Distribution of Giardia duodenalis Assemblages A and B among Children Living in a Remote Indigenous Community of the Northern Territory, Australia

Amy Asher, Deborah Holt, Ross Andrews, Michelle Power

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    Abstract

    Giardiasis is a communicable gastrointestinal disease caused by Giardia duodenalis and two genetic assemblages, A and B, cause human infection. In remote Indigenous communities of Australia, giardiasis is highly prevalent among children but disease transmission is poorly understood. This study investigated the prevalence of Giardia and genetic subtypes contributing to human disease in a remote Indigenous community, in the Northern Territory of Australia. Eighty-seven faecal samples were collected from 74 children (<15 years) over an 18 month period, and the distribution of positive cases relative to participant age and gender were examined. Screening by microscopy and 18S rRNA PCR amplification showed 66.7% (58/87) of faecal samples were positive for Giardia. Both males and females were equally affected and high detection rates were obtained for participants aged 0-<5 years and 5-<10 years (66.0 and 60.0% respectively). For 58.6% of the positive samples, Giardia was only detected by 18S rRNA PCR. Approximately 75% of cases were assemblage B, and subassemblage analyses using terminal restriction fragment length polymorphism of the glutamate dehydrogenase gene demonstrated that a variety of genetic variants were present. The high proportion of positive cases that were not detectable by microscopy, and dominance of assemblage B cases highlights the need for further research in this community, to assess the contribution of Giardia to chronic gastrointestinal disease among children, and to understand conditions conductive to assemblage B transmission. 
    Original languageEnglish
    Pages (from-to)1-7
    Number of pages7
    JournalPLoS One
    Volume9
    Issue number11
    DOIs
    Publication statusPublished - 20 Nov 2014

    Fingerprint

    Northern Territory
    Giardia
    Giardia lamblia
    giardiasis
    Giardiasis
    Gastrointestinal Diseases
    digestive system diseases
    Microscopy
    microscopy
    Microscopic examination
    ribosomal RNA
    Polymerase Chain Reaction
    Glutamate Dehydrogenase
    glutamate dehydrogenase
    disease transmission
    Polymorphism
    human diseases
    sampling
    Restriction Fragment Length Polymorphisms
    dominance (genetics)

    Cite this

    @article{b99ba68cc82d445cbd2b55f87d59dba4,
    title = "Distribution of Giardia duodenalis Assemblages A and B among Children Living in a Remote Indigenous Community of the Northern Territory, Australia",
    abstract = "Giardiasis is a communicable gastrointestinal disease caused by Giardia duodenalis and two genetic assemblages, A and B, cause human infection. In remote Indigenous communities of Australia, giardiasis is highly prevalent among children but disease transmission is poorly understood. This study investigated the prevalence of Giardia and genetic subtypes contributing to human disease in a remote Indigenous community, in the Northern Territory of Australia. Eighty-seven faecal samples were collected from 74 children (<15 years) over an 18 month period, and the distribution of positive cases relative to participant age and gender were examined. Screening by microscopy and 18S rRNA PCR amplification showed 66.7{\%} (58/87) of faecal samples were positive for Giardia. Both males and females were equally affected and high detection rates were obtained for participants aged 0-<5 years and 5-<10 years (66.0 and 60.0{\%} respectively). For 58.6{\%} of the positive samples, Giardia was only detected by 18S rRNA PCR. Approximately 75{\%} of cases were assemblage B, and subassemblage analyses using terminal restriction fragment length polymorphism of the glutamate dehydrogenase gene demonstrated that a variety of genetic variants were present. The high proportion of positive cases that were not detectable by microscopy, and dominance of assemblage B cases highlights the need for further research in this community, to assess the contribution of Giardia to chronic gastrointestinal disease among children, and to understand conditions conductive to assemblage B transmission. ",
    keywords = "glutamate dehydrogenase, RNA 18S, protozoal DNA, accuracy, adolescent, age distribution, Article, Australia, child, community dynamics, comparative study, controlled study, DNA sequence, feces analysis, female, gene amplification, gene locus, genetic assemblage A, genetic assemblage B, genetic screening, genetic variability, genotype, Giardia lamblia, giardiasis, glutamate dehydrogenase gene, human, indigenous people, infant, major clinical study, male, microscopy, molecular genetics, nonhuman, parasite identification, parasite load, parasite prevalence, parasite transmission, polymerase chain reaction, preschool child, restriction fragment length polymorphism, RNA gene, school child, terminal restriction fragment length polymorphism, classification, ethnology, feces, genetics, Giardia intestinalis, isolation and purification, parasitology, Adolescent, Child, Child, Preschool, DNA, Protozoan, Feces, Female, Genetic Variation, Giardiasis, Humans, Infant, Male, RNA, Ribosomal, 18S",
    author = "Amy Asher and Deborah Holt and Ross Andrews and Michelle Power",
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    doi = "10.1371/journal.pone.0112058",
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    Distribution of Giardia duodenalis Assemblages A and B among Children Living in a Remote Indigenous Community of the Northern Territory, Australia. / Asher, Amy; Holt, Deborah; Andrews, Ross; Power, Michelle.

    In: PLoS One, Vol. 9, No. 11, 20.11.2014, p. 1-7.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

    T1 - Distribution of Giardia duodenalis Assemblages A and B among Children Living in a Remote Indigenous Community of the Northern Territory, Australia

    AU - Asher, Amy

    AU - Holt, Deborah

    AU - Andrews, Ross

    AU - Power, Michelle

    N1 - NHMRC Grant No.: 605804

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    N2 - Giardiasis is a communicable gastrointestinal disease caused by Giardia duodenalis and two genetic assemblages, A and B, cause human infection. In remote Indigenous communities of Australia, giardiasis is highly prevalent among children but disease transmission is poorly understood. This study investigated the prevalence of Giardia and genetic subtypes contributing to human disease in a remote Indigenous community, in the Northern Territory of Australia. Eighty-seven faecal samples were collected from 74 children (<15 years) over an 18 month period, and the distribution of positive cases relative to participant age and gender were examined. Screening by microscopy and 18S rRNA PCR amplification showed 66.7% (58/87) of faecal samples were positive for Giardia. Both males and females were equally affected and high detection rates were obtained for participants aged 0-<5 years and 5-<10 years (66.0 and 60.0% respectively). For 58.6% of the positive samples, Giardia was only detected by 18S rRNA PCR. Approximately 75% of cases were assemblage B, and subassemblage analyses using terminal restriction fragment length polymorphism of the glutamate dehydrogenase gene demonstrated that a variety of genetic variants were present. The high proportion of positive cases that were not detectable by microscopy, and dominance of assemblage B cases highlights the need for further research in this community, to assess the contribution of Giardia to chronic gastrointestinal disease among children, and to understand conditions conductive to assemblage B transmission. 

    AB - Giardiasis is a communicable gastrointestinal disease caused by Giardia duodenalis and two genetic assemblages, A and B, cause human infection. In remote Indigenous communities of Australia, giardiasis is highly prevalent among children but disease transmission is poorly understood. This study investigated the prevalence of Giardia and genetic subtypes contributing to human disease in a remote Indigenous community, in the Northern Territory of Australia. Eighty-seven faecal samples were collected from 74 children (<15 years) over an 18 month period, and the distribution of positive cases relative to participant age and gender were examined. Screening by microscopy and 18S rRNA PCR amplification showed 66.7% (58/87) of faecal samples were positive for Giardia. Both males and females were equally affected and high detection rates were obtained for participants aged 0-<5 years and 5-<10 years (66.0 and 60.0% respectively). For 58.6% of the positive samples, Giardia was only detected by 18S rRNA PCR. Approximately 75% of cases were assemblage B, and subassemblage analyses using terminal restriction fragment length polymorphism of the glutamate dehydrogenase gene demonstrated that a variety of genetic variants were present. The high proportion of positive cases that were not detectable by microscopy, and dominance of assemblage B cases highlights the need for further research in this community, to assess the contribution of Giardia to chronic gastrointestinal disease among children, and to understand conditions conductive to assemblage B transmission. 

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