics*; D009570:Nitriles / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D011722:Pyrethrins / Q000494:pharmacology*; D013045:Species Specificity
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C037304:cyhalothrin
keywords: Anopheles gambiae; L1014F; L1014S; Tanzania; insecticide resistance; kdr