• A reservoir species for the emerging amphibian pathogen Batrachochytrium dendrobatidis thrives in a landscape decimated by disease.

      Reeder, N.M.M.; Pessier, Allan P.; Vredenburg, V.T. (2012)
      Chytridiomycosis, a disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is driving amphibian declines and extinctions in protected areas globally. The introduction of invasive reservoir species has been implicated in the spread of Bd but does not explain the appearance of the pathogen in remote protected areas. In the high elevation (>1500 m) Sierra Nevada of California, the native Pacific chorus frog, Pseudacris regilla, appears unaffected by chytridiomycosis while sympatric species experience catastrophic declines. We investigated whether P. regilla is a reservoir of Bd by comparing habitat occupancy before and after a major Bd outbreak and measuring infection in P. regilla in the field, monitoring susceptibility of P. regilla to Bd in the laboratory, examining tissues with histology to determine patterns of infection, and using an innovative soak technique to determine individual output of Bd zoospores in water. Pseudacris regilla persists at 100% of sites where a sympatric species has been extirpated from 72% in synchrony with a wave of Bd. In the laboratory, P. regilla carried loads of Bd as much as an order of magnitude higher than loads found lethal to sympatric species. Histology shows heavy Bd infection in patchy areas next to normal skin, a possible mechanism for tolerance. The soak technique was 77.8% effective at detecting Bd in water and showed an average output of 68 zoospores per minute per individual. The results of this study suggest P. regilla should act as a Bd reservoir and provide evidence of a tolerance mechanism in a reservoir species....
    • Amphibian chytridiomycosis

      Pessier, Allan P.; Divers, S.; Mader, D. (ElsevierSt. Louis, 2014)
    • AMPHIBIAN DISEASES-Batrachochytrium dendrobatidis in Adult Notophthalmus viridescens in North-Central Alabama, USA

      Bakkegard, K. A.; Pessier, Allan P.; (2010)
      ...We report on a haphazard collection of dead adult Notophthalmus viridescens discovered during a field zoology class trip conducted by KAB in Birmingham, Alabama....
    • An enigmatic mortality event in the only population of the Critically Endangered Cameroonian frog Xenopus longipes

      Blackburn, David C.; Evans, Ben J.; Pessier, Allan P.; Vredenburg, Vance T.; (2010)
      Contemporary global declines and mortality events in amphibian populations have been often attributed to infectious disease and climate change, separately and in combination. We report on an enigmatic mortality event in the only known population of the Critically Endangered frog species Xenopus longipes....
    • Batrachochytrium dendrobatidis in Adult Notophthalmus viridescens in North-Central Alabama, USA

      Bakkegard, Kristin; Pessier, Allan P.; (2010)
      ...We report on a haphazard collection of dead adult Notophthalmus viridescens discovered during a field zoology class trip conducted by KAB in Birmingham, Alabama....
    • Climate suitability as a predictor of conservation translocation failure

      Bellis, Joe; Bourke, David; Maschinski, Joyce; Heineman, Katherine D.; Dalrymple, Sarah (2020)
      …We used species distribution models (SDMs) to predict the climate suitability of 102 release sites for amphibians, reptiles and terrestrial insects and compared suitability predictions between successful and failed attempts. We then quantified the importance of climate suitability relative to five other variables frequently considered in the literature to be important determinants of translocation success: number of release years, number of individuals released, life stage released, origin of the source population and position of the release site relative to the species’ range….
    • Clinical trials with itraconazole as a treatment for chytrid fungal infections in amphibians

      Brannelly, L.A.; Richards-Zawacki, C.L.; Pessier, Allan P. (2012)
      Due in large part to recent global declines and extinctions, amphibians are the most threatened vertebrate group. Captive assurance colonies may be the only lifeline for some rapidly disappearing species. Maintaining these colonies free of disease represents a challenge to effective amphibian conservation. The fungal disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is one of the major contributors to global amphibian declines and also poses a serious threat to captive assurance colonies. Many treatment options for Bd infection have not been experimentally tested and the commonly administered dosages of some drugs are known to have negative side effects, highlighting a need for clinical trials. The objective of this study was to clinically test the drug itraconazole as a method for curing Bd infection. We bathed Bd-positive juveniles of 2 anuran amphibian species, Litoria caerulea and Incilius nebulifer, in aqueous itraconazole, varying the concentration and duration of treatment, to find the combination that caused the fewest side effects while also reliably ridding animals of Bd. Our results suggest that a bath in 0.0025% itraconazole for 5 min d?1 for 6 d reliably cures Bd infection and causes fewer side effects than the longer treatment times and higher concentrations of this drug that are commonly administered.
    • Conservation of amphibians and reptiles in the British Virgin Islands: status and patterns

      Perry, G.; Gerber, Glenn P.; Hailey, A.; Wilson, B.S.; Horrocks, J. (Brill Academic PublishersLeiden, The Netherlands, 2011)
      ...Invasive species are still arriving, establishing, and spreading. Thus, although the short-term conservation status of the BVI herpetofauna appears unlikely to change, we are more concerned about the mid-term outlook. We recommend some specific remedies intended to offset these pressures and provide long-term protection to the biota of the BVI
    • Diagnosis and control of amphibian chytridiomycosis

      Pessier, Allan P.; Miller, R. Eric; Fowler, Murray E. (Elsevier SaundersSt. Louis, 2012)
      Chytridiomycosis is an emerging infectious disease associated with global amphibian population dec- lines. The causative agent, Batrachochytrium dendrobatidis (Bd), is a chytrid fungus with a broad host range documented to infect the skin of over 300 different frog and salamander species to date (www.spatialepidemiology.net/bd-maps)....
    • Drought reduces chytrid fungus (batrachochytrium dendrobatidis) infection intensity and mortality but not prevalence in adult crawfish frogs (lithobates areolatus)

      Terrell, Vanessa C. K.; Engbrecht, Nathan J.; Pessier, Allan P.; Lannoo, Michael J. (2014)
      To fully understand the impacts of the chytrid fungus Batrachochytrium dendrobatidis (Bd) on amphibians it is necessary to examine the interactions between populations and their environment. Ecologic variables can exacerbate or ameliorate Bd prevalence and infection intensity, factors that are positively related when Bd is acting on naive amphibian populations as an epidemic disease….
    • Early 1900s Detection of Batrachochytrium dendrobatidis in Korean Amphibians

      Fong, Jonathan J.; Cheng, Tina L.; Bataille, Arnaud; Pessier, Allan P.; Waldman, Bruce; Vredenburg, Vance T. (2015)
      The pathogenic fungus Batrachochytrium dendrobatidis (Bd) is a major conservation concern because of its role in decimating amphibian populations worldwide. We used quantitative PCR to screen 244 museum specimens from the Korean Peninsula, collected between 1911 and 2004, for the presence of Bd to gain insight into its history in Asia. Three specimens of Rugosa emeljanovi (previously Rana or Glandirana rugosa), collected in 1911 from Wonsan, North Korea, tested positive for Bd. Histology of these positive specimens revealed mild hyperkeratosis – a non-specific host response commonly found in Bd-infected frogs – but no Bd zoospores or zoosporangia. Our results indicate that Bd was present in Korea more than 100 years ago, consistent with hypotheses suggesting that Korean amphibians may be infected by endemic Asian Bd strains.
    • Emerging trends for biobanking amphibian genetic resources: The hope, reality and challenges for the next decade

      Kouba, Andrew J.; Lloyd, Rhiannon E.; Houck, Marlys L.; Silla, Aimee J.; Calatayud, Natalie E.; Trudeau, Vance L.; Clulow, John; Molinia, Frank; Langhorne, Cecilia; Vance, Carrie; et al. (2013)
      …Although many institutions have responded by establishing captive assurance colonies for several critically endangered amphibians, the resources provided by these conservation organizations will not be enough to save all species ‘at risk’ without a multi-pronged approach… Several international workshops on amphibian gene banking and assisted reproductive technologies have been held between 2010 and 2012, bringing together leading experts in the fields of amphibian ecology, physiology, and cryobiology to synthesize emerging trends for biobanking amphibian genetic resources, provide opportunities for collaboration, and discuss future research directions.…
    • External reinfection of a fungal pathogen does not contribute to pathogen growth

      DiRenzo, Graziella V.; Tunstall, Tate S.; Ibáñez, Roberto; deVries, Maya S.; Longo, Ana V.; Zamudio, Kelly R.; Lips, Karen R. (2018)
      Chytridiomycosis is an emerging infectious disease of amphibians caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), which has led to devastating declines in amphibian populations worldwide. Current theory predicts that Bd infections are maintained through both reproduction on the host’s skin and reinfection from sources outside of the host....
    • First evidence of amphibian chytrid fungus (Batrachochytrium dendrobatidis) and ranavirus in Hong Kong amphibian trade

      Kolby, Jonathan E.; Smith, Kristine M.; Berger, Lee; Karesh, William B.; Preston, Asa; Pessier, Allan P.; Skerratt, Lee F. (2014)
      The emerging infectious amphibian diseases caused by amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) and ranaviruses are responsible for global amphibian population declines and extinctions. Although likely to have been spread by a variety of activities, transcontinental dispersal appears closely associated with the international trade in live amphibians. The territory of Hong Kong reports frequent, high volume trade in amphibians, and yet the presence of Bd and ranavirus have not previously been detected in either traded or free-ranging amphibians. In 2012, a prospective surveillance project was conducted to investigate the presence of these pathogens in commercial shipments of live amphibians exported from Hong Kong International Airport. Analysis of skin (Bd) and cloacal (ranavirus) swabs by quantitative PCR detected pathogen presence in 31/265 (11.7%) and in 105/185 (56.8%) of amphibians, respectively. In addition, the water in which animals were transported tested positive for Bd, demonstrating the risk of pathogen pollution by the disposal of untreated wastewater. It is uncertain whether Bd and ranavirus remain contained within Hong Kong’s trade sector, or if native amphibians have already been exposed. Rapid response efforts are now urgently needed to determine current pathogen distribution in Hong Kong, evaluate potential trade-associated exposure to free-ranging amphibians, and identify opportunities to prevent disease establishment.
    • Hopping over red leg: The metamorphosis of amphibian pathology

      Pessier, Allan P. (2017)
      It wasn’t very long ago that the only disease of amphibians that students might hear about in veterinary school was “red leg syndrome,” attributed to infections with the bacterium Aeromonas hydrophila.... This would begin to change with recognition of the “Amphibian Extinction Crisis.” ....
    • Integrating current methods for the preservation of amphibian genetic resources and viable tissues to achieve best practices for species conservation

      Zimkus, Breda M; Hassapakis, Craig L; Houck, Marlys L. (2018)
      Global amphibian declines associated with anthropogenic causes, climate change, and amphibianspecific infectious diseases (e.g., chytridiomycosis) have highlighted the importance of biobanking amphibian genetic material. Genetic resource collections were the first to centralize the long-term storage of samples for use in basic science, including disciplines such as molecular evolution, molecular genetics, phylogenetics, and systematics. Biobanks associated with conservation breeding programs put a special emphasis on the cryopreservation of viable cells. These cell lines have a broader application, including the potential for genetic rescue and use in species propagation for population enhancement, such as captive breeding and reintroduction programs. We provide an overview of the most commonly used methods for the preservation of genetic resources, identify ways to standardize collection processes across biobanks, and provide decision trees to assist researchers in maximizing the potential use of their samples for both scientific research and the practice of species conservation. We hope that the collection and deposition of tissues preserved using methods that enable eventual cell line establishment will become routine practice among researchers, particularly herpetologists working in the field. While many major museums do not yet cryopreserve reproductive cells or cell lines, they contain the infrastructure and staff to maintain these collections if protocols and procedures are adapted. Collaboration between organizations can play an important future role in the conservation of amphibians, especially biobanks associated with research institutions and those pioneering techniques used in breeding programs.
    • Isolation of a Bohle-like iridovirus from boreal toads housed within a cosmopolitan aquarium collection

      Cheng, Kwang; Jones, Megan E. B.; Jancovich, James K.; Burchell, Jennifer; Schrenzel, Mark D.; Reavill, Drury R.; Imai, Denise M.; Urban, Abby; Kirkendall, Maryanne; Woods, Leslie W.; et al. (2014)
      A captive ‘survival assurance’ population of 56 endangered boreal toads Anaxyrus boreas boreas, housed within a cosmopolitan collection of amphibians originating from Southeast Asia and other locations, experienced high mortality (91%) in April to July 2010. Histological examination demonstrated lesions consistent with ranaviral disease, including multicentric necrosis of skin, kidney, liver, spleen, and hematopoietic tissue, vasculitis, and myriad basophilic intracytoplasmic inclusion bodies…. This finding has implications for the management of amphibians destined for use in reintroduction programs, as their release may inadvertently lead to viral dissemination.
    • Leaping forward in amphibian health and nutrition

      Olea-Popelka, Francisco; Ferrie, Gina M.; Morris, Cheryl; Pessier, Allan P.; Schad, Kristine; Stamper, M. Andrew; Gagliardo, Ron; Koutsos, Elizabeth; Valdes, Eduardo V. (2014)
      …In this manuscript, we describe and summarize the outcomes of this workshop with regards (a) the identified gaps in knowledge, (b) identified priorities for closing these gaps, and (c) compile a list of actions to address these priorities. Four general areas of improvement were identified in relation to how measurements are currently being taken to evaluate ex situ amphibian health: nutrition, infectious diseases, husbandry, and integrated biology including genetics and endocrinology….
    • Moving towards greater success in translocations: recent advances from the herpetofauna

      Germano, Jennifer M.; Ewen, J. G.; Mushinsky, H.; McCoy, E.; Ortiz-Catedral, L. (2014)
      ...While the idea of moving an animal may seem simple at first glance, the reality is that translocations are inherently complex. In order to improve our rates of success, this complexity must be considered....