title: Rapid increase of Plasmodium falciparum dhfr/dhps resistant haplotypes, after the adoption of sulphadoxine-pyrimethamine as first line treatment in 2002, in southern Mozambique.
abstract: BACKGROUND
  In late 2002, the health authorities of Mozambique implemented sulphadoxine-pyrimethamine (SP)/amodiaquine (AQ) as first-line treatment against uncomplicated falciparum malaria. In 2004, this has been altered to SP/artesunate in line with WHO recommendations of using Artemisinin Combination Therapies (ACTs), despite the fact that all the neighbouring countries have abandoned SP-drug combinations due to high levels of SP drug resistance. In the study area, one year prior to the change to SP/AQ, SP alone was used to treat uncomplicated malaria cases. The study described here investigated the immediate impact of the change to SP on the frequency of SP and CQ resistance-related haplotypes in the Plasmodium falciparum genes Pfdhfr, Pfdhps and Pfcrt before and a year after the introduction of SP.
  
  
  METHODS
  Samples were collected during two cross sectional surveys in early 2002 and 2003 involving 796 and 692 children one year or older and adults randomly selected living in Maciana, an area located in Manhiça district, Southern Mozambique. Out of these, 171 and 173 P. falciparum positive samples were randomly selected to measure the frequency of resistance- related haplotypes in Pfdhfr, Pfdhps and Pfcrt based on results obtained by nested PCR followed by sequence-specific oligonucleotide probe (SSOP)-ELISA.
  
  
  RESULTS
  The frequency of the SP-resistance associated Pfdhps double mutant (SGEAA) haplotype increased significantly from 14% to 35% (P < 0.001), while the triple mutant Pfdhfr haplotype (CIRNI) remained high and only changed marginally from 46% to 53% (P = 0.405) after one year with SP as first-line treatment in the study area. Conversely, the combined Pfdhfr/Pfdhps quintuple mutant haplotype increased from 8% to 26% (P = 0.005). The frequency of the chloroquine resistance associated Pfcrt-CVIET haplotype was above 90% in both years.
  
  
  CONCLUSIONS
  These retrospective findings add to the general concern on the lifespan of the combination of SP/artesunate in Mozambique. The high frequency of quintuple Pfdhfr/Pfdhps haplotypes found here as early as 2002 most likely cause ideal conditions for the development of artesunate tolerance in the P. falciparum populations and may even endanger the sensitivity to the second-line drug, Coartem.
authors.affiliation: Instituto Nacional de Saúde, Ministério de Saúde, Maputo, Mozambique. Senosse@teledata.mz
authors.forename: Sonia
authors.initials: S
authors.lastname: Enosse
authors.forename: Pascal
authors.initials: P
authors.lastname: Magnussen
authors.forename: Fatima
authors.initials: F
authors.lastname: Abacassamo
authors.forename: Xavier
authors.initials: X
authors.lastname: Gómez-Olivé
authors.forename: Anita M
authors.initials: AM
authors.lastname: Rønn
authors.forename: Ricardo
authors.initials: R
authors.lastname: Thompson
authors.forename: Michael
authors.initials: M
authors.lastname: Alifrangis
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004094:Dihydropteroate Synthase / Q000235:genetics; D004338:Drug Combinations; D004351:Drug Resistance / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005787:Gene Frequency; D006239:Haplotypes; D006801:Humans; D007223:Infant; D016778:Malaria, Falciparum / Q000188:drug therapy* / Q000453:epidemiology* / Q000469:parasitology; D026901:Membrane Transport Proteins / Q000235:genetics; D009073:Mozambique / Q000453:epidemiology; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000379:methods; D015800:Protozoan Proteins / Q000235:genetics*; D011739:Pyrimethamine / Q000494:pharmacology*; D013413:Sulfadoxine / Q000494:pharmacology*; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics
chemical_list: D000962:Antimalarials; D004338:Drug Combinations; D026901:Membrane Transport Proteins; C416369:PfCRT protein, Plasmodium falciparum; D015800:Protozoan Proteins; C001205:fanasil, pyrimethamine drug combination; D013413:Sulfadoxine; D013762:Tetrahydrofolate Dehydrogenase; D004094:Dihydropteroate Synthase; D011739:Pyrimethamine