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Manenti R, Mercurio S, Melotto A, Barzaghi B, Epis S, Tecilla M, Pennati R, Scarì GU, Ficetola GF. A New Disease Caused by an Unidentified Etiological Agent Affects European Salamanders. Animals (Basel) 2022; 12:ani12060696. [PMID: 35327092 PMCID: PMC8944795 DOI: 10.3390/ani12060696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/03/2022] [Accepted: 03/04/2022] [Indexed: 02/04/2023] Open
Abstract
New pathologies are causing dramatic declines and extinctions of multiple amphibian species. In 2013, in one fire salamander population of Northern Italy, we found individuals with undescribed cysts at the throat level, a malady whose existence has not previously been reported in amphibians. With the aim of describing this novel disease, we performed repeated field surveys to assess the frequency of affected salamanders from 2014 to 2020, and integrated morphological, histological, and molecular analyses to identify the pathogen. The novel disease affected up to 22% of salamanders of the study population and started spreading to nearby populations. Cysts are formed by mucus surrounding protist-like cells about 30 µm long, characterized by numerous cilia/undulipodia. Morphological and genetic analyses did not yield a clear match with described organisms. The existence of this pathogen calls for the implementation of biosecurity protocols and more studies on the dynamics of transmission and the impact on wild populations.
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Affiliation(s)
- Raoul Manenti
- Department of Environmental Science and Policy, University of Milano, 20133 Milano, Italy; (B.B.); (R.P.); (G.F.F.)
- Correspondence: (R.M.); (S.M.); Tel.: +39-3490733107 (R.M.)
| | - Silvia Mercurio
- Department of Environmental Science and Policy, University of Milano, 20133 Milano, Italy; (B.B.); (R.P.); (G.F.F.)
- Correspondence: (R.M.); (S.M.); Tel.: +39-3490733107 (R.M.)
| | - Andrea Melotto
- Centre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch 7602, South Africa;
| | - Benedetta Barzaghi
- Department of Environmental Science and Policy, University of Milano, 20133 Milano, Italy; (B.B.); (R.P.); (G.F.F.)
| | - Sara Epis
- Department of Biosciences, University of Milano, 20133 Milano, Italy; (S.E.); (M.T.); (G.U.S.)
| | - Marco Tecilla
- Department of Biosciences, University of Milano, 20133 Milano, Italy; (S.E.); (M.T.); (G.U.S.)
| | - Roberta Pennati
- Department of Environmental Science and Policy, University of Milano, 20133 Milano, Italy; (B.B.); (R.P.); (G.F.F.)
| | - Giorgio Ulisse Scarì
- Department of Biosciences, University of Milano, 20133 Milano, Italy; (S.E.); (M.T.); (G.U.S.)
| | - Gentile Francesco Ficetola
- Department of Environmental Science and Policy, University of Milano, 20133 Milano, Italy; (B.B.); (R.P.); (G.F.F.)
- Laboratoire d’Ecologie Alpine (LECA), University Grenoble Alpes, CNRS, 38400 Grenoble, France
- Laboratoire d’Ecologie Alpine (LECA), University Savoie Mont Blanc, CNRS, 38400 Grenoble, France
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Herczeg D, Ujszegi J, Kásler A, Holly D, Hettyey A. Host-multiparasite interactions in amphibians: a review. Parasit Vectors 2021; 14:296. [PMID: 34082796 PMCID: PMC8173923 DOI: 10.1186/s13071-021-04796-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 05/20/2021] [Indexed: 01/15/2023] Open
Abstract
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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Affiliation(s)
- Dávid Herczeg
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Herman Ottó út 15, Budapest, 1022, Hungary.
| | - János Ujszegi
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Herman Ottó út 15, Budapest, 1022, Hungary
| | - Andrea Kásler
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Herman Ottó út 15, Budapest, 1022, Hungary.,Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, 1117, Hungary
| | - Dóra Holly
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Herman Ottó út 15, Budapest, 1022, Hungary.,Department of Systematic Zoology and Ecology, Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, 1117, Hungary
| | - Attila Hettyey
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Herman Ottó út 15, Budapest, 1022, Hungary.,Department of Ecology, Institute for Biology, University of Veterinary Medicine, Rottenbiller utca 50, Budapest, 1077, Hungary
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Mihaljevic JR, Polivka CM, Mehmel CJ, Li C, Dukic V, Dwyer G. An Empirical Test of the Role of Small-Scale Transmission in Large-Scale Disease Dynamics. Am Nat 2020; 195:616-635. [PMID: 32216670 DOI: 10.1086/707457] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A key assumption of epidemiological models is that population-scale disease spread is driven by close contact between hosts and pathogens. At larger scales, however, mechanisms such as spatial structure in host and pathogen populations and environmental heterogeneity could alter disease spread. The assumption that small-scale transmission mechanisms are sufficient to explain large-scale infection rates, however, is rarely tested. Here, we provide a rigorous test using an insect-baculovirus system. We fit a mathematical model to data from forest-wide epizootics while constraining the model parameters with data from branch-scale experiments, a difference in spatial scale of four orders of magnitude. This experimentally constrained model fits the epizootic data well, supporting the role of small-scale transmission, but variability is high. We then compare this model's performance to an unconstrained model that ignores the experimental data, which serves as a proxy for models with additional mechanisms. The unconstrained model has a superior fit, revealing a higher transmission rate across forests compared with branch-scale estimates. Our study suggests that small-scale transmission is insufficient to explain baculovirus epizootics. Further research is needed to identify the mechanisms that contribute to disease spread across large spatial scales, and synthesizing models and multiscale data are key to understanding these dynamics.
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Duffus ALJ, Garner TWJ, Nichols RA, Standridge JP, Earl JE. Modelling Ranavirus Transmission in Populations of Common Frogs ( Rana temporaria) in the United Kingdom. Viruses 2019; 11:v11060556. [PMID: 31208063 PMCID: PMC6630962 DOI: 10.3390/v11060556] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 05/31/2019] [Accepted: 06/04/2019] [Indexed: 12/13/2022] Open
Abstract
Ranaviruses began emerging in common frogs (Rana temporaria) in the United Kingdom in the late 1980s and early 1990s, causing severe disease and declines in the populations of these animals. Herein, we explored the transmission dynamics of the ranavirus(es) present in common frog populations, in the context of a simple susceptible-infected (SI) model, using parameters derived from the literature. We explored the effects of disease-induced population decline on the dynamics of the ranavirus. We then extended the model to consider the infection dynamics in populations exposed to both ulcerative and hemorrhagic forms of the ranaviral disease. The preliminary investigation indicated the important interactions between the forms. When the ulcerative form was present in a population and the hemorrhagic form was later introduced, the hemorrhagic form of the disease needed to be highly contagious, to persist. We highlighted the areas where further research and experimental evidence is needed and hope that these models would act as a guide for further research into the amphibian disease dynamics.
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Affiliation(s)
- Amanda L J Duffus
- Department of Mathematics and Natural Sciences, Gordon State College, Barnesville, GA 30204, USA.
| | | | - Richard A Nichols
- School of Biological and Chemical Sciences, Queen Mary, University of London, London E1 4NS, UK.
| | - Joshua P Standridge
- Department of Mathematics and Natural Sciences, Gordon State College, Barnesville, GA 30204, USA.
| | - Julia E Earl
- School of Biological Sciences, Louisiana Tech University, Ruston, LA 71272, USA.
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