Publication: Microsatellite genotyping of Plasmodium vivax infections and their relapses in pregnant and non-pregnant patients on the Thai-Myanmar border
Issued Date
2013
Resource Type
Language
eng
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Mahidol University
Rights Holder(s)
BioMed Central
Bibliographic Citation
Malaria Journal. Vol.12, (2013), 275
Suggested Citation
Supinya Thanapongpichat, McGready, Rose, Luxemburger, Christine, Day, Nicholas PJ., White, Nicholas J., Nosten, Francois, Snounou, Georges, Mallika Imwong Microsatellite genotyping of Plasmodium vivax infections and their relapses in pregnant and non-pregnant patients on the Thai-Myanmar border. Malaria Journal. Vol.12, (2013), 275. Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/2807
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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.