title: Assessment of Markers of Antimalarial Drug Resistance in Plasmodium falciparum Isolates from Pregnant Women in Lagos, Nigeria.
abstract: BACKGROUND
  The use of antimalarial drugs for prevention and treatment is a major strategy in the prevention of malaria in pregnancy. Although sulphadoxine-pyrimethamine (SP) is currently recommended for intermittent preventive treatment of malaria during pregnancy in Nigeria, previously used drugs for prophylaxis such as chloroquine (CQ) and pyrimethamine are accessible as they are purchased over the counter. This study describes the markers of absence or presence of resistance to quinoline (Pfcrt and Pfmdr 1) and type 1 antifolate antimalarial medicines (Pfdhfr).
  
  
  METHODS
  Plasmodium falciparum-positive dried blood spots from pregnant women attending antenatal clinics for the first time during current pregnancy were investigated for the presence of mutations at codons 72-76 of Plasmodium falciparum chloroquine resistance transporter (Pfcrt) gene by real time polymerase chain reaction (PCR) using haplotype-specific probes. PCR followed by sequence analysis was used to identify mutations at codons 86, 184, 1034, 1042 and 1246 of P. falciparum multi-drug resistance-1 (Pfmdr1) gene; and codons 16, 50, 51, 59, 108, 140 and 164 of Pfdhfr gene.
  
  
  RESULTS
  Two haplotypes of Pfcrt (n = 54) were observed: CVMNK 13(24.2%) and CVIET 41 (75.9%) of the samples. The SVMNT haplotype was absent in this population. The Pfmdr1 (n = 28) haplotypes were NYSND 15(53.6%), YYSND 5(17.9%), NFSND 6(21.4%) and YFSND 2(7.1%). The Pfdhfr (n = 15) were ACNCSVI 4(26.7%), and ACICNSVI 1(6.7%) and ACIRNVI 10 (66.7%). The rate of occurrence of Pfcrt 76T, Pfdhfr108N, Pfmdr186Y and 184F were 75.9%, 73.3%, 25% and 28.1% respectively. The Pfmdr1 86Y was associated with low parasitaemia (median = 71 parasites/μl, P = 0.024) while Pfcrt 76T was associated with young maternal age (mean 24.1 ± 4.5 years; P = 0.006). The median parasitaemia were similar (P>0.05) in wild and mutant strains of Pfcrt 76, Pfmdr1 184 and Pfdhfr 108. There was no association between gravidity or gestational age of the women and presence of mutations in the Pfcrt, Pfmdr1 or Pfdhfr genes (P>0.05).
  
  
  CONCLUSIONS
  Markers of resistance to chloroquine and pyrimethamine were high, whereas cycloguanil-resistance marker was not present in the studied population. The low level of mutations in the Pfmdr1gene indicates likely efficacy of amodiaquine against malaria in pregnancy.
authors.affiliation: Malaria Research Laboratory, Nigerian Institute of Medical Research, Lagos, Nigeria.
authors.forename: Chimere Obiora
authors.initials: CO
authors.lastname: Agomo
authors.affiliation: ANDI Centre of Excellence for Malaria Diagnosis/WHO/TDR/FIND Malaria Specimen Bank Site, College of Medicine, University of Lagos, Idi-Araba, Lagos, Nigeria.
authors.forename: Wellington Aghoghovwia
authors.initials: WA
authors.lastname: Oyibo
authors.affiliation: Department of Immunology, London School of Tropical Medicine and Hygiene, London, United Kingdom.
authors.forename: Colin
authors.initials: C
authors.lastname: Sutherland
authors.affiliation: Department of Immunology, London School of Tropical Medicine and Hygiene, London, United Kingdom.
authors.forename: Rachael
authors.initials: R
authors.lastname: Hallet
authors.affiliation: Department of Immunology, London School of Tropical Medicine and Hygiene, London, United Kingdom.
authors.forename: Mary
authors.initials: M
authors.lastname: Oguike
mesh_terms: D000328:Adult; D000962:Antimalarials / Q000627:therapeutic use*; D004351:Drug Resistance / Q000235:genetics*; D005260:Female; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy*; D026901:Membrane Transport Proteins / Q000235:genetics*; D009549:Nigeria; D010963:Plasmodium falciparum / Q000302:isolation & purification*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000188:drug therapy*; D037841:Pregnant People; D015800:Protozoan Proteins / Q000235:genetics*; D011804:Quinolines / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D000962:Antimalarials; D026901:Membrane Transport Proteins; C416369:PfCRT protein, Plasmodium falciparum; D015800:Protozoan Proteins; D011804:Quinolines; C037219:quinoline