title: Molecular monitoring of Plasmodium falciparum super-resistance to sulfadoxine-pyrimethamine in Tanzania.
abstract: Sulfadoxine-pyrimethamine (SP) is recommended for prophylactic treatment of malaria in pregnancy while artemisinin combination therapy is the recommended first-line anti-malarial treatment. Selection of SP resistance is ongoing since SP is readily available in health facilities and in private drug shops in sub-Saharan Africa. This study reports on the prevalence and distribution of Pfdhps mutations A540E and A581G in Tanzania. When found together, these mutations confer high-level SP resistance (sometimes referred to as 'super-resistance'), which is associated with loss in protective efficacy of SP-IPTp.
  
  
  
  DNA samples were extracted from malaria-positive blood samples on filter paper, used malaria rapid diagnostic test strips and whole blood collected from eight sites in seven administrative regions of Tanzania. PCR-RFLP and SSOP-ELISA techniques were used to genotype the A540E and A581G Pfdhps. Data were analysed using SPSS version 18 while Chi square and/or Fischer Exact tests were used to compare prevalence between regions.
  
  
  
  A high inter-regional variation of Pfdhps-540E was observed (χ(2) = 76.8, p < 0.001). High inter-regional variation of 581G was observed (FE = 85.3, p < 0.001). Both Tanga and Kagera were found to have the highest levels of SP resistance. A high prevalence of Pfdhps-581G was observed in Tanga (56.6 %) in northeastern Tanzania and in Kagera (20.4 %) in northwestern Tanzania and the 540-581 EG haplotype was found at 54.5 and 19.4 %, respectively. Pfdhps-581G was not detected in Pwani and Lindi regions located south of Tanga region.
  
  
  
  Selection of SP super-resistant Pfdhps A581G is highest in northern Tanzania. Variation in distribution of SP resistance is observed across the country: northeastern Tanga region and northwestern Kagera region have highest prevalence of SP super-resistance markers, while in Pwani and Lindi in the southeast the prevalence of super-resistance was zero. More studies should be conducted to understand the factors underlying the remarkable heterogeneity in SP resistance in the country.
authors.affiliation: Kilimanjaro Christian Medical University College, Moshi, Tanzania. rekavishe@yahoo.com.
authors.forename: Reginald A
authors.initials: RA
authors.lastname: Kavishe
authors.affiliation: Kilimanjaro Christian Medical University College, Moshi, Tanzania.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Kaaya
authors.affiliation: Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Sidsel
authors.initials: S
authors.lastname: Nag
authors.affiliation: Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Camilla
authors.initials: C
authors.lastname: Krogsgaard
authors.affiliation: Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jakob Ginsbak
authors.initials: JG
authors.lastname: Notland
authors.affiliation: Kilimanjaro Christian Medical University College, Moshi, Tanzania.
authors.forename: Adellaida A
authors.initials: AA
authors.lastname: Kavishe
authors.affiliation: National Institute for Medical Research, Tanga Centre, Tanzania.
authors.forename: Deus
authors.initials: D
authors.lastname: Ishengoma
authors.affiliation: London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Cally
authors.initials: C
authors.lastname: Roper
authors.affiliation: Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Michael
authors.initials: M
authors.lastname: Alifrangis
mesh_terms: D000962:Antimalarials / Q000494:pharmacology*; D016054:DNA, Protozoan / Q000235:genetics / Q000302:isolation & purification; D004094:Dihydropteroate Synthase / Q000235:genetics*; D004338:Drug Combinations; D004351:Drug Resistance; D005787:Gene Frequency; D060005:Genotyping Techniques; D006801:Humans; D016778:Malaria, Falciparum / Q000469:parasitology; D020125:Mutation, Missense; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D011739:Pyrimethamine / Q000494:pharmacology*; D013413:Sulfadoxine / Q000494:pharmacology*; D013636:Tanzania
chemical_list: D000962:Antimalarials; D016054:DNA, Protozoan; D004338:Drug Combinations; C001205:fanasil, pyrimethamine drug combination; D013413:Sulfadoxine; D004094:Dihydropteroate Synthase; D011739:Pyrimethamine
keywords: Anti-malarial drugs; Drug resistance; Malaria; Mutations; Parasites; Plasmodium falciparum; Polymorphisms; SP-resistance; SP-super resistance; Sulfadoxine-pyrimethamine; Tanzania