The Experts below are selected from a list of 1863 Experts worldwide ranked by ideXlab platform
Trenton W. J. Garner - One of the best experts on this subject based on the ideXlab platform.
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Common midwife toad Ranaviruses replicate first in the oral cavity of smooth newts (Lissotriton vulgaris) and show distinct strain-associated pathogenicity
Scientific Reports, 2019Co-Authors: Bernardo Saucedo, Steven J. R. Allain, Mark J. Goodman, Raymond J. Cranfield, Diego A. Vergara, N Kruithof, Maria J Forzan, Chris Sergeant, Trenton W. J. Garner, Steven J. BeurdenAbstract:Ranavirus is the second most common infectious cause of amphibian mortality. These viruses affect caudates, an order in which information regarding Ranavirus pathogenesis is scarce. In the Netherlands, two strains (CMTV-NL I and III) were suspected to possess distinct pathogenicity based on field data. To investigate susceptibility and disease progression in urodeles and determine differences in pathogenicity between strains, 45 adult smooth newts ( Lissotriton vulgaris ) were challenged via bath exposure with these Ranaviruses and their detection in organs and feces followed over time by PCR, immunohistochemistry and in situ hybridization. Ranavirus was first detected at 3 days post infection (p.i.) in the oral cavity and upper respiratory mucosa. At 6 days p.i, virus was found in connective tissues and vasculature of the gastrointestinal tract. Finally, from 9 days p.i onwards there was widespread Ranavirus disease in various organs including skin, kidneys and gonads. Higher pathogenicity of the CMTV-NL I strain was confirmed by higher correlation coefficient of experimental group and mortality of challenged animals. Ranavirus -exposed smooth newts shed virus in feces intermittently and infection was seen in the absence of lesions or clinical signs, indicating that this species can harbor subclinical infections and potentially serve as disease reservoirs.
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A de novo Assembly of the Common Frog (Rana temporaria) Transcriptome and Comparison of Transcription Following Exposure to Ranavirus and Batrachochytrium dendrobatidis
PloS one, 2015Co-Authors: Stephen J. Price, Trenton W. J. Garner, Francois Balloux, Chris Ruis, Konrad Paszkiewicz, Karen Moore, Amber G. F. GriffithsAbstract:Amphibians are experiencing global declines and extinctions, with infectious diseases representing a major factor. In this study we examined the transcriptional response of metamorphic hosts (common frog, Rana temporaria) to the two most important amphibian pathogens: Batrachochytrium dendrobatidis (Bd) and Ranavirus. We found strong up-regulation of a gene involved in the adaptive immune response (AP4S1) at four days post-exposure to both pathogens. We detected a significant transcriptional response to Bd, covering the immune response (innate and adaptive immunity, complement activation, and general inflammatory responses), but relatively little transcriptional response to Ranavirus. This may reflect the higher mortality rates found in wild common frogs infected with Ranavirus as opposed to Bd. These data provide a valuable genomic resource for the amphibians, contribute insight into gene expression changes after pathogen exposure, and suggest potential candidate genes for future host-pathogen research.
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assessing the long term impact of Ranavirus infection in wild common frog populations
Animal Conservation, 2010Co-Authors: Amber G. F. Teacher, Andrew A. Cunningham, Trenton W. J. GarnerAbstract:Amphibians are declining worldwide, and one cause of this is infectious disease emergence. Mass mortalities caused by a virus or a group of viruses belonging to the genus Ranavirus have occurred in wild common frogs Rana temporaria in England since the 1980s, and ranaviral disease is widespread in amphibians in North America and Canada, where it can also cause mass die-offs. Although there have been numerous reports of Ranavirus-associated mass mortality events, no study has yet evaluated the long-term impacts of this disease. This study follows up archived records of English common frog mortalities likely caused by Ranavirus. There is a preliminary indication that common frog populations can respond differently to the emergence of disease: emergence may be transient, catastrophic, or persistent with recurrent mortality events. We subsequently focused on populations that had recurring mortality events (n = 18), and we report median declines of 81% in the number of adult frogs in these populations from 1996 to 2008. Comparable uninfected populations (n = 16) showed no change in population size over the same time period. Regressions show that larger frog populations may be more likely to experience larger declines than smaller populations, and linear models show that percentage population size change is significantly correlated with disease status, but that habitat age (a possible proxy for environmental quality) has no significant effect on population size change. Our results provide the first evidence of long-term localized population declines of an amphibian species which appear to be best explained by the presence of Ranavirus infection.
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Assessing the long‐term impact of Ranavirus infection in wild common frog populations
Animal Conservation, 2010Co-Authors: Amber G. F. Teacher, Andrew A. Cunningham, Trenton W. J. GarnerAbstract:Amphibians are declining worldwide, and one cause of this is infectious disease emergence. Mass mortalities caused by a virus or a group of viruses belonging to the genus Ranavirus have occurred in wild common frogs Rana temporaria in England since the 1980s, and ranaviral disease is widespread in amphibians in North America and Canada, where it can also cause mass die-offs. Although there have been numerous reports of Ranavirus-associated mass mortality events, no study has yet evaluated the long-term impacts of this disease. This study follows up archived records of English common frog mortalities likely caused by Ranavirus. There is a preliminary indication that common frog populations can respond differently to the emergence of disease: emergence may be transient, catastrophic, or persistent with recurrent mortality events. We subsequently focused on populations that had recurring mortality events (n = 18), and we report median declines of 81% in the number of adult frogs in these populations from 1996 to 2008. Comparable uninfected populations (n = 16) showed no change in population size over the same time period. Regressions show that larger frog populations may be more likely to experience larger declines than smaller populations, and linear models show that percentage population size change is significantly correlated with disease status, but that habitat age (a possible proxy for environmental quality) has no significant effect on population size change. Our results provide the first evidence of long-term localized population declines of an amphibian species which appear to be best explained by the presence of Ranavirus infection.
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RESPONSE OF THE ITALIAN AGILE FROG (RANA LATASTEI) TO A Ranavirus, FROG VIRUS 3: A MODEL FOR VIRAL EMERGENCE IN NAIVE POPULATIONS
Journal of wildlife diseases, 2004Co-Authors: Peter B. Pearman, Trenton W. J. Garner, Monika Straub, Urs F. GreberAbstract:Ranavirus (family Iridoviridae) is a genus of pathogens of poikilotherms, and some Ranaviruses may play a role in widespread mortality of amphibians. Ecology of viral transmission in amphibians is poorly known but can be addressed through experimentation in the laboratory. In this study, we use the Ranavirus frog virus 3 (FV3) as an experimental model for pathogen emergence in naive populations of tadpoles. We simulated emerging disease by exposing tadpoles of the Italian agile frog (Rana latastei), to the North American Ranavirus FV3. We demonstrated that mortality occurred due to viral exposure, exposure of tadpoles to decreasing concentrations of FV3 in the laboratory produced dose-dependent survival rates, and cannibalism of virus-carrying carcasses increased mortality due to FV3. These experiments suggest the potential for ecological mechanisms to affect the level of exposure of tadpoles to Ranavirus and to impact transmission of viral pathogens in aquatic systems.
Andrew A. Cunningham - One of the best experts on this subject based on the ideXlab platform.
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Screening of a long-term sample set reveals two Ranavirus lineages in British herpetofauna.
PloS one, 2017Co-Authors: Stephen J. Price, Andrew A. Cunningham, Alexandra Wadia, Owen N. Wright, William T. M. Leung, Becki LawsonAbstract:Reports of severe disease outbreaks in amphibian communities in mainland Europe due to strains of the common midwife toad virus (CMTV)-like clade of Ranavirus are increasing and have created concern due to their considerable population impacts. In Great Britain, viruses in another clade of Ranavirus–frog virus 3 (FV3)-like—have caused marked declines of common frog (Rana temporaria) populations following likely recent virus introductions. The British public has been reporting mortality incidents to a citizen science project since 1992, with carcasses submitted for post-mortem examination, resulting in a long-term tissue archive spanning 25 years. We screened this archive for Ranavirus (458 individuals from 228 incidents) using molecular methods and undertook preliminary genotyping of the Ranaviruses detected. In total, Ranavirus was detected in 90 individuals from 41 incidents focused in the north and south of England. The majority of detections involved common frogs (90%) but also another anuran, a caudate and a reptile. Most incidents were associated with FV3-like viruses but two, separated by 300 km and 16 years, involved CMTV-like viruses. These British CMTV-like viruses were more closely related to Ranaviruses from mainland Europe than to each other and were estimated to have diverged at least 458 years ago. This evidence of a CMTV-like virus in Great Britain in 1995 represents the earliest confirmed case of a CMTV associated with amphibians and raises important questions about the history of Ranavirus in Great Britain and the epidemiology of CMTV-like viruses. Despite biases present in the opportunistic sample used, this study also demonstrates the role of citizen science projects in generating resources for research and the value of maintaining long-term wildlife tissue archives.
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assessing the long term impact of Ranavirus infection in wild common frog populations
Animal Conservation, 2010Co-Authors: Amber G. F. Teacher, Andrew A. Cunningham, Trenton W. J. GarnerAbstract:Amphibians are declining worldwide, and one cause of this is infectious disease emergence. Mass mortalities caused by a virus or a group of viruses belonging to the genus Ranavirus have occurred in wild common frogs Rana temporaria in England since the 1980s, and ranaviral disease is widespread in amphibians in North America and Canada, where it can also cause mass die-offs. Although there have been numerous reports of Ranavirus-associated mass mortality events, no study has yet evaluated the long-term impacts of this disease. This study follows up archived records of English common frog mortalities likely caused by Ranavirus. There is a preliminary indication that common frog populations can respond differently to the emergence of disease: emergence may be transient, catastrophic, or persistent with recurrent mortality events. We subsequently focused on populations that had recurring mortality events (n = 18), and we report median declines of 81% in the number of adult frogs in these populations from 1996 to 2008. Comparable uninfected populations (n = 16) showed no change in population size over the same time period. Regressions show that larger frog populations may be more likely to experience larger declines than smaller populations, and linear models show that percentage population size change is significantly correlated with disease status, but that habitat age (a possible proxy for environmental quality) has no significant effect on population size change. Our results provide the first evidence of long-term localized population declines of an amphibian species which appear to be best explained by the presence of Ranavirus infection.
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Assessing the long‐term impact of Ranavirus infection in wild common frog populations
Animal Conservation, 2010Co-Authors: Amber G. F. Teacher, Andrew A. Cunningham, Trenton W. J. GarnerAbstract:Amphibians are declining worldwide, and one cause of this is infectious disease emergence. Mass mortalities caused by a virus or a group of viruses belonging to the genus Ranavirus have occurred in wild common frogs Rana temporaria in England since the 1980s, and ranaviral disease is widespread in amphibians in North America and Canada, where it can also cause mass die-offs. Although there have been numerous reports of Ranavirus-associated mass mortality events, no study has yet evaluated the long-term impacts of this disease. This study follows up archived records of English common frog mortalities likely caused by Ranavirus. There is a preliminary indication that common frog populations can respond differently to the emergence of disease: emergence may be transient, catastrophic, or persistent with recurrent mortality events. We subsequently focused on populations that had recurring mortality events (n = 18), and we report median declines of 81% in the number of adult frogs in these populations from 1996 to 2008. Comparable uninfected populations (n = 16) showed no change in population size over the same time period. Regressions show that larger frog populations may be more likely to experience larger declines than smaller populations, and linear models show that percentage population size change is significantly correlated with disease status, but that habitat age (a possible proxy for environmental quality) has no significant effect on population size change. Our results provide the first evidence of long-term localized population declines of an amphibian species which appear to be best explained by the presence of Ranavirus infection.
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Experimental transmission of a Ranavirus disease of common toads (Bufo bufo) to common frogs (Rana temporaria).
Epidemiology and infection, 2007Co-Authors: Andrew A. Cunningham, Alex D. Hyatt, P. Russell, Peter M. BennettAbstract:During investigations of epidemic frog mortality in Britain, a novel fatal systemic haemorrhagic disease of common toads was discovered. This disease resembles a systemic haemorrhagic disease of common frogs in Britain, which is one of a range of fatal disease syndromes, characterized by systemic haemorrhages, skin ulceration or a combination of these lesions, caused by Ranavirus infection. Ranavirus previously isolated from diseased toads was inoculated into common frogs to evaluate if this virus could infect and cause disease in common frogs. All virus-inoculated frogs died with systemic haemorrhages between 6 and 8 days post-inoculation, giving similar results to those produced by the inoculation of frogs with Ranavirus cultured from naturally diseased frogs. These results indicate that the same, or similar, viruses are affecting both frogs and toads in the field and confirm that Ranavirus has emerged as an important cause of amphibian mortality in Britain.
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Emerging epidemic diseases of frogs in Britain are dependent on the source of Ranavirus agent and the route of exposure.
Epidemiology and infection, 2006Co-Authors: Andrew A. Cunningham, Alex D. Hyatt, P. Russell, Peter M. BennettAbstract:A series of transmission studies was conducted to investigate the aetiology, or aetiologies, of emerging fatal epidemic disease syndromes affecting the common frog (Rana temporaria) in Britain. The syndromes, characterized by skin ulceration or systemic haemorrhages, were induced upon exposure to lesion homogenates or cultured Ranavirus. The re-isolation of Ranavirus from experimentally affected frogs fulfilled Koch's postulates. Aeromonas hydrophila, previously associated with similar lesions, was not significant to disease development. Unexpectedly, disease outcomes were influenced by both the source of agent and the route of exposure, indicating that different Ranaviruses with different tissue tropisms and pathogeneses (possibly similar to quasi-species in RNA virus populations) are circulating in the British common frog population. Our findings confirm that Ranavirus disease has emerged as an important cause of amphibian mortality in Britain.
Debra L. Miller - One of the best experts on this subject based on the ideXlab platform.
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Water sports could contribute to the translocation of Ranaviruses
Nature Publishing Group, 2019Co-Authors: Rosa Casais, Debra L. Miller, Matthew J. Gray, Asier R. Larrinaga, Kevin P. Dalton, Paula Domínguez Lapido, Isabel Márquez, Eloy Bécares, Davis E. Carter, Ana BalseiroAbstract:Abstract Ranaviruses have been identified as the cause of explosive disease outbreaks in amphibians worldwide and can be transmitted between hosts both via direct and indirect contact, in which humans might contribute to the translocation of contaminated material. The aim of this study was to evaluate the possible role of water sports in the human translocation of Ranavirus, Batrachochytrium dendrobatidis (Bd), and B. salamandrivorans (Bsal). A total of 234 boats were sampled during the spring Spanish Canoe Championship which took place in Pontillón de Castro, a reservoir with a history of ranavirosis, in May 2017. Boats were tested for the presence of Ranavirus and Batrachochytrium spp. DNA, using quantitative real-time polymerase chain reaction techniques (qPCR). A total of 22 swabs (22/234, 9.40%) yielded qPCR-positive results for Ranavirus DNA while Bd or Bsal were not detected in any of the samples. We provide the first evidence that human-related water sports could be a source of Ranavirus contamination, providing justification for public disinfecting stations in key areas where human traffic from water sports is high
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Poor biosecurity could lead to disease outbreaks in animal populations
2018Co-Authors: Matthew J. Gray, Rebecca P. Wilkes, Davis E. Carter, Jennifer A. Spatz, Christian M. Yarber, Debra L. MillerAbstract:Human-mediated disease outbreaks due to poor biosecurity practices when processing animals in wild populations have been suspected. We tested whether not changing nitrile gloves between processing wood frog (Lithobates sylvaticus) tadpoles and co-housing individuals increased pathogen transmission and subsequent diseased-induced mortality caused by the emerging pathogen, Ranavirus. We found that not changing gloves between processing infected and uninfected tadpoles resulted in transmission of Ranavirus and increased the risk of mortality of uninfected tadpoles by 30X. Co-housing tadpoles for only 15 minutes with 10% of individuals infected resulted in Ranavirus transmission and 50% mortality of uninfected tadpoles. More extreme mortality was observed when the co-housing infection prevalence was >10%. Our results illustrate that human-induced disease outbreaks due to poor biosecurity practices are possible in wild animal populations.
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Ranavirus could facilitate local extinction of rare amphibian species
Oecologia, 2016Co-Authors: Julia E. Earl, William B. Sutton, Jordan C. Chaney, Carson E. Lillard, Andrew J. Kouba, Cecilia J. Langhorne, Jessi Krebs, Rebecca P. Wilkes, Rachel D. Hill, Debra L. MillerAbstract:There is growing evidence that pathogens play a role in population declines and species extinctions. For small populations, disease-induced extinction may be especially probable. We estimated the susceptibility of two amphibian species of conservation concern (the dusky gopher frog [Lithobates sevosus] and boreal toad [Anaxyrus boreas boreas]) to an emerging pathogen (Ranavirus) using laboratory challenge experiments, and combined these data with published demographic parameter estimates to simulate the potential effects of Ranavirus exposure on extinction risk. We included effects of life stage during pathogen exposure, pathogen exposure interval, hydroperiod of breeding habitat, population carrying capacity, and immigration in simulations. We found that both species were highly susceptible to Ranavirus when exposed to the pathogen in water at environmentally relevant concentrations. Dusky gopher frogs experienced 100 % mortality in four of six life stages tested. Boreal toads experienced 100 % mortality when exposed as tadpoles or metamorphs, which were the only life stages tested. Simulations showed population declines, greater extinction probability, and faster times to extinction with Ranavirus exposure. These effects were more evident with more frequent pathogen exposure intervals and lower carrying capacity. Immigration at natural rates did little to mitigate effects of Ranavirus exposure unless immigration occurred every 2 years. Our results demonstrate that disease-induced extinction by emerging pathogens, such as Ranavirus, is possible, and that threat may be especially high for species with small population sizes. For the species in this study, conservation organizations should incorporate Ranavirus surveillance into monitoring programs and devise intervention strategies in the event that disease outbreaks occur.
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Trends in Ranavirus Prevalence Among Plethodontid Salamanders in the Great Smoky Mountains National Park
EcoHealth, 2014Co-Authors: William B. Sutton, Matthew J. Gray, Jason T. Hoverman, Richard G. Secrist, Paul E. Super, Rebecca H. Hardman, Jennifer L. Tucker, Debra L. MillerAbstract:Emerging pathogens are a potential contributor to global amphibian declines. Ranaviruses, which infect ectothermic vertebrates and are common in aquatic environments, have been implicated in die-offs of at least 72 amphibian species worldwide. Most studies on the subject have focused on pool-breeding amphibians, and infection trends in other amphibian species assemblages have been understudied. Our primary study objective was to evaluate hypotheses explaining Ranavirus prevalence within a lungless salamander assemblage (Family Plethodontidae) in the Great Smoky Mountains National Park, USA. We sampled 566 total plethodontid salamanders representing 14 species at five sites over a 6-year period (2007–2012). We identified Ranavirus-positive individuals in 11 of the 14 (78.6%) sampled species, with salamanders in the genus Desmognathus having greatest infection prevalence. Overall, we found the greatest support for site elevation and sampling year determining infection prevalence. We detected the greatest number of infections in 2007 with 82.5% of sampled individuals testing positive for Ranavirus, which we attribute to record drought during this year. Infection prevalence remained relatively high in low-elevation sites in 2008 and 2009. Neither body condition nor aquatic dependence was a significant predictor of Ranavirus prevalence. Overall, our results indicate that life history differences among species play a minor role determining Ranavirus prevalence compared to the larger effects of site elevation and yearly fluctuations (likely due to environmental stressors) during sampling years.
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High susceptibility of the endangered dusky gopher frog to Ranavirus.
Diseases of aquatic organisms, 2014Co-Authors: William B. Sutton, Matthew J. Gray, Rebecca H. Hardman, Andrew J. Kouba, Rebecca P. Wilkes, Debra L. MillerAbstract:Amphibians are one of the most imperiled vertebrate groups, with pathogens playing a role in the decline of some species. Rare species are particularly vulnerable to extinction be - cause populations are often isolated and exist at low abundance. The potential impact of patho- gens on rare amphibian species has seldom been investigated. The dusky gopher frog Lithobates sevosus is one of the most endangered amphibian species in North America, with 100�200 indi- viduals remaining in the wild. Our goal was to determine whether adult L. sevosus were suscep- tible to Ranavirus, a pathogen responsible for amphibian die-offs worldwide. We tested the rela- tive susceptibility of adult L. sevosus to Ranavirus (10 3 plaque-forming units) isolated from a morbid bullfrog via 3 routes of exposure: intra-coelomic (IC) injection, oral (OR) inoculation, and water bath (WB) exposure. We observed 100% mortality of adult L. sevosus in the IC and WB treatments after 10 and 19 d, respectively. Ninety-five percent mortality occurred in the OR treat- ment over the 28 d evaluation period. No mortality was observed in the control treatment after 28 d. Our results indicate that L. sevosus is susceptible to Ranavirus, and if adults in the wild are exposed to this pathogen, significant mortality could occur. Additionally, our study demonstrates that some adult amphibian species can be very susceptible to Ranavirus, which has been often overlooked in North American studies. We recommend that conservation planners consider test- ing the susceptibility of rare amphibian species to Ranavirus and that the adult age class is included in future challenge experiments.
Matthew J. Gray - One of the best experts on this subject based on the ideXlab platform.
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Water sports could contribute to the translocation of Ranaviruses
Nature Publishing Group, 2019Co-Authors: Rosa Casais, Debra L. Miller, Matthew J. Gray, Asier R. Larrinaga, Kevin P. Dalton, Paula Domínguez Lapido, Isabel Márquez, Eloy Bécares, Davis E. Carter, Ana BalseiroAbstract:Abstract Ranaviruses have been identified as the cause of explosive disease outbreaks in amphibians worldwide and can be transmitted between hosts both via direct and indirect contact, in which humans might contribute to the translocation of contaminated material. The aim of this study was to evaluate the possible role of water sports in the human translocation of Ranavirus, Batrachochytrium dendrobatidis (Bd), and B. salamandrivorans (Bsal). A total of 234 boats were sampled during the spring Spanish Canoe Championship which took place in Pontillón de Castro, a reservoir with a history of ranavirosis, in May 2017. Boats were tested for the presence of Ranavirus and Batrachochytrium spp. DNA, using quantitative real-time polymerase chain reaction techniques (qPCR). A total of 22 swabs (22/234, 9.40%) yielded qPCR-positive results for Ranavirus DNA while Bd or Bsal were not detected in any of the samples. We provide the first evidence that human-related water sports could be a source of Ranavirus contamination, providing justification for public disinfecting stations in key areas where human traffic from water sports is high
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Poor biosecurity could lead to disease outbreaks in animal populations
2018Co-Authors: Matthew J. Gray, Rebecca P. Wilkes, Davis E. Carter, Jennifer A. Spatz, Christian M. Yarber, Debra L. MillerAbstract:Human-mediated disease outbreaks due to poor biosecurity practices when processing animals in wild populations have been suspected. We tested whether not changing nitrile gloves between processing wood frog (Lithobates sylvaticus) tadpoles and co-housing individuals increased pathogen transmission and subsequent diseased-induced mortality caused by the emerging pathogen, Ranavirus. We found that not changing gloves between processing infected and uninfected tadpoles resulted in transmission of Ranavirus and increased the risk of mortality of uninfected tadpoles by 30X. Co-housing tadpoles for only 15 minutes with 10% of individuals infected resulted in Ranavirus transmission and 50% mortality of uninfected tadpoles. More extreme mortality was observed when the co-housing infection prevalence was >10%. Our results illustrate that human-induced disease outbreaks due to poor biosecurity practices are possible in wild animal populations.
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THIRD INTERNATIONAL SYMPOSIUM ON RanavirusES:: ADVANCING THE UNDERSTANDING OF THE THREAT OF RanavirusES TO NORTH AMERICAN HERPETOFAUNA
Journal of North American Herpetology, 2017Co-Authors: Amanda L. J. Duffus, V. Gregory Chinchar, Matthew J. Gray, Patricia Johnson, Thomas B WaltzekAbstract:Members of the genus Ranavirus, one of five genera withinthe family Iridoviridae, encompass a group of large, doublestrandedDNA viruses that infect all three classes of ectothermicvertebrates: fish, amphibians, and reptiles. Ranaviruses areglobally emerging pathogens that cause considerable morbidityand mortality among diverse populations. In North America,Ranavirus epizootics are regularly reported in wild and culturedfish, amphibian, and reptile populations.
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Ranavirus Ecology and Evolution: From Epidemiology to Extinction
Ranaviruses, 2015Co-Authors: Jesse L. Brunner, Matthew J. Gray, Andrew Storfer, Jason T. HovermanAbstract:Ranaviruses have been identified in wild and captive populations of ectothermic vertebrates around the world. Ranavirus epidemics can result in a range of effects on their host populations, from apparently benign infections to mass mortality and local extirpation. In this chapter, we review the current status of Ranavirus epidemiology and ecology in amphibians, fish, and reptiles. Ranavirus epidemics in amphibians and fish usually have a rapid onset in the mid-to-late summer while outbreaks in reptiles occur irregularly. Susceptibility to Ranavirus differs among host species, and may be influenced by the type of Ranavirus and natural or anthropogenic stressors. Ranaviruses can be transmitted within and between host species via several routes, but there is a need for transmission estimates in natural environments. Generally, Ranaviruses are locally adapted to their host populations, but movement of infected hosts over long distances can disrupt these associations. There is evidence of increased virulence of Ranaviruses in captive fish and amphibian populations raised for production. Given their broad host ranges, potential for high virulence, multiple routes of transmission, and frequent movement of amphibians, fish and reptiles in global trade, it appears that some Ranaviruses have the potential to significantly impact host populations and even cause extinctions in the wild.
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Design and Analysis of Ranavirus Studies: Surveillance and Assessing Risk
Ranaviruses, 2015Co-Authors: Matthew J. Gray, Jesse L. Brunner, Julia E. Earl, Ellen ArielAbstract:Ranaviruses are pathogens that cause disease in ectothermic vertebrate species, and are responsible for die-off events in multiple taxa across the globe. Understanding the threat of Ranavirus in wild and captive populations is a growing conservation and economic interest. Quantifying risk is a central premise to understanding the threat of a pathogen, and surveillance studies are a logical starting point. In this chapter, we discuss how to design surveillance studies for Ranavirus, required sample sizes, statistical analyses commonly used to analyze data, and modeling approaches to predict disease outcomes. Additionally, we cover the process of Import Risk Analysis, which quantifies the threat of Ranavirus introduction into a new area. The principles discussed herein will help organizations and investigators document the distribution of Ranaviruses, identify hotspots of infection and disease, determine factors associated with emergence, and collect data necessary to determine practical intervention strategies.
Amber G. F. Teacher - One of the best experts on this subject based on the ideXlab platform.
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assessing the long term impact of Ranavirus infection in wild common frog populations
Animal Conservation, 2010Co-Authors: Amber G. F. Teacher, Andrew A. Cunningham, Trenton W. J. GarnerAbstract:Amphibians are declining worldwide, and one cause of this is infectious disease emergence. Mass mortalities caused by a virus or a group of viruses belonging to the genus Ranavirus have occurred in wild common frogs Rana temporaria in England since the 1980s, and ranaviral disease is widespread in amphibians in North America and Canada, where it can also cause mass die-offs. Although there have been numerous reports of Ranavirus-associated mass mortality events, no study has yet evaluated the long-term impacts of this disease. This study follows up archived records of English common frog mortalities likely caused by Ranavirus. There is a preliminary indication that common frog populations can respond differently to the emergence of disease: emergence may be transient, catastrophic, or persistent with recurrent mortality events. We subsequently focused on populations that had recurring mortality events (n = 18), and we report median declines of 81% in the number of adult frogs in these populations from 1996 to 2008. Comparable uninfected populations (n = 16) showed no change in population size over the same time period. Regressions show that larger frog populations may be more likely to experience larger declines than smaller populations, and linear models show that percentage population size change is significantly correlated with disease status, but that habitat age (a possible proxy for environmental quality) has no significant effect on population size change. Our results provide the first evidence of long-term localized population declines of an amphibian species which appear to be best explained by the presence of Ranavirus infection.
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Assessing the long‐term impact of Ranavirus infection in wild common frog populations
Animal Conservation, 2010Co-Authors: Amber G. F. Teacher, Andrew A. Cunningham, Trenton W. J. GarnerAbstract:Amphibians are declining worldwide, and one cause of this is infectious disease emergence. Mass mortalities caused by a virus or a group of viruses belonging to the genus Ranavirus have occurred in wild common frogs Rana temporaria in England since the 1980s, and ranaviral disease is widespread in amphibians in North America and Canada, where it can also cause mass die-offs. Although there have been numerous reports of Ranavirus-associated mass mortality events, no study has yet evaluated the long-term impacts of this disease. This study follows up archived records of English common frog mortalities likely caused by Ranavirus. There is a preliminary indication that common frog populations can respond differently to the emergence of disease: emergence may be transient, catastrophic, or persistent with recurrent mortality events. We subsequently focused on populations that had recurring mortality events (n = 18), and we report median declines of 81% in the number of adult frogs in these populations from 1996 to 2008. Comparable uninfected populations (n = 16) showed no change in population size over the same time period. Regressions show that larger frog populations may be more likely to experience larger declines than smaller populations, and linear models show that percentage population size change is significantly correlated with disease status, but that habitat age (a possible proxy for environmental quality) has no significant effect on population size change. Our results provide the first evidence of long-term localized population declines of an amphibian species which appear to be best explained by the presence of Ranavirus infection.
