Variation in complexity of infection and transmission stability between neighbouring populations of Plasmodium vivax in Southern Ethiopia

S Getachew, Sheren To, Hidayat Trimarsanto, Kamala Ley-Thriemer, TG Clark, B Petros, A Aseffa, Ric Price, Sarah Auburn

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    Abstract

    Background: P. vivax is an important public health burden in Ethiopia, accounting for almost half of all malaria cases. Owing to heterogeneous transmission across the country, a stronger evidence base on local transmission dynamics is needed to optimise allocation of resources and improve malaria interventions.

    Methodology and Principal Findings: In a pilot evaluation of local level P. vivax molecular surveillance in southern Ethiopia, the diversity and population structure of isolates collected between May and November 2013 were investigated. Blood samples were collected from microscopy positive P. vivax patients recruited to clinical and cross-sectional surveys from four sites: Arbaminch, Halaba, Badawacho and Hawassa. Parasite genotyping was undertaken at nine tandem repeat markers. Eight loci were successfully genotyped in 197 samples (between 36 and 59 per site). Heterogeneity was observed in parasite diversity and structure amongst the sites. Badawacho displayed evidence of unstable transmission, with clusters of identical clonal infections. Linkage disequilibrium in Badawacho was higher (IAS = 0.32, P = 0.010) than in the other populations (IAS range = 0.01-0.02) and declined markedly after adjusting for identical infections (IAS = 0.06, P = 0.010). Other than Badawacho (HE = 0.70), population diversity was equivalently high across the sites (HE = 0.83). Polyclonal infections were more frequent in Hawassa (67%) than the other populations (range: 8-44%). Despite the variable diversity, differentiation between the sites was low (FST range: 5 x 10-3-0.03).

    Conclusions: Marked variation in parasite population structure likely reflects differing local transmission dynamics. Parasite genotyping in these heterogeneous settings has potential to provide important complementary information with which to optimise malaria control interventions.
    Original languageEnglish
    Article numbere0140780
    Pages (from-to)1-15
    Number of pages15
    JournalPLoS One
    Volume10
    DOIs
    Publication statusPublished - 2015

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    Plasmodium vivax
    Infectious Disease Transmission
    Ethiopia
    malaria
    Parasites
    parasites
    Malaria
    infection
    genotyping
    Population
    Malaria control
    population structure
    Infection
    Tandem Repeat Sequences
    tandem repeat sequences
    Public health
    resource allocation
    linkage disequilibrium
    cross-sectional studies
    Resource Allocation

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    @article{70e9e94df75a4416a7fe3bb632662597,
    title = "Variation in complexity of infection and transmission stability between neighbouring populations of Plasmodium vivax in Southern Ethiopia",
    abstract = "Background: P. vivax is an important public health burden in Ethiopia, accounting for almost half of all malaria cases. Owing to heterogeneous transmission across the country, a stronger evidence base on local transmission dynamics is needed to optimise allocation of resources and improve malaria interventions. Methodology and Principal Findings: In a pilot evaluation of local level P. vivax molecular surveillance in southern Ethiopia, the diversity and population structure of isolates collected between May and November 2013 were investigated. Blood samples were collected from microscopy positive P. vivax patients recruited to clinical and cross-sectional surveys from four sites: Arbaminch, Halaba, Badawacho and Hawassa. Parasite genotyping was undertaken at nine tandem repeat markers. Eight loci were successfully genotyped in 197 samples (between 36 and 59 per site). Heterogeneity was observed in parasite diversity and structure amongst the sites. Badawacho displayed evidence of unstable transmission, with clusters of identical clonal infections. Linkage disequilibrium in Badawacho was higher (IAS = 0.32, P = 0.010) than in the other populations (IAS range = 0.01-0.02) and declined markedly after adjusting for identical infections (IAS = 0.06, P = 0.010). Other than Badawacho (HE = 0.70), population diversity was equivalently high across the sites (HE = 0.83). Polyclonal infections were more frequent in Hawassa (67{\%}) than the other populations (range: 8-44{\%}). Despite the variable diversity, differentiation between the sites was low (FST range: 5 x 10-3-0.03). Conclusions: Marked variation in parasite population structure likely reflects differing local transmission dynamics. Parasite genotyping in these heterogeneous settings has potential to provide important complementary information with which to optimise malaria control interventions.",
    keywords = "blood, differentiation, disease transmission, Ethiopia, gene linkage disequilibrium, genetic marker, genotype, human, human tissue, major clinical study, malaria control, microscopy, parasite, Plasmodium vivax, population structure",
    author = "S Getachew and Sheren To and Hidayat Trimarsanto and Kamala Ley-Thriemer and TG Clark and B Petros and A Aseffa and Ric Price and Sarah Auburn",
    year = "2015",
    doi = "10.1371/journal.pone.0140780",
    language = "English",
    volume = "10",
    pages = "1--15",
    journal = "PLoS One",
    issn = "1932-6203",
    publisher = "Public Library of Science (PLoS)",

    }

    Variation in complexity of infection and transmission stability between neighbouring populations of Plasmodium vivax in Southern Ethiopia. / Getachew, S; To, Sheren; Trimarsanto, Hidayat; Ley-Thriemer, Kamala; Clark, TG; Petros, B; Aseffa, A; Price, Ric; Auburn, Sarah.

    In: PLoS One, Vol. 10, e0140780 , 2015, p. 1-15.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

    T1 - Variation in complexity of infection and transmission stability between neighbouring populations of Plasmodium vivax in Southern Ethiopia

    AU - Getachew, S

    AU - To, Sheren

    AU - Trimarsanto, Hidayat

    AU - Ley-Thriemer, Kamala

    AU - Clark, TG

    AU - Petros, B

    AU - Aseffa, A

    AU - Price, Ric

    AU - Auburn, Sarah

    PY - 2015

    Y1 - 2015

    N2 - Background: P. vivax is an important public health burden in Ethiopia, accounting for almost half of all malaria cases. Owing to heterogeneous transmission across the country, a stronger evidence base on local transmission dynamics is needed to optimise allocation of resources and improve malaria interventions. Methodology and Principal Findings: In a pilot evaluation of local level P. vivax molecular surveillance in southern Ethiopia, the diversity and population structure of isolates collected between May and November 2013 were investigated. Blood samples were collected from microscopy positive P. vivax patients recruited to clinical and cross-sectional surveys from four sites: Arbaminch, Halaba, Badawacho and Hawassa. Parasite genotyping was undertaken at nine tandem repeat markers. Eight loci were successfully genotyped in 197 samples (between 36 and 59 per site). Heterogeneity was observed in parasite diversity and structure amongst the sites. Badawacho displayed evidence of unstable transmission, with clusters of identical clonal infections. Linkage disequilibrium in Badawacho was higher (IAS = 0.32, P = 0.010) than in the other populations (IAS range = 0.01-0.02) and declined markedly after adjusting for identical infections (IAS = 0.06, P = 0.010). Other than Badawacho (HE = 0.70), population diversity was equivalently high across the sites (HE = 0.83). Polyclonal infections were more frequent in Hawassa (67%) than the other populations (range: 8-44%). Despite the variable diversity, differentiation between the sites was low (FST range: 5 x 10-3-0.03). Conclusions: Marked variation in parasite population structure likely reflects differing local transmission dynamics. Parasite genotyping in these heterogeneous settings has potential to provide important complementary information with which to optimise malaria control interventions.

    AB - Background: P. vivax is an important public health burden in Ethiopia, accounting for almost half of all malaria cases. Owing to heterogeneous transmission across the country, a stronger evidence base on local transmission dynamics is needed to optimise allocation of resources and improve malaria interventions. Methodology and Principal Findings: In a pilot evaluation of local level P. vivax molecular surveillance in southern Ethiopia, the diversity and population structure of isolates collected between May and November 2013 were investigated. Blood samples were collected from microscopy positive P. vivax patients recruited to clinical and cross-sectional surveys from four sites: Arbaminch, Halaba, Badawacho and Hawassa. Parasite genotyping was undertaken at nine tandem repeat markers. Eight loci were successfully genotyped in 197 samples (between 36 and 59 per site). Heterogeneity was observed in parasite diversity and structure amongst the sites. Badawacho displayed evidence of unstable transmission, with clusters of identical clonal infections. Linkage disequilibrium in Badawacho was higher (IAS = 0.32, P = 0.010) than in the other populations (IAS range = 0.01-0.02) and declined markedly after adjusting for identical infections (IAS = 0.06, P = 0.010). Other than Badawacho (HE = 0.70), population diversity was equivalently high across the sites (HE = 0.83). Polyclonal infections were more frequent in Hawassa (67%) than the other populations (range: 8-44%). Despite the variable diversity, differentiation between the sites was low (FST range: 5 x 10-3-0.03). Conclusions: Marked variation in parasite population structure likely reflects differing local transmission dynamics. Parasite genotyping in these heterogeneous settings has potential to provide important complementary information with which to optimise malaria control interventions.

    KW - blood

    KW - differentiation

    KW - disease transmission

    KW - Ethiopia

    KW - gene linkage disequilibrium

    KW - genetic marker

    KW - genotype

    KW - human

    KW - human tissue

    KW - major clinical study

    KW - malaria control

    KW - microscopy

    KW - parasite

    KW - Plasmodium vivax

    KW - population structure

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