title: Microsatellite genotyping of Plasmodium vivax infections and their relapses in pregnant and non-pregnant patients on the Thai-Myanmar border.
abstract: BACKGROUND
  Plasmodium vivax infections in pregnancy are associated with low birth weight and anaemia. This parasites species is also characterised by relapses, erythrocytic infections initiated by the activation of the dormant liver stages, the hypnozoites, to mature. Genotyping of P. vivax using microsatellite markers has opened the way to comparative investigations of parasite populations. The aim of the study was to assess whether there were any differences between the parasites found in pregnant and non-pregnant patients, and/or between the admission infections and recurrent episodes during follow-up.
  
  
  METHODS
  Blood samples were collected from 18 pregnant and 18 non-pregnant patients, who had at least two recurrent episodes during follow-up, that were recruited in two previous trials on the efficacy of chloroquine treatment of P. vivax infections on the Thai-Myanmar border. DNA was purified and the P. vivax populations genotyped with respect to eight polymorphic microsatellite markers. Analyses of the genetic diversity, multiplicity of infection (MOI), and a comparison of the genotypes in the samples from each patient were conducted.
  
  
  RESULTS
  The P. vivax parasites present in the samples exhibited high genetic diversity (6 to 15 distinct allelic variants found for the 8 loci). Similar expected heterozygosity (He) values were obtained for isolates from pregnant (0.837) and non-pregnant patients (0.852). There were modest differences between the MOI values calculated for both admission and recurrence samples from the pregnant patients (2.00 and 2.05, respectively) and the equivalent samples from the non-pregnant patients (1.67 and 1.64, respectively). Furthermore, the mean number of distinct alleles enumerated in the admission samples from the pregnant (6.88) and non-pregnant (7.63) patients were significantly lower than that found in the corresponding recurrent episodes samples (9.25 and 9.63, respectively).
  
  
  CONCLUSIONS
  The P. vivax populations circulating in inhabitants along the Thai-Myanmar border, an area of low malaria transmission, displayed high genetic diversity. A subtle increase in the multiplicity of P. vivax infections in pregnant patients suggests a higher susceptibility to infection. The higher allelic diversity in the relapse as compared to the admission samples in both patient groups is consistent with the hypothesis that a febrile episode promotes the activation of hypnozoites.
authors.affiliation: Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Supinya
authors.initials: S
authors.lastname: Thanapongpichat
authors.forename: Rose
authors.initials: R
authors.lastname: McGready
authors.forename: Christine
authors.initials: C
authors.lastname: Luxemburger
authors.forename: Nicholas P J
authors.initials: NP
authors.lastname: Day
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: White
authors.forename: Francois
authors.initials: F
authors.lastname: Nosten
authors.forename: Georges
authors.initials: G
authors.lastname: Snounou
authors.forename: Mallika
authors.initials: M
authors.lastname: Imwong
mesh_terms: D000293:Adolescent; D000328:Adult; D001769:Blood / Q000469:parasitology; D002648:Child; D002675:Child, Preschool; D016172:DNA Fingerprinting / Q000379:methods*; D016054:DNA, Protozoan / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D016780:Malaria, Vivax / Q000453:epidemiology* / Q000469:parasitology; D018895:Microsatellite Repeats; D008875:Middle Aged; D017720:Molecular Epidemiology / Q000379:methods; D002052:Myanmar / Q000453:epidemiology; D010966:Plasmodium vivax / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D011110:Polymorphism, Genetic; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology* / Q000469:parasitology; D012008:Recurrence; D013785:Thailand / Q000453:epidemiology; D055815:Young Adult
chemical_list: D016054:DNA, Protozoan
references.citation: Malar J. 2011 Oct 11;10:297
references.pmid: 21989376
references.citation: Trop Med Int Health. 2007 Feb;12(2):209-18
references.pmid: 17300627
references.citation: Clin Infect Dis. 2011 Nov;53(10):977-84
references.pmid: 22002979
references.citation: J Infect Dis. 2012 Feb 15;205(4):680-3
references.pmid: 22194628
references.citation: Proc Natl Acad Sci U S A. 1993 May 15;90(10):4384-8
references.pmid: 8506277
references.citation: J Infect Dis. 2010 Aug 15;202(4):638-47
references.pmid: 20617923
references.citation: Mol Biochem Parasitol. 1993 Oct;61(2):315-20
references.pmid: 8264734
references.citation: Trans R Soc Trop Med Hyg. 1997 May-Jun;91(3):256-62
references.pmid: 9231189
references.citation: J Infect Dis. 2012 Dec 15;206(12):1904-10
references.pmid: 23053630
references.citation: Am J Trop Med Hyg. 1996;55(1 Suppl):95-100
references.pmid: 8702046
references.citation: Am J Trop Med Hyg. 2010 Feb;82(2):235-42
references.pmid: 20133999
references.citation: Trans R Soc Trop Med Hyg. 1996 Mar-Apr;90(2):105-11
references.pmid: 8761562
references.citation: Clin Microbiol Rev. 1992 Jan;5(1):26-35
references.pmid: 1735093
references.citation: Bioinformatics. 2000 Sep;16(9):847-8
references.pmid: 11108709
references.citation: Trans R Soc Trop Med Hyg. 1999 Jul-Aug;93(4):433-8
references.pmid: 10674098
references.citation: Malar J. 2012 Nov 26;11:392
references.pmid: 23181896
references.citation: Antimicrob Agents Chemother. 2000 Jun;44(6):1680-5
references.pmid: 10817728
references.citation: PLoS One. 2012;7(4):e34509
references.pmid: 22529919
references.citation: Malar J. 2011 May 05;10:113
references.pmid: 21545737
references.citation: Parasitology. 1999 Aug;119 ( Pt 2):113-25
references.pmid: 10466118
references.citation: Am J Trop Med Hyg. 2004 Apr;70(4):398-407
references.pmid: 15100454
references.citation: Lancet. 1999 Aug 14;354(9178):546-9
references.pmid: 10470698
references.citation: J Infect Dis. 2007 Apr 1;195(7):927-33
references.pmid: 17330781
references.citation: Int J Parasitol. 2007 Jul;37(8-9):1013-22
references.pmid: 17442318