Genetic diversity of Plasmodium falciparum in human malaria cases in MaliReport as inadecuate




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Malaria Journal

, 15:353

First Online: 11 July 2016Received: 24 April 2016Accepted: 15 June 2016DOI: 10.1186-s12936-016-1397-0

Cite this article as: Nabet, C., Doumbo, S., Jeddi, F. et al. Malar J 2016 15: 353. doi:10.1186-s12936-016-1397-0

Abstract

BackgroundIn Mali, Plasmodium falciparum malaria is highly endemic and remains stable despite the implementation of various malaria control measures. Understanding P. falciparum population structure variations across the country could provide new insights to guide malaria control programmes. In this study, P. falciparum genetic diversity and population structure in regions of varying patterns of malaria transmission in Mali were analysed.

MethodsA total of 648 blood isolates adsorbed onto filter papers during population surveillance surveys December 2012–March 2013, October 2013 in four distinct sites of Mali were screened for the presence of P. falciparum via quantitative PCR qPCR. Multiple loci variable number of tandem repeats analysis MLVA using eight microsatellite markers was then performed on positive qPCR samples. Complete genotypes were then analysed for genetic diversity, genetic differentiation and linkage disequilibrium.

ResultsOf 156 qPCR-positive samples, complete genotyping of 112 samples was achieved. The parasite populations displayed high genetic diversity mean He = 0.77, which was consistent with a high level of malaria transmission in Mali. Genetic differentiation was low FST < 0.02, even between sites located approximately 900 km apart, thereby illustrating marked gene flux amongst parasite populations. The lack of linkage disequilibrium further revealed an absence of local clonal expansion, which was corroborated by the genotype relationship results. In contrast to the stable genetic diversity level observed throughout the country, mean multiplicity of infection increased from north to south from 1.4 to 2.06 and paralleled malaria transmission levels observed locally.

ConclusionsIn Mali, the high level of genetic diversity and the pronounced gene flux amongst P. falciparum populations may represent an obstacle to control malaria. Indeed, results suggest that parasite populations are polymorphic enough to adapt to their host and to counteract interventions, such as anti-malarial vaccination. Additionally, the panmictic parasite population structure imply that resistance traits may disseminate freely from one area to another, making control measures performed at a local level ineffective.

KeywordsMalaria Plasmodium falciparum Mali Genetic diversity Epidemiology MLVA AbbreviationsRDTrapid diagnostic test

MLVAmultiple loci variable number of tandem repeats analysis

SNPsingle nucleotide polymorphism

MRTCMalaria Research and Training Centre

ACTartemisinin-based combination therapy

LLINlong-lasting insecticide-treated bed net

MOImultiplicity of infection

LDlinkage disequilibrium

Cécile Nabet and Safiatou Doumbo contributed equally to this work

Electronic supplementary materialThe online version of this article doi:10.1186-s12936-016-1397-0 contains supplementary material, which is available to authorized users.

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Author: Cécile Nabet - Safiatou Doumbo - Fakhri Jeddi - Salimata Konaté - Tommaso Manciulli - Bakary Fofana - Coralie L’Ollivie

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