Hopping Over Red Leg: The Metamorphosis of Amphibian Pathology

Pessier, Allan P.

doi:10.1177/0300985817699861

Cited by 6 publications

(5 citation statements)

References 21 publications

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“…For the especially vulnerable vertebrate class Amphibia, the Global Amphibian Assessment first reported 32.5% of species as threatened with extinction (14) and that estimate has since risen to 40% of species (5,6), with an increase in concern for disease impacts (2,(15)(16)(17)(18)(19)(20). Amphibian diseases span both lethal and sublethal multiple-host species infections by microparasites such as trematodes (21), bacteria (22), fungi (15,23,24), protists (25,26), and viruses (16,24). Information on amphibian disease-causing pathogens has increased substantially in the last two decades, especially relative to field surveillance of taxonomic and geographic patterns of pathogen occurrences at global scales (27)(28)(29)(30)(31) and experimental research that illustrates species-specific vulnerabilities and interacting factors (24,32).…”

Section: Introductionmentioning

confidence: 99%

Global Patterns of the Fungal Pathogen Batrachochytrium dendrobatidis Support Conservation Urgency

et al. 2021

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The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) is a skin pathogen that can cause the emerging infectious disease chytridiomycosis in susceptible species. It has been considered one of the most severe threats to amphibian biodiversity. We aimed to provide an updated compilation of global Bd occurrences by host taxon and geography, and with the larger global Bd dataset we reanalyzed Bd associations with environmental metrics at the world and regional scales. We also compared our Bd data compilation with a recent independent assessment to provide a more comprehensive count of species and countries with Bd occurrences. Bd has been detected in 1,375 of 2,525 (55%) species sampled, more than doubling known species infections since 2013. Bd occurrence is known from 93 of 134 (69%) countries at this writing; this compares to known occurrences in 56 of 82 (68%) countries in 2013. Climate-niche space is highly associated with Bd detection, with different climate metrics emerging as key predictors of Bd occurrence at regional scales; this warrants further assessment relative to climate-change projections. The accretion of Bd occurrence reports points to the common aims of worldwide investigators to understand the conservation concerns for amphibian biodiversity in the face of potential disease threat. Renewed calls for better mitigation of amphibian disease threats resonate across continents with amphibians, especially outside Asia. As Bd appears to be able to infect about half of amphibian taxa and sites, there is considerable room for biosecurity actions to forestall its spread using both bottom-up community-run efforts and top-down national-to-international policies. Conservation safeguards for sensitive species and biodiversity refugia are continuing priorities.

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Section: Introductionmentioning

confidence: 99%

Global Patterns of the Fungal Pathogen Batrachochytrium dendrobatidis Support Conservation Urgency

et al. 2021

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“…Freshwater Ecosystems, 28( 2 ). Indeed, proving disease-induced declines is a challenging task and simply surveying for a pathogen or disease in a declining population is not sufficient to infer causality (Pessier, 2017). The gold standard for demonstrating disease-related declines involves collecting population data prior to emergence, estimating disease prevalence, observing disease signs and population effects or mortality, isolating the pathogen and fulfilling Koch's postulates e.g.…”

Section: Aquatic Conservation: Marine and 2829mentioning

confidence: 99%

“…2017;Pessier, 2017). The fact that severe Perkinsea infections were only recently discovered as a source of amphibian mortality in the US is a lesson to retain disciplined vigilance when examining new detecting genetic material of pathogens, but quantitative PCR (qPCR) based methods don't come without important caveats.…”

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Draft for Open Consultation. The Amphibian Conservation Action Plan (ACAP): A status review and roadmap for global amphibian conservation.

SSC¹

2022

Preprint

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As the most threatened vertebrate class on earth, amphibians are at the forefront of the biodiversity crisis, with the start of global amphibian declines and extinctions dating back several decades now. The Amphibian Conservation Action Plan (ACAP), the first taxonomic class-level plan of its kind, was first published in 2007 and then updated as a digital resource in 2015, with the goal of acting as a unified global strategy to save amphibians. However, although there have been resources allocated to amphibian conservation since the first ACAP, these have not been of the order of magnitude needed to adequately address the global amphibian crisis.In an effort to help improve this situation the current ACAP is adopting a different strategy: the development of two complementary documents that work to 1) synthesise developments in major themes of amphibian conservation over the last 15 years (an academic status review – this document), and 2) summarise the key take-home messages and recommendations to a broader audience in a user-friendly way (a practitioner document that will follow the status review). The purpose is thus to provide the most up-to-date evidence on threats and approaches to amphibian conservation, and from there identify gaps and priorities that can then be disseminated and adopted by stakeholders across the globe.Each chapter of this status review was developed by the matching Amphibian Specialist Group’s (ASG) thematic working groups. Led by 1-3 working group chairs and supported by working group members, chapters have also had the input of professionals outside of ASG with expertise in given themes. This document consists of two introductory chapters and twelve thematic chapters divided into three sections: •Threats - Chapters 3-7 on climate change; ecotoxicology; habitat loss; infectious diseases; and trade and sustainable use•Informing decision-making - Chapters 8-10 on communications and education; conservation planning; and surveys and monitoring•Species management - Chapters 11-14 on conservation breeding; assisted reproductive technologies and biobanking; genomics; and translocationsIn broad terms, each chapter covers the most important knowledge, technological and conceptual developments in a particular theme over the last decade and a half, highlighting knowledge gaps, challenges, needs and opportunities for future conservation action.Key messages1.As a whole there is an enormous deficit in information for most amphibian species, which hampers decision-making and evidence-based, conservation action. Increased collaborations both within and outside the amphibian conservation community are urgently needed to begin to bridge some of these information gaps. Integrating different approaches can help augment information and leverage additional support to amphibian conservation.2.While this document is global in scope it is informed by local and regional realities. Not everything that is in this document will be transferable to every region. However, those aspects that are relevant to a region can be addressed accordingly, and these results can then feedback again into a global strategy, and be readapted in other regions to benefit from the shared experience. Translation from local to global and back to local is crucial to ensure that regional experiences feed into a global framework and that this framework accurately reflects shared patterns and realities so that it can inform international conventions and organisations, especially in view of global environmental change.3.Relative to the scope of amphibian declines and extinctions, adequate financial and human resources and necessary policy measures have largely lagged behind this decades-long crisis. Should this pattern persist, we can expect to continue losing amphibian populations and species in increasingly large numbers. It is therefore critical that amphibian conservation becomes both an integral and a conspicuous part of the biodiversity conservation agenda of international and national conservation organisations of all sizes, of national and subnational levels of government, of the various institutions that focus on biodiversity education and research, of funding entities, and of organised communities and media.

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“…8 Yet, incomplete postmortem investigations may lead to misdiagnosis given the epidemiological and pathological similarities of some amphibian diseases and the existence of subclinical carriers. 10,16,20,28 Establishing a case definition is one route to standardize diagnostic results, promote consistent reporting of emerging diseases, and aid in differentiating diseases with overlapping diagnostic criteria. Although standard in human medicine, case definitions are uncommon for wildlife diseases.…”

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confidence: 99%

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confidence: 99%

Pathology and Case Definition of Severe Perkinsea Infection of Frogs

2018

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Severe Perkinsea infection (SPI) is an emerging disease of frogs responsible for mass mortalities of tadpoles across the United States. It is caused by protozoa belonging to the phylum Perkinsozoa that form a distinct group referred to as the Pathogenic Perkinsea Clade of frogs. In this work, we provide detailed description of gross and histologic lesions from 178 naturally infected tadpoles, including 10 species from 22 mortality events and 6 amphibian health monitoring studies from diverse geographic areas. On external examination, we observed abdominal distension (10, 5.6%), cutaneous erythema and petechia (3, 1.7%), subcutaneous edema (3, 1.7%), and areas of white skin discoloration (3, 1.7%). On macroscopic examination of internal organs, we found hepatomegaly (68, 38.2%), splenomegaly (51, 28.7%), nephromegaly (47, 26.4%), ascites (15, 8.4%), segmental irregular thickening and white discoloration of the intestine (8, 4.5%), pancreatomegaly (4, 2.2%), and pancreatic petechia (1, 0.6%). Histologically, over 60% of the liver (148/165, 89.7%), kidney (113/147, 76.9%), spleen (96/97, 99%), and pancreas (46/68, 67.6%) were invaded by myriad intracellular and extracellular Perkinsea hypnospore-like and trophozoite-like organisms. Numerous other tissues were affected to a lesser extent. Mild histiocytic inflammation with fewer lymphocytes or eosinophils was commonly observed in areas of infection that were not obscured by lympho-granulocytic hematopoietic tissue. In light of these observations, we suggest a logical pathogenesis sequence. Finally, we propose a "case definition" for SPI to promote standardized communication of results and prevent misdiagnosis with epidemiological and pathologically overlapping diseases such as ranavirosis.

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Hopping Over Red Leg: The Metamorphosis of Amphibian Pathology

Cited by 6 publications

References 21 publications

Global Patterns of the Fungal Pathogen Batrachochytrium dendrobatidis Support Conservation Urgency

Global Patterns of the Fungal Pathogen Batrachochytrium dendrobatidis Support Conservation Urgency

Draft for Open Consultation. The Amphibian Conservation Action Plan (ACAP): A status review and roadmap for global amphibian conservation.

Pathology and Case Definition of Severe Perkinsea Infection of Frogs

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