title: The geography of malaria genetics in the Democratic Republic of Congo: A complex and fragmented landscape.
abstract: Understanding how malaria parasites move between populations is important, particularly given the potential for malaria to be reintroduced into areas where it was previously eliminated. We examine the distribution of malaria genetics across seven sites within the Democratic Republic of Congo (DRC) and two nearby countries, Ghana and Kenya, in order to understand how the relatedness of malaria parasites varies across space, and whether there are barriers to the flow of malaria parasites within the DRC or across borders. Parasite DNA was retrieved from dried blood spots from 7 Demographic and Health Survey sample clusters in the DRC. Malaria genetic characteristics of parasites from Ghana and Kenya were also obtained. For each of 9 geographic sites (7 DRC, 1 Ghana and 1 Kenya), a pair-wise RST statistic was calculated, indicating the genetic distance between malaria parasites found in those locations. Mapping genetics across the spatial extent of the study area indicates a complex genetic landscape, where relatedness between two proximal sites may be relatively high (RST > 0.64) or low (RST < 0.05), and where distal sites also exhibit both high and low genetic similarity. Mantel's tests suggest that malaria genetics differ as geographic distances increase. Principal Coordinate Analysis suggests that genetically related samples are not co-located. Barrier analysis reveals no significant barriers to gene flow between locations. Malaria genetics in the DRC have a complex and fragmented landscape. Limited exchange of genes across space is reflected in greater genetic distance between malaria parasites isolated at greater geographic distances. There is, however, evidence for close genetic ties between distally located sample locations, indicating that movement of malaria parasites and flow of genes is being driven by factors other than distance decay. This research demonstrates the contributions that spatial disease ecology and landscape genetics can make to understanding the evolutionary dynamics of infectious diseases.
authors.affiliation: Department of Geographical & Sustainability Sciences, University of Iowa, Iowa City, IA, USA. Electronic address: margaret-carrel@uiowa.edu.
authors.forename: Margaret
authors.initials: M
authors.lastname: Carrel
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina- Chapel Hill Chapel Hill, NC, USA.
authors.forename: Jaymin
authors.initials: J
authors.lastname: Patel
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina- Chapel Hill Chapel Hill, NC, USA; Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA; Duke Global Health Institute, Durham, NC, USA.
authors.forename: Steve M
authors.initials: SM
authors.lastname: Taylor
authors.affiliation: Department of Geography, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Janko
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina- Chapel Hill Chapel Hill, NC, USA.
authors.forename: Melchior Kashamuka
authors.initials: MK
authors.lastname: Mwandagalirwa
authors.affiliation: Ecole de Sante Publique, Faculte de Medecine, University of Kinshasa, Kinshasa, Democratic Republic of the Congo.
authors.forename: Antoinette K
authors.initials: AK
authors.lastname: Tshefu
authors.affiliation: Center for Evolutionary Medicine & Informatics, The Biodesign Institute, Arizona State University, Tempe, AZ, USA.
authors.forename: Ananias A
authors.initials: AA
authors.lastname: Escalante
authors.affiliation: Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: McCollum
authors.affiliation: Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Md Tauqeer
authors.initials: MT
authors.lastname: Alam
authors.affiliation: Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Venkatachalam
authors.initials: V
authors.lastname: Udhayakumar
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina- Chapel Hill Chapel Hill, NC, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Meshnick
authors.affiliation: Department of Geography, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Emch
mesh_terms: D001769:Blood / Q000469:parasitology; D015023:Democratic Republic of the Congo; D051456:Gene Flow; D014644:Genetic Variation; D062306:Geography, Medical; D005869:Ghana; D006801:Humans; D007630:Kenya; D016778:Malaria, Falciparum / Q000469:parasitology / Q000635:transmission*; D018895:Microsatellite Repeats / Q000235:genetics; D010963:Plasmodium falciparum / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods
keywords: Democratic Republic of Congo; Disease ecology; Landscape genetics; Malaria