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Persistence, impacts and environmental drivers of covert infections in invertebrate hosts

BACKGROUND: Persistent covert infections of the myxozoan, Tetracapsuloides bryosalmonae, in primary invertebrate hosts (the freshwater bryozoan, Fredericella sultana) have been proposed to represent a reservoir for proliferative kidney disease in secondary fish hosts. However, we have limited unders...

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Autores principales: Fontes, Inês, Hartikainen, Hanna, Williams, Chris, Okamura, Beth
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5668978/
https://www.ncbi.nlm.nih.gov/pubmed/29096700
http://dx.doi.org/10.1186/s13071-017-2495-8
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author Fontes, Inês
Hartikainen, Hanna
Williams, Chris
Okamura, Beth
author_facet Fontes, Inês
Hartikainen, Hanna
Williams, Chris
Okamura, Beth
author_sort Fontes, Inês
collection PubMed
description BACKGROUND: Persistent covert infections of the myxozoan, Tetracapsuloides bryosalmonae, in primary invertebrate hosts (the freshwater bryozoan, Fredericella sultana) have been proposed to represent a reservoir for proliferative kidney disease in secondary fish hosts. However, we have limited understanding of how covert infections persist and vary in bryozoan populations over time and space and how they may impact these populations. In addition, previous studies have likely underestimated covert infection prevalence. To improve our understanding of the dynamics, impacts and implications of covert infections we employed a highly sensitive polymerase chain reaction (PCR) assay and undertook the first investigation of covert infections in the field over an annual period by sampling bryozoans every 45 days from three populations within each of three rivers. RESULTS: Covert infections persisted throughout the year and prevalence varied within and between rivers, but were often > 50%. Variation in temperature and water chemistry were linked with changes in prevalence in a manner consistent with the maintenance of covert infections during periods of low productivity and thus poor growth conditions for both bryozoans and T. bryosalmonae. The presence and increased severity of covert infections reduced host growth but only when bryozoans were also investing in the production of overwintering propagules (statoblasts). However, because statoblast production is transitory, this effect is unlikely to greatly impact the capacity of bryozoan populations to act as persistent sources of infections and hence potential disease outbreaks in farmed and wild fish populations. CONCLUSIONS: We demonstrate that covert infections are widespread and persist over space and time in bryozoan populations. To our knowledge, this is the first long-term study of covert infections in a field setting. Review of the results of this and previous studies enables us to identify key questions related to the ecology and evolution of covert infection strategies and associated host-parasite interactions. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13071-017-2495-8) contains supplementary material, which is available to authorized users.
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spelling pubmed-56689782017-11-08 Persistence, impacts and environmental drivers of covert infections in invertebrate hosts Fontes, Inês Hartikainen, Hanna Williams, Chris Okamura, Beth Parasit Vectors Research BACKGROUND: Persistent covert infections of the myxozoan, Tetracapsuloides bryosalmonae, in primary invertebrate hosts (the freshwater bryozoan, Fredericella sultana) have been proposed to represent a reservoir for proliferative kidney disease in secondary fish hosts. However, we have limited understanding of how covert infections persist and vary in bryozoan populations over time and space and how they may impact these populations. In addition, previous studies have likely underestimated covert infection prevalence. To improve our understanding of the dynamics, impacts and implications of covert infections we employed a highly sensitive polymerase chain reaction (PCR) assay and undertook the first investigation of covert infections in the field over an annual period by sampling bryozoans every 45 days from three populations within each of three rivers. RESULTS: Covert infections persisted throughout the year and prevalence varied within and between rivers, but were often > 50%. Variation in temperature and water chemistry were linked with changes in prevalence in a manner consistent with the maintenance of covert infections during periods of low productivity and thus poor growth conditions for both bryozoans and T. bryosalmonae. The presence and increased severity of covert infections reduced host growth but only when bryozoans were also investing in the production of overwintering propagules (statoblasts). However, because statoblast production is transitory, this effect is unlikely to greatly impact the capacity of bryozoan populations to act as persistent sources of infections and hence potential disease outbreaks in farmed and wild fish populations. CONCLUSIONS: We demonstrate that covert infections are widespread and persist over space and time in bryozoan populations. To our knowledge, this is the first long-term study of covert infections in a field setting. Review of the results of this and previous studies enables us to identify key questions related to the ecology and evolution of covert infection strategies and associated host-parasite interactions. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13071-017-2495-8) contains supplementary material, which is available to authorized users. BioMed Central 2017-11-02 /pmc/articles/PMC5668978/ /pubmed/29096700 http://dx.doi.org/10.1186/s13071-017-2495-8 Text en © The Author(s). 2017 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Fontes, Inês
Hartikainen, Hanna
Williams, Chris
Okamura, Beth
Persistence, impacts and environmental drivers of covert infections in invertebrate hosts
title Persistence, impacts and environmental drivers of covert infections in invertebrate hosts
title_full Persistence, impacts and environmental drivers of covert infections in invertebrate hosts
title_fullStr Persistence, impacts and environmental drivers of covert infections in invertebrate hosts
title_full_unstemmed Persistence, impacts and environmental drivers of covert infections in invertebrate hosts
title_short Persistence, impacts and environmental drivers of covert infections in invertebrate hosts
title_sort persistence, impacts and environmental drivers of covert infections in invertebrate hosts
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5668978/
https://www.ncbi.nlm.nih.gov/pubmed/29096700
http://dx.doi.org/10.1186/s13071-017-2495-8
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