Selected Emerging Infectious Diseases of Amphibians

Latney, La’Toya V.; Klaphake, Eric

doi:10.1016/j.cvex.2020.01.003

Cited by 10 publications

(5 citation statements)

References 84 publications

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“…Disease-causing bacteria can be obligate or opportunistic parasites of amphibians, capable of inducing localized and systemic infections [ 1 , 86 , 87 ]. Bacterial infections reported in wild and captive amphibians are mainly induced by Gram-negative bacteria [ 1 , 86 ].…”

Section: Co-infection By Homologous Parasitesmentioning

confidence: 99%

“…This is surprising, because in environments other than amphibian hosts, members of these two taxa are often fierce competitors, while they can also be symbionts [ 173 ]. In relation to amphibians specifically, some studies suggest that bacteria may often be the secondary invaders that follow fungal infections [ 1 , 87 ], so that co-infections may occur frequently. Reed et al [ 174 ] observed Chlamydia pneumoniae infection along with Bd in a breeding colony of Xenopus tropicalis , where more than 90 % of the animals died.…”

Section: Co-infection By Heterologous Parasitesmentioning

confidence: 99%

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Host–multiparasite interactions in amphibians: a review

et al. 2021

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Parasites, including viruses, bacteria, fungi, protists, helminths, and arthropods, are ubiquitous in the animal kingdom. Consequently, hosts are frequently infected with more than one parasite species simultaneously. The assessment of such co-infections is of fundamental importance for disease ecology, but relevant studies involving non-domesticated animals have remained scarce. Many amphibians are in decline, and they generally have a highly diverse parasitic fauna. Here we review the literature reporting on field surveys, veterinary case studies, and laboratory experiments on co-infections in amphibians, and we summarize what is known about within-host interactions among parasites, which environmental and intrinsic factors influence the outcomes of these interactions, and what effects co-infections have on hosts. The available literature is piecemeal, and patterns are highly diverse, so that identifying general trends that would fit most host–multiparasite systems in amphibians is difficult. Several examples of additive, antagonistic, neutral, and synergistic effects among different parasites are known, but whether members of some higher taxa usually outcompete and override the effects of others remains unclear. The arrival order of different parasites and the time lag between exposures appear in many cases to fundamentally shape competition and disease progression. The first parasite to arrive can gain a marked reproductive advantage or induce cross-reaction immunity, but by disrupting the skin and associated defences (i.e., skin secretions, skin microbiome) and by immunosuppression, it can also pave the way for subsequent infections. Although there are exceptions, detrimental effects to the host are generally aggravated with increasing numbers of co-infecting parasite species. Finally, because amphibians are ectothermic animals, temperature appears to be the most critical environmental factor that affects co-infections, partly via its influence on amphibian immune function, partly due to its direct effect on the survival and growth of parasites. Besides their importance for our understanding of ecological patterns and processes, detailed knowledge about co-infections is also crucial for the design and implementation of effective wildlife disease management, so that studies concentrating on the identified gaps in our understanding represent rewarding research avenues.

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Section: Co-infection By Homologous Parasitesmentioning

confidence: 99%

Section: Co-infection By Heterologous Parasitesmentioning

confidence: 99%

Host–multiparasite interactions in amphibians: a review

et al. 2021

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“…Emerging infectious diseases (EIDs) are caused by pathogens that have undergone recent changes in terms of geographic spread, increasing incidence, and expanding host range, or by previously unknown pathogens that are being discovered thanks to advances in surveillance and research, particularly in the field of laboratory diagnostics [ 1 ]. Reptiles and amphibians are not protected from the threat of EIDs [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]; in recent years, they have been subject to the emergence of bacterial, viral, fungal, and parasitic diseases that are not only increasingly observed in captivity, but are also responsible for wild population declines: arenavirus, nidovirus, paramyxovirus infections, testudinid intranuclear coccidiosis, ophidiomycosis, paranannizziomycosis, nannizziomycosis, and Emydomyces testavorans infections (in reptiles) [ 3 , 5 , 10 , 13 , 14 , 15 , 16 ], as well as chytridiomycosis (in amphibians) [ 17 , 18 ], cryptosporidiosis, rhabdovirus, adenovirus, iridovirus, ranavirus, and herpesvirus infections (in reptiles and amphibians) [ 3 , 5 , 9 , 10 , 18 ]. This narrative review describes three of the most important emerging fungal diseases of reptiles and amphibians: nannizziomycosis, ophidiomycosis, and chytridiomycosis, as well as how host, pathogen, and environmental characteristics affect the emergence of these diseases.…”

Section: Introductionmentioning

confidence: 99%

Major Emerging Fungal Diseases of Reptiles and Amphibians

Schilliger¹,

Paillusseau²,

François³

et al. 2023

Pathogens

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Emerging infectious diseases (EIDs) are caused by pathogens that have undergone recent changes in terms of geographic spread, increasing incidence, or expanding host range. In this narrative review, we describe three important fungal EIDs with keratin trophism that are relevant to reptile and amphibian conservation and veterinary practice. Nannizziopsis spp. have been mainly described in saurians; infection results in thickened, discolored skin crusting, with eventual progression to deep tissues. Previously only reported in captive populations, it was first described in wild animals in Australia in 2020. Ophidiomyces ophidiicola (formely O. ophiodiicola) is only known to infect snakes; clinical signs include ulcerating lesions in the cranial, ventral, and pericloacal regions. It has been associated with mortality events in wild populations in North America. Batrachochytrium spp. cause ulceration, hyperkeratosis, and erythema in amphibians. They are a major cause of catastrophic amphibian declines worldwide. In general, infection and clinical course are determined by host-related characteristics (e.g., nutritional, metabolic, and immune status), pathogens (e.g., virulence and environmental survival), and environment (e.g., temperature, hygrometry, and water quality). The animal trade is thought to be an important cause of worldwide spread, with global modifications in temperature, hygrometry, and water quality further affecting fungal pathogenicity and host immune response.

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“…When considering viral threats to amphibians, ranaviruses, large, enveloped DNA viruses, are considered one of the major ecological factors contributing to global population declines [ 9 ]. Nidoviruses, medium-large RNA viruses, are also frequently associated with high-mortality outbreaks in reptiles, for example the Bellinger River turtle was almost rendered extinct in 2015 due to an outbreak likely caused by Bellinger River virus [ 10 , 11 ].…”

Section: Introductionmentioning

confidence: 99%

Revealing the uncharacterised diversity of amphibian and reptile viruses

Harding

Russo²,

Yan³

et al. 2022

ISME Communications

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Amphibians and non-avian reptiles represent a significant proportion of terrestrial vertebrates, however knowledge of their viruses is not proportional to their abundance. Many amphibians and reptiles have strict habitual environments and localised populations and are vulnerable to viral outbreaks and potential elimination as a result. We sought to identify viruses that were hidden in amphibian and reptile metatranscriptomic data by screening 235 RNA-sequencing datasets from a 122 species covering 25 countries. We identified 26 novel viruses and eight previously characterised viruses from fifteen different viral families. Twenty-five viruses had RNA genomes with identity to Arteriviridae, Tobaniviridae, Hantaviridae, Rhabdoviridae, Astroviridae, Arenaviridae, Hepeviridae, Picornaviridae, Orthomyxoviridae, Reoviridae, Flaviviridae and Caliciviridae. In addition to RNA viruses, we also screened datasets for DNA viral transcripts, which are commonly excluded from transcriptomic analysis. We identified ten DNA viruses with identity to Papillomaviridae, Parvoviridae, Circoviridae and Adomaviridae. With the addition of these viruses, we expand the global amphibian and reptile virome and identify new potentially pathogenic viruses that could challenge populations. We speculate that amphibian viruses often have simpler genomes than those in amniotes, as in the case of the Secondpapillomavirinae and Orthomyxoviridae viruses identified in this study. In addition, we find evidence of inter-family recombination in RNA viruses, and we also identify new members of the recombinant Adomaviridae family. Overall, we provide insights into the uncharacterised diversity of amphibian and reptile viruses with the aim of improving population management, treatment and conservation into the future.

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Selected Emerging Infectious Diseases of Amphibians

Cited by 10 publications

References 84 publications

Host–multiparasite interactions in amphibians: a review

Host–multiparasite interactions in amphibians: a review

Major Emerging Fungal Diseases of Reptiles and Amphibians

Revealing the uncharacterised diversity of amphibian and reptile viruses

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