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0000-0003-3471-7512
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Veterinary Sciences | Veterinary Immunology | Veterinary Epidemiology | Veterinary Microbiology (excl. Virology) | Host-Parasite Interactions | Molecular Evolution | Wildlife and Habitat Management | Mycology | Terrestrial Ecology | Animal Breeding | Epidemiology |
ANZSRC Socio-Economic Objective (SEO)
Control of Pests, Diseases and Exotic Species at Regional or Larger Scales | Flora, Fauna and Biodiversity at Regional or Larger Scales | Living resources (flora and fauna) | Trade and environment | Control of pests and exotic species | Control of Pests, Diseases and Exotic Species in Mountain and High Country Environments
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Publications
Hendra Virus Spillover is a Bimodal System Driven by Climatic Factors
Publisher: Springer Science and Business Media LLC
Date: 18-01-2018
DOI: 10.1007/S10393-017-1309-Y
Abstract: Understanding environmental factors driving spatiotemporal patterns of disease can improve risk mitigation strategies. Hendra virus (HeV), discovered in Australia in 1994, spills over from bats (Pteropus sp.) to horses and thence to humans. Below latitude - 22°, almost all spillover events to horses occur during winter, and above this latitude spillover is aseasonal. We generated a statistical model of environmental drivers of HeV spillover per month. The model reproduced the spatiotemporal pattern of spillover risk between 1994 and 2015. The model was generated with an ensemble of methods for presence-absence data (boosted regression trees, random forests and logistic regression). Presences were the locations of horse cases, and absences per spatial unit (2.7 × 2.7 km pixels without spillover) were s led with the horse census of Queensland and New South Wales. The most influential factors indicate that spillover is associated with both cold-dry and wet conditions. Bimodal responses to several variables suggest spillover involves two systems: one above and one below a latitudinal area close to - 22°. Northern spillovers are associated with cold-dry and wet conditions, and southern with cold-dry conditions. Biologically, these patterns could be driven by immune or behavioural changes in response to food shortage in bats and horse husbandry. Future research should look for differences in these traits between seasons in the two latitudinal regions. Based on the predicted risk patterns by latitude, we recommend enhanced preventive management for horses from March to November below latitude 22° south.
Issues with modelling the current and future distribution of invasive pathogens
Publisher: Wiley
Date: 17-12-2010
Airborne lead dust concentration in townsville, queensland is associated with port activity and May contribute to estuarine Sediment Contamination
Publisher: Elsevier BV
Date: 09-2019
Response to Comment on “Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity”
Publisher: American Association for the Advancement of Science (AAAS)
Date: 20-03-2020
Abstract: Lambert et al . question our retrospective and holistic epidemiological assessment of the role of chytridiomycosis in hibian declines. Their alternative assessment is narrow and provides an incomplete evaluation of evidence. Adopting this approach limits understanding of infectious disease impacts and h ers conservation efforts. We reaffirm that our study provides unambiguous evidence that chytridiomycosis has affected at least 501 hibian species.
History and recent progress on chytridiomycosis in amphibians
Publisher: Elsevier BV
Date: 02-2016
Correction: Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Wild Amphibian Populations in Madagascar
Publisher: Public Library of Science (PLoS)
Date: 29-07-2015
Evolution of resistance to chytridiomycosis is associated with a robust early immune response
Publisher: Wiley
Date: 02-2018
DOI: 10.1111/MEC.14493
Abstract: Potentiating the evolution of immunity is a promising strategy for addressing bio ersity diseases. Assisted selection for infection resistance may enable the recovery and persistence of hibians threatened by chytridiomycosis, a devastating fungal skin disease threatening hundreds of species globally. However, knowledge of the mechanisms involved in the natural evolution of immunity to chytridiomycosis is limited. Understanding the mechanisms of such resistance may help speed-assisted selection. Using a transcriptomics approach, we examined gene expression responses of endangered alpine tree frogs (Litoria verreauxii alpina) to subclinical infection, comparing two long-exposed populations with a naïve population. We performed a blinded, randomized and controlled exposure experiment, collecting skin, liver and spleen tissues at 4, 8 and 14 days postexposure from 51 wild-caught captively reared infection-naïve adult frogs for transcriptome assembly and differential gene expression analyses. We analysed our results in conjunction with infection intensity data, and the results of a large clinical survival experiment run concurrently with in iduals from the same clutches. Here, we show that frogs from an evolutionarily long-exposed and phenotypically more resistant population of the highly susceptible alpine tree frog demonstrate a more robust innate and adaptive immune response at the critical early subclinical stage of infection when compared with two more susceptible populations. These results are consistent with the occurrence of evolution of resistance against chytridiomycosis, help to explain underlying resistance mechanisms, and provide genes of potential interest and sequence data for future research. We recommend further investigation of cell-mediated immunity pathways, the role of interferons and mechanisms of lymphocyte suppression.
Experimental infection of self-cured Leiopelma archeyi with the amphibian chytrid Batrachochytrium dendrobatidis
Publisher: Inter-Research Science Center
Date: 26-05-2010
DOI: 10.3354/DAO02227
Abstract: The susceptibility of Archey's frog Leiopelma archeyi to Batrachochytrium dendrobatidis (Bd) is unknown, although one large population is thought to have declined sharply due to chytridiomycosis. As primary infection experiments were not permitted in this endangered New Zealand species, 6 wild-caught L. archeyi that naturally cleared infections with Bd while in captivity were exposed again to Bd to assess their immunity. These frogs were from an infected population at Whareorino, which has no known declines. All 6 L. archeyi became reinfected at low intensities, but rapidly self cured, most by 2 wk. Six Litoria ewingii were used as positive controls and developed heavier infections and clinical signs by 3 wk, demonstrating that the zoospore inoculum was virulent. Six negative controls of each species remained uninfected and healthy. Our results show that L. archeyi that have self cured have resistance to chytridiomycosis when exposed. The pattern is consistent with innate or acquired immunity to Bd, and immunological studies are needed to confirm this.
Amphibians with infectious disease increase their reproductive effort: evidence for the terminal investment hypothesis
Publisher: The Royal Society
Date: 06-2016
DOI: 10.1098/RSOB.150251
Abstract: Mounting an immune response to fight disease is costly for an organism and can reduce investment in another life-history trait, such as reproduction. The terminal investment hypothesis predicts that an organism will increase reproductive effort when threatened by disease. The reproductive fitness of hibians infected with the deadly fungal pathogen Batrachochytrium dendrobatidis ( Bd ) is largely unknown. In this study, we explored gametogenesis in two endangered and susceptible frog species, Pseudophryne corroboree and Litoria verreauxii alpina. Gametogenesis, both oogenesis and spermatogenesis, increased when animals were experimentally infected with Bd . In P. corroboree , infected males have thicker germinal epithelium, and a larger proportion of spermatocytes. In L. v. alpina , infected males had more spermatic cell bundles in total, and a larger proportion of spermatozoa bundles. In female L. v. alpina , ovaries and oviducts were larger in infected animals, and there were more cells present within the ovaries. Terminal investment has consequences for the evolution of disease resistance in declining species. If infected animals are increasing reproductive efforts and producing more offspring before succumbing to disease, it is possible that population-level selection for disease resistance will be minimized.
Epidermal cell death in frogs with chytridiomycosis
Publisher: PeerJ
Date: 02-2017
DOI: 10.7717/PEERJ.2925
Abstract: Amphibians are declining at an alarming rate, and one of the major causes of decline is the infectious disease chytridiomycosis. Parasitic fungal sporangia occur within epidermal cells causing epidermal disruption, but these changes have not been well characterised. Apoptosis (planned cell death) can be a damaging response to the host but may alternatively be a mechanism of pathogen removal for some intracellular infections. In this study we experimentally infected two endangered hibian species Pseudophryne corroboree and Litoria verreauxii alpina with the causal agent of chytridiomycosis. We quantified cell death in the epidermis through two assays: terminal transferase-mediated dUTP nick end-labelling (TUNEL) and caspase 3/7. Cell death was positively associated with infection load and morbidity of clinically infected animals. In infected hibians, TUNEL positive cells were concentrated in epidermal layers, correlating to the localisation of infection within the skin. Caspase activity was stable and low in early infection, where pathogen loads were light but increasing. In animals that recovered from infection, caspase activity gradually returned to normal as the infection cleared. Whereas, in hibians that did not recover, caspase activity increased dramatically when infection loads peaked. Increased cell death may be a pathology of the fungal parasite, likely contributing to loss of skin homeostatic functions, but it is also possible that apoptosis suppression may be used initially by the pathogen to help establish infection. Further research should explore the specific mechanisms of cell death and more specifically apoptosis regulation during fungal infection.
Whether the Weather Drives Patterns of Endemic Amphibian Chytridiomycosis: A Pathogen Proliferation Approach
Publisher: Public Library of Science (PLoS)
Date: 17-04-2013
Experimental evolution alters the rate and temporal pattern of population growth in Batrachochytrium dendrobatidis, a lethal fungal pathogen of amphibians
Publisher: Wiley
Date: 09-2014
DOI: 10.1002/ECE3.1199
Dingoes (Canis dingo Meyer, 1793) continue to be an important reservoir host of Dirofilaria immitis in low density housing areas in Australia
Publisher: Elsevier BV
Date: 2016
CHLORAMPHENICOL WITH FLUID AND ELECTROLYTE THERAPY CURES TERMINALLY ILL GREEN TREE FROGS (LITORIA CAERULEA) WITH CHYTRIDIOMYCOSIS
Publisher: American Association of Zoo Veterinarians
Date: 06-2012
DOI: 10.1638/2011-0231.1
Abstract: Terminal changes in frogs infected with the hibian fungal pathogen Batrachochytrium dendrobatidis (Bd) include epidermal degeneration leading to inhibited epidermal electrolyte transport, systemic electrolyte disturbances, and asystolic cardiac arrest. There are few reports of successful treatment of chytridiomycosis and none that include curing hibians with severe disease. Three terminally ill green tree frogs (Litoria caerulea) with heavy Bd infections were cured using a combination of continuous shallow immersion in 20 mg/L chlor henicol solution for 14 days, parenteral isotonic electrolyte fluid therapy for 6 days, and increased ambient temperature to 28 degrees C for 14 days. All terminally ill frogs recovered rapidly to normal activity levels and appetite within 5 days of commencing treatment. In contrast, five untreated terminally ill L. caerulea with heavy Bd infections died within 24-48 hr of becoming moribund. Subclinical infections in 15 experimentally infected L. caerulea were cured within 28 days by continuous shallow immersion in 20 mg/L chlor henicol solution without adverse effects. This is the first known report of a clinical treatment protocol for curing terminally ill Bd-infected frogs.
A guide for ecologists: Detecting the role of disease in faunal declines and managing population recovery
Publisher: Elsevier BV
Date: 10-2017
Climatic suitability influences species specific abundance patterns of Australian flying foxes and risk of Hendra virus spillover
Publisher: Elsevier BV
Date: 12-2016
After the epidemic: Ongoing declines, stabilizations and recoveries in amphibians afflicted by chytridiomycosis
Publisher: Elsevier BV
Date: 02-2017
The epidemiology of melioidosis in the Balimo region of Papua New Guinea
Publisher: Cambridge University Press (CUP)
Date: 22-08-2007
DOI: 10.1017/S0950268807009429
Abstract: The distribution of Burkholderia pseudomallei was determined in soil collected from a rural district in Papua New Guinea (PNG) where melioidosis had recently been described, predominately affecting children. In 274 s les, 2·6% tested culture-positive for B. pseudomallei . Pulsed-field gel electrophoresis using Spe I digests and rapid polymorphic DNA PCR with five primers demonstrated a single clone amongst clinical isolates and isolates cultured from the environment that was commonly used by children from whom the clinical isolates were derived. We concluded that in iduals in this region most probably acquired the organism through close contact with the environment at these sites. Burkholderia thailandensis , a closely related Burkholderia sp. was isolated from 5·5% of s les tested, an observation similar to that of melioidosis-endemic areas in Thailand. This is the first report of an environmental reservoir for melioidosis in PNG and confirms the Balimo district in PNG as melioidosis endemic.
Serodiagnosis of Toxoplasmosis in a Common Wombat
Publisher: Wildlife Disease Association
Date: 04-1997
DOI: 10.7589/0090-3558-33.2.346
Abstract: An 8-yr-old captive, female common wombat (Vombatus ursinus) from Victoria, Australia was euthanased after an illness of 36 days manifested by lethargy, inappetance and terminal coma with respiratory failure. Toxoplasmosis was diagnosed during life by the Toxoplasma direct agglutination test (DAT) which showed a positive initial titre of 1:1,024 at 22 days after onset of illness and a four fold rise in titre to 1:4,098 2 wk later, just prior to death. The Toxoplasma modified agglutination test (MAT) remained negative over this time period. The serological diagnosis was confirmed by histological diagnosis of granulomatous encephalitis, focal myocarditis, interstitial pneumonia and severe adrenal cortical necrosis and the presence of tachyzoites of Toxoplasma gondii in large numbers within the focal necrotic lesions in the brain, myocardium and adrenal cortices. The serological response in the wombat differed from that of the typical eutherian which exhibits a reaction in both the DAT and MAT within 2 wk of infection with T. gondii. An incidental finding was calcification in the media of the ascending aorta and proximal parts of the major arteries.
Environmental Refuge from Disease-Driven Amphibian Extinction
Publisher: Wiley
Date: 08-09-2011
DOI: 10.1111/J.1523-1739.2011.01728.X
Abstract: Species that are tolerant of broad environmental gradients may be less vulnerable to epizootic outbreaks of disease. Chytridriomycosis, caused by the fungus Batrachochytrium dendrobatidis, has been linked to extirpations and extinctions of hibian species in many regions. The pathogen thrives in cool, moist environments, and high hibian mortality rates have commonly occurred during chytridiomycosis outbreaks in hibian populations in high-elevation tropical rainforests. In Australia several high-elevation species, including the armored mist frog (Litoria lorica), which is designated as critically endangered by the International Union for the Conservation of Nature (IUCN), were believed to have gone extinct during chytridiomycosis outbreaks in the 1980s and early 1990s. Species with greater elevational ranges disappeared from higher elevations, but remained common in the lowlands. In June 2008, we surveyed a stream in a high-elevation dry sclerophyll forest and discovered a previously unknown population of L. lorica and a population of the waterfall frog (Litoria nannotis). We conducted 6 additional surveys in June 2008, September 2008, March 2009, and August 2009. Prevalences of B. dendrobatidis infection (number infected per total s led) were consistently high in frogs (mean 82.5%, minimum 69%) of both species and in tadpoles (100%) during both winter (starting July) and summer (starting February). However, no in iduals of either species showed clinical signs of disease, and they remained abundant (3.25 - 8.75 in iduals of L. lorica and 6.5-12.5 in iduals of L. nannotis found erson/100 m over 13 months). The high-elevation dry sclerophyll site had little canopy cover, low annual precipitation, and a more defined dry season than a nearby rainforest site, where L. nannotis was more negatively affected by chytridiomycosis. We hypothesize this lack of canopy cover allowed the rocks on which frogs perched to warm up, thereby slowing growth and reproduction of the pathogen on the hosts. In addition, we suggest surveys for apparently extinct or rare species should not be limited to core environments.
First Evidence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Hong Kong Amphibian Trade
Publisher: Public Library of Science (PLoS)
Date: 05-03-2014
Treatment of chytridiomycosis requires urgent clinical trials
Publisher: Inter-Research Science Center
Date: 23-09-2010
DOI: 10.3354/DAO02238
Abstract: Effective and safe treatments of hibian chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd), are needed to prevent mortality in captive programs, reduce the risk of disease spread, and better manage the disease in threatened wild populations. Bd is susceptible to a range of antifungal agents and low levels of heat (>30 degrees C) when tested in vitro, but there are few proven methods for clearing adult hibians of Bd, and acute drug toxicity is a problem for tadpoles and juveniles. In postmetamorphic animals, heat (32 and 37 degrees C) is the only well-supported treatment. Antifungal drugs have not undergone rigorous testing--for ex le, trials were small or lacked controls and thorough post-treatment testing. In addition, pharmacokinetic studies have not been performed so there are no data on blood or tissue levels of antifungal agents. However, itraconazole baths have been widely used in hibian rescue and conservation programs and anecdotal evidence suggests that they are effective for adults and subadults. In an experimental trial with tadpoles, a low dose of itraconazole cleared Bd but may have been associated with cutaneous depigmentation. Fluconazole appeared safe for tadpoles as it did not cause mortality, and future attempts to find an effective dose may be worthwhile. Palliative restoration of blood sodium and potassium levels by administration of electrolyte solutions appears useful in frogs with clinical chytridiomycosis. Randomised and blinded clinical trials, which include basic pharmacological studies, are urgently needed to provide comparable evidence for the safety and efficacy of treatment options which are likely to vary with hibian species. Priorities are to validate and optimize the use of heat and itraconazole regimes.
Presence of amphibian chytrid fungus (Batrachochytrium dendrobatidis) in rainwater suggests aerial dispersal is possible
Publisher: Springer Science and Business Media LLC
Date: 17-03-2015
Priorities for management of chytridiomycosis in Australia: Saving frogs from extinction
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/WR15071
Abstract: To protect Australian hibian bio ersity, we have identified and prioritised frog species at an imminent risk of extinction from chytridiomycosis, and devised national management and research priorities for disease mitigation. Six Australian frogs have not been observed in the wild since the initial emergence of chytridiomycosis and may be extinct. Seven extant frog species were assessed as needing urgent conservation interventions because of (1) their small populations and/or ongoing declines throughout their ranges (southern corroboree frog (Pseudophryne corroboree, New South Wales), northern corroboree frog (Pseudophryne pengilleyi, Australian Capital Territory, New South Wales), Baw Baw frog (Philoria frosti, Victoria), Litoria spenceri (spotted tree frog, Victoria, New South Wales), Kroombit tinkerfrog (Taudactylus pleione, Queensland), armoured mist frog (Litoria lorica, Queensland)) or (2) predicted severe decline associated with the spread of chytridiomycosis in the case of Tasmanian tree frog (Litoria burrowsae, Tasmania). For these species, the risk of extinction is high, but can be mitigated. They require increased survey effort to define their distributional limits and to monitor and detect further population changes, as well as well-resourced management strategies that include captive assurance populations. A further 22 frog species were considered at a moderate to lower risk of extinction from chytridiomycosis. Management actions that identify and create or maintain habitat refugia from chytridiomycosis and target other threatening processes such as habitat loss and degradation may be effective in promoting their recovery. Our assessments for some of these species remain uncertain and further taxonomical clarification is needed to determine their conservation importance. Management actions are currently being developed and trialled to mitigate the threat posed by chytridiomycosis. However, proven solutions to facilitate population recovery in the wild are lacking hence, we prioritise research topics to achieve this aim. Importantly, the effectiveness of novel management solutions will likely differ among species due to variation in disease ecology, highlighting the need for species-specific research. We call for an independent management and research fund of AU$15 million over 5 years to be allocated to recovery actions as determined by a National Chytridiomycosis Working Group of hibian managers and scientists. Procrastination on this issue will likely result in additional extinction of Australia’s hibians in the near future.
Hematologic and plasma biochemical reference intervals for health monitoring of wild Australian tree frogs
Publisher: Wiley
Date: 24-09-2012
Causes of Morbidity and Mortality of Wild Aquatic Birds at Billabong Sanctuary, Townsville, North Queensland, Australia
Publisher: American Association of Avian Pathologists (AAAP)
Date: 03-2012
Investigating community disease dynamics can lead to more effective conservation efforts
Publisher: Wiley
Date: 04-2018
DOI: 10.1111/ACV.12416
Pathogenesis of chytridiomycosis, a cause of catastrophic amphibian declines
Publisher: American Association for the Advancement of Science (AAAS)
Date: 23-10-2009
Abstract: The global hibian decline has been attributed, among other causes, to an hibian skin disease chytridiomycosis caused by the fungus Batrachochytrium dendrobatidis . However, how this pathogen causes mortality has been unclear. Voyles et al. (p. 582 ) show that this superficial skin infection may lead to cardiac failure owing to changes caused by lowered ion transport through the skin and consequent electrolyte reduction in the blood.
Dose-dependent morbidity of freshwater turtle hatchlings, Emydura macquarii krefftii, inoculated with Ranavirus isolate (Bohle iridovirus, Iridoviridae)
Publisher: Microbiology Society
Date: 10-2019
DOI: 10.1099/JGV.0.001324
Abstract: Ranaviral infections cause mass die-offs in wild and captive turtle populations. Two experimental studies were performed to first determine the susceptibility of an Australian turtle species ( Emydura macquarii krefftii ) to different routes of infection and second examine the effect of viral titre on the morbidity in hatchlings. All inoculation routes (intracoelomic, intramuscular and oral) produced disease, but the clinical signs, histopathology and time to onset of disease varied with the route. The median infectious and lethal doses for intramuscularly inoculated hatchlings were 10 2 . 52 (1.98–2.93) and 10 4.43 (3.81–5.19) TCID 50 ml −1 , respectively. Clinical signs began 14 to 29 days post-inoculation and the median survival time was 22 days (16–25) across all dose groups. For every 10-fold increase in dose, the odds of developing any clinical signs or severe clinical signs increased by 3.39 [ P .01, 95 % confidence interval (CI): 1.81–6.36] and 3.71 ( P .01, 95 % CI: 1.76–7.80), respectively. Skin lesions, previously only reported in ranaviral infection in lizards, were observed in the majority of intramuscularly inoculated hatchlings that developed ranaviral disease. The histological changes were consistent with those in previous reports for reptiles and consisted of necrosis at or near the site of injection, in the spleen, liver and oral cavity. Systemic inflammation was also observed, predominantly affecting necrotic organs. The estimates reported here can be used to model ranaviral disease and quantify and manage at-risk populations.
Electrolyte depletion and osmotic imbalance in amphibians with chytridiomycosis
Publisher: Inter-Research Science Center
Date: 14-09-2007
DOI: 10.3354/DAO01838
Abstract: Mounting evidence implicates the disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis, in global hibian declines and extinctions. While the virulence of this disease has been clearly demonstrated, there is, as yet, no mechanistic explanation for how B. dendrobatidis kills hibians. To investigate the pathology of chytridiomycosis, blood s les were collected from uninfected, aclinically infected and clinically diseased hibians and analyzed for a wide range of biochemical and hematological parameters. Here, we show that green tree frogs Litoria caerulea with severe chytridiomycosis had reduced plasma osmolality, sodium, potassium, magnesium and chloride concentrations. Stable plasma albumin, hematocrit and urea levels indicated that hydration status was unaffected, signifying depletion of electrolytes from circulation rather than dilution due to increased water uptake. We suggest that B. dendrobatidis kills hibians by disrupting normal epidermal functioning, leading to osmotic imbalance through loss of electrolytes. Determining how B. dendrobatidis kills hibians is fundamental to understanding the host-pathogen relationship and thus the population declines attributed to B. dendrobatidis. Understanding the mechanisms of mortality may also explain interspecific variation in susceptibility to chytridiomycosis.
Review of the Amphibian Immune Response to Chytridiomycosis, and Future Directions
Publisher: Frontiers Media SA
Date: 09-11-2018
Development and worldwide use of a non-lethal and minimal population-level impact protocols for the isolation of chytrids from amphibians
Publisher: Cold Spring Harbor Laboratory
Date: 11-01-2018
DOI: 10.1101/246538
Abstract: Parasitic chytrid fungi have emerged as a significant threat to hibian species worldwide, necessitating the development of techniques to isolate these pathogens into sterile culture for research purposes. However, early methods of isolating chytrids from their hosts relied on killing hibians. We modified a pre-existing protocol for isolating chytrids from infected animals to use toe clips and biopsies from toe webbing rather than euthanizing hosts, and distributed the protocol to interested researchers worldwide as part of the Bio ERsA project RACE – here called the RML protocol. In tandem, we developed a lethal procedure for isolating chytrids from tadpole mouthparts. Reviewing a database of use a decade after their inception, we find that these methods have been widely applied across at least 5 continents, 23 countries and in 62 hibian species, and have been successfully used to isolate chytrids in remote field locations. Isolation of chytrids by the non-lethal RML protocol occured in 18% of attempts with 207 fungal isolates and three species of chytrid being recovered. Isolation of chytrids from tadpoles occured in 43% of attempts with 334 fungal isolates of one species ( Batrachochytrium dendrobatidis ) being recovered. Together, these methods have resulted in a significant reduction and refinement of our use of threatened hibian species and have improved our ability to work with this important group of emerging fungal pathogens.
Validation of Diagnostic Tests in Wildlife: The Case of Chytridiomycosis in Wild Amphibians
Publisher: Society for the Study of Amphibians and Reptiles
Date: 12-2011
DOI: 10.1670/10-193.1
Susceptibility of frogs to chytridiomycosis correlates with increased levels of immunomodulatory serotonin in the skin
Publisher: Hindawi Limited
Date: 13-08-2019
DOI: 10.1111/CMI.13089
Abstract: Chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a skin disease responsible for the global decline of hibians. Frog species and populations can vary in susceptibility, but this phenomenon remains poorly understood. Here, we investigated serotonin in the skin of infected and uninfected frogs. In more susceptible frog populations, skin serotonin rose with increasing infection intensity, but decreased in later stages of the disease. The more resistant population maintained a basal level of skin serotonin. Serotonin inhibited both Bd sporangial growth and Jurkat lymphocyte proliferation in vitro. However, serotonin accumulates in skin granular glands, and this compartmentalisation may prevent inhibition of Bd growth in vivo. We suggest that skin serotonin increases in susceptible frogs due to pathogen excretion of precursor tryptophan, but that resistant frogs are able to control the levels of serotonin. Overall, the immunosuppressive effects of serotonin may contribute to the susceptibility of frogs to chytridiomycosis.
A zoospore inhibition technique to evaluate the activity of antifungal compounds against Batrachochytrium dendrobatidis and unsuccessful treatment of experimentally infected green tree frogs (Litoria
Publisher: Elsevier BV
Date: 08-2009
DOI: 10.1016/J.RVSC.2008.11.005
Abstract: Effective and safe treatments of chytridiomycosis in hibians, caused by Batrachochytrium dendrobatidis, are needed to help prevent mortality in captive programs for threatened species, to reduce the risk of spread, and to better manage the disease in threatened populations. We describe a simple method to determine minimum inhibitory concentrations (MICs) of antifungal agents that involves adding zoospores to various drug concentrations in 96 well plates and microscopic observation after four days. We report results from testing 10 commercially available antifungal compounds: benzalkonium chloride (<0.78 microg/ml), povidone iodine (312.5 microg/ml), hotericin B (3.125 microg/ml), fluconazole (<1.56 microg/ml), itraconazole (<1.56 microg/ml), enilconazole (<1.56 microg/ml), mercurochrome (6.25 microg/ml), sodium chloride (12.5mg/ml), methylene blue (<1.56 microg/ml) and Virkon (3.125 microg/ml). For treatment trials of juvenile Litoria caerulea, baths of benzalkonium chloride at 1mg/L and fluconazole at 25mg/L were used on 18 experimentally infected frogs per treatment. Although these treatments resulted in longer survival times (mean 43.7+/-11.3 days) than in the untreated controls (37.9+/-9.3 days), the mortality rate was still 100%. Higher doses of fluconazole are suggested for further animal trials.
Island of opportunity: can New Guinea protect amphibians from a globally emerging pathogen?
Publisher: Wiley
Date: 03-06-2019
DOI: 10.1002/FEE.2057
The efficacy and pharmacokinetics of terbinafine against the frog-killing fungus (Batrachochytrium dendrobatidis)
Publisher: Oxford University Press (OUP)
Date: 16-03-2018
DOI: 10.1093/MMY/MYY010
Abstract: Captive and wild hibians are under threat of extinction from the deadly fungal pathogen Batrachochytrium dendrobatidis (Bd). The antifungal drug terbinafine (TBF) is used by pet owners to treat Bd-infected frogs however, it is not widely used in academic or zoological institutions due to limited veterinary clinical trials. To assess TBF's efficacy, we undertook treatment trials and pharmacokinetic studies to investigate drug absorption and persistence in frog skin and then we correlated these data to the minimal lethal concentrations (MLC) against Bd. Despite an initial reduction in zoospore load, the recommended treatment (five daily 5 min 0.01% TBF baths) was unable to cure experimentally infected alpine tree frogs and naturally infected common eastern froglets. In vitro and in vivo pharmacokinetics showed that absorbed TBF accumulates in frog skin with increased exposure, indicating its suitability for treating cutaneous pathogens via direct application. The MLC of TBF for zoosporangia was 100 μg/ml for 2 h, while the minimal inhibitory concentration was 2 μg/ml, suggesting that the drug concentration absorbed during 5 min treatments is not sufficient to cure high Bd burdens. With longer treatments of five daily 30 min baths, Bd clearance improved from 12.5% to 50%. A higher dose of 0.02% TBF resulted in 78% of animals cured however, clearance was not achieved in all in iduals due to low TBF skin persistence, as the half-life was less than 2 h. Therefore, the current TBF regime is not recommended as a universal treatment against Bd until protocols are optimized, such as with increased exposure frequency.
Avian influenza in Australia: a summary of 5 years of wild bird surveillance
Publisher: Wiley
Date: 26-10-2015
DOI: 10.1111/AVJ.12379
Abstract: Avian influenza viruses (AIVs) are found worldwide in numerous bird species, causing significant disease in gallinaceous poultry and occasionally other species. Surveillance of wild bird reservoirs provides an opportunity to add to the understanding of the epidemiology of AIVs. This study examined key findings from the National Avian Influenza Wild Bird Surveillance Program over a 5-year period (July 2007-June 2012), the main source of information on AIVs circulating in Australia. The overall proportion of birds that tested positive for influenza A via PCR was 1.9 ± 0.1%, with evidence of widespread exposure of Australian wild birds to most low pathogenic avian influenza (LPAI) subtypes (H1-13, H16). LPAI H5 subtypes were found to be dominant and widespread during this 5-year period. Given Australia's isolation, both geographically and ecologically, it is important for Australia not to assume that the epidemiology of AIV from other geographic regions applies here. Despite all previous highly pathogenic avian influenza outbreaks in Australian poultry being attributed to H7 subtypes, widespread detection of H5 subtypes in wild birds may represent an ongoing risk to the Australian poultry industry.
Non‐declining amphibians can be important reservoir hosts for amphibian chytrid fungus
Publisher: Wiley
Date: 13-11-2017
DOI: 10.1111/ACV.12380
Surveillance for Emerging Biodiversity Diseases of Wildlife
Publisher: Public Library of Science (PLoS)
Date: 29-05-2014
Letter to the editor: Comment on chytrid Batrachochytrium dendrobatidis fungal infection in freshwater prawn, Macrobrachium rosenbergii (de Man)-a new report
Publisher: Elsevier BV
Date: 02-2017
Climate Change Could Increase the Geographic Extent of Hendra Virus Spillover Risk
Publisher: Springer Science and Business Media LLC
Date: 19-03-2018
Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity
Publisher: American Association for the Advancement of Science (AAAS)
Date: 29-03-2019
Abstract: Rapid spread of disease is a hazard in our interconnected world. The chytrid fungus Batrachochytrium dendrobatidis was identified in hibian populations about 20 years ago and has caused death and species extinction at a global scale. Scheele et al. found that the fungus has caused declines in hibian populations everywhere except at its origin in Asia (see the Perspective by Greenberg and Palen). A majority of species and populations are still experiencing decline, but there is evidence of limited recovery in some species. The analysis also suggests some conditions that predict resilience. Science , this issue p. 1459 see also p. 1386
In Memory of Rick Speare
Publisher: Springer Science and Business Media LLC
Date: 18-08-2016
Temperature alters reproductive life history patterns in Batrachochytrium dendrobatidis, a lethal pathogen associated with the global loss of amphibians
Publisher: Wiley
Date: 04-08-2012
DOI: 10.1002/ECE3.334
Impact and Dynamics of Disease in Species Threatened by the Amphibian Chytrid Fungus, Batrachochytrium dendrobatidis
Publisher: Wiley
Date: 14-09-2009
DOI: 10.1111/J.1523-1739.2009.01211.X
Abstract: Estimating disease-associated mortality and transmission processes is difficult in free-ranging wildlife but important for understanding disease impacts and dynamics and for informing management decisions. In a capture-mark-recapture study, we used a PCR-based diagnostic test in combination with multistate models to provide the first estimates of disease-associated mortality and detection, infection, and recovery rates for frogs endemically infected with the chytrid fungus Batrachochytrium dendrobatidis (Bd), which causes the pandemic hibian disease chytridiomycosis. We found that endemic chytridiomycosis was associated with a substantial reduction (approximately 38%) in apparent monthly survival of the threatened rainforest treefrog Litoria pearsoniana despite a long period of coexistence (approximately 30 years) detection rate was not influenced by disease status improved recovery and reduced infection rates correlated with decreased prevalence, which occurred when temperatures increased and incorporating changes in in iduals' infection status through time with multistate models increased effect size and support (98.6% vs. 71% of total support) for the presence of disease-associated mortality when compared with a Cormack-Jolly-Seber model in which infection status was restricted to the time of first capture. Our results indicate that hibian populations can face significant ongoing pressure from chytridiomycosis long after epidemics associated with initial Bd invasions subside, an important consideration for the long-term conservation of many hibian species worldwide. Our findings also improve confidence in estimates of disease prevalence in wild hibians and provide a general framework for estimating parameters in epidemiological models for chytridiomycosis, an important step toward better understanding and management of this disease.
More bark than bite: Comparative studies are needed to determine the importance of canine zoonoses in Aboriginal communities. A critical review of published research
Publisher: Wiley
Date: 25-03-2017
DOI: 10.1111/ZPH.12354
Validation of a geographic information system model for mapping the risk of fasciolosis in cattle and buffaloes in Cambodia
Publisher: Elsevier BV
Date: 02-2007
DOI: 10.1016/J.VETPAR.2006.08.033
Abstract: Maps showing gradations of risk of fasciolosis due to Fasciola gigantica in Cambodia were produced using geographic information systems (GIS) technology in conjunction with determinants of fasciolosis. A comparison between levels of risk predicted by the maps and field measurements of prevalence in 11 provinces (n=1406) showed general agreement, which suggested the epidemiological determinants and weightings used to produce the maps were appropriate. However, due to logistical constraints, prevalence was measured at the provincial level and animals were not randomly s led (and thus were unlikely to be representative of variability within provinces). To address this, additional field work was carried out to measure prevalence in more detail--faecal s les were collected from a randomly selected set of animals in four districts across a representative province for areas predicted to be at high risk (n=311), moderate risk (n=268) and no risk (n=262). As with the original field survey, the results show general agreement between prevalence and risk predicted by the maps, with the best fit found for areas predicted to be at high risk.
The Amphibian Chytrid Batrachochytrium dendrobatidis Occurs on Freshwater Shrimp in Rain Forest Streams in Northern Queensland, Australia
Publisher: Springer Science and Business Media LLC
Date: 04-01-2006
A survey of gastro-intestinal parasitic infection in domestic and wild birds in Chittagong and Greater Sylhet, Bangladesh
Publisher: Elsevier BV
Date: 11-2014
DOI: 10.1016/J.PREVETMED.2014.07.012
Abstract: A survey of gastrointestinal parasitic infection as determined by faecal examination was conducted among domestic and wild birds in Bangladesh. Birds were s led from households, wet markets and wetlands in Chittagong and Greater Sylhet districts during April 2012 to February 2013. Mist nets were used to catch resident wild and migratory birds. The overall prevalence of parasitic infection ranged among locations from 25 to 55% in indigenous domestic ducks (live bird s les=304), 20% in resident wild birds (environmental faecal s les=40) and 40% in migratory birds (live bird s les=35). The prevalence of parasitic infection was significantly higher in indigenous domestic ducks collected during summer (39%) than winter (22%) (p=0.04). In domestic indigenous ducks and Muscovy ducks, both single and multiple types of parasitic infections were found. However, other domestic birds and wild birds often had a single type of parasitic infection. Ascaridia spp. with an average egg load of 50-900, was commonly detected in faecal s les of domestic and wild birds in this study. Other identified parasites were Capillaria spp. and Heterakis spp. both in domestic and wild birds. Improvement of biosecurity measures for household duck farms through educating and motivating household farmers could help mitigate the effects of parasitic infection on production.
Chytridiomycosis and Seasonal Mortality of Tropical Stream‐Associated Frogs 15 Years after Introduction of Batrachochytrium dendrobatidis
Publisher: Wiley
Date: 16-05-2013
DOI: 10.1111/COBI.12073
Abstract: Assessing the effects of diseases on wildlife populations can be difficult in the absence of observed mortalities, but it is crucial for threat assessment and conservation. We performed an intensive capture-mark-recapture study across seasons and years to investigate the effect of chytridiomycosis on demographics in 2 populations of the threatened common mist frog (Litoria rheocola) in the lowland wet tropics of Queensland, Australia. Infection prevalence was the best predictor for apparent survival probability in adult males and varied widely with season (0-65%). Infection prevalence was highest in winter months when monthly survival probabilities were low (approximately 70%). Populations at both sites exhibited very low annual survival probabilities (12-15%) but high recruitment (71-91%), which resulted in population growth rates that fluctuated seasonally. Our results suggest that even in the absence of observed mortalities and continued declines, and despite host-pathogen co-existence for multiple host generations over almost 2 decades, chytridiomycosis continues to have substantial seasonally fluctuating population-level effects on hibian survival, which necessitates increased recruitment for population persistence. Similarly infected populations may thus be under continued threat from chytridiomycosis which may render them vulnerable to other threatening processes, particularly those affecting recruitment success.
Importance of health assessments for conservation in noncaptive wildlife
Publisher: Wiley
Date: 11-05-2022
DOI: 10.1111/COBI.13724
Abstract: Wildlife health assessments help identify populations at risk of starvation, disease, and decline from anthropogenic impacts on natural habitats. We conducted an overview of available health assessment studies in noncaptive vertebrates and devised a framework to strategically integrate health assessments in population monitoring. Using a systematic approach, we performed a thorough assessment of studies examining multiple health parameters of noncaptive vertebrate species from 1982 to 2020 ( n = 261 studies). We quantified trends in study design and diagnostic methods across taxa with generalized linear models, bibliometric analyses, and visual representations of study location versus bio ersity hotspots. Only 35% of studies involved international or cross‐border collaboration. Countries with both high and threatened bio ersity were greatly underrepresented. Species that were not listed as threatened on the International Union for Conservation of Nature Red List represented 49% of assessed species, a trend likely associated with the regional focus of most studies. We strongly suggest following wildlife health assessment protocols when planning a study and using statistically adequate s le sizes for studies establishing reference ranges. Across all taxa blood analysis (89%), body composition assessments (81%), physical examination (72%), and fecal analyses (24% of studies) were the most common methods. A conceptual framework to improve design and standardize wildlife health assessments includes guidelines on the experimental design, data acquisition and analysis, and species conservation planning and management implications. Integrating a physiological and ecological understanding of species resilience toward threatening processes will enable informed decision making regarding the conservation of threatened species.
Naïve rainforest frogs on Cape York, Australia, are at risk of the introduction of amphibian chytridiomycosis disease
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/ZO18041
Abstract: Amphibian chytridiomycosis disease has caused widespread declines and extinctions of frogs in cool, wet habitats in eastern Australia. Screening suggests that the disease does not yet occupy all areas modelled to be environmentally suitable, including rainforests on Cape York Peninsula. Cape Melville is an area of rainforest with several endemic frogs, including the stream-associated Melville Range treefrog (Litoria andiirrmalin), which is deemed at particular risk of disease impacts. We tested 40 L. andiirrmalin for chytrid infection by PCR and found them all to be negative. In conjunction with previous testing at another high-risk location, McIlwraith Range, this suggests that endemic rainforest frogs on Cape York have been spared the introduction of chytridiomycosis. We discuss how the disease could get to these areas, what can be done to reduce the risk, and suggest an emergency procedure should it be introduced.
Integrating species traits with extrinsic threats: closing the gap between predicting and preventing species declines
Publisher: The Royal Society
Date: 27-10-2010
Abstract: In studies of extinction risk, it is often insufficient to conclude that species with narrow ranges or small clutch sizes require prioritized protection. To improve conservation outcomes, we also need to know which threats interact with these traits to endanger some species but not others. In this study, we integrated the spatial patterns of key threats to Australian hibians with species' ecological/life-history traits to both predict declining species and identify their likely threats. In addition to confirming the importance of previously identified traits (e.g. narrow range size), we find that extrinsic threats (primarily the disease chytridiomycosis and invasive mosquitofish) are equally important and interact with intrinsic traits (primarily ecological group) to create guild-specific pathways to decline in our model system. Integrating the spatial patterns of extrinsic threats in extinction risk analyses will improve our ability to detect and manage endangered species in the future, particularly where data deficiency is a problem.
Using community surveillance data to differentiate between emerging and endemic amphibian diseases
Publisher: Inter-Research Science Center
Date: 17-02-2012
DOI: 10.3354/DAO02416
Abstract: We analyzed submission data from a wildlife care group during hibian disease surveillance in Queensland, Australia. Between January 1999 and December 2004, 877 white-lipped tree frogs Litoria infrafrenata were classified according to origin, season and presenting category. At least 69% originated from urban Cairns, significantly more than from rural and remote areas. Total submissions increased during the early and late dry seasons compared with the early wet season. Frogs most commonly presented each year with injury, followed by 'other', sparganosis and irreversible emaciation of unknown aetiology. This is the first report of Spirometra erinacei infection in this species. A high prevalence (28%) of visible S. erinacei infection was found in emaciated frogs, but this was not statistically different from that in non-emaciated diseased frogs (25%). However, 14 emaciated specimens that were necropsied all had heavy S. erinacei infections, and the odds of visible sparganosis were statistically greater in emaciated frogs compared with injured, non-diseased frogs. We provide a detailed case definition for a new endemic disease manifesting as irreversible emaciation, for which S. erinacei may be the primary aetiological agent. The lack of significant spatial or temporal patterns in case presentation suggests that this is not a currently emerging disease. We show that community wildlife groups can play a valuable role in monitoring disease trends, particularly in urban areas, but identify a number of limitations associated with passive syndromic surveillance. We conclude that it is critical that professionals be involved in establishing syndromic case definitions, diagnostic pathology, complementary active disease surveillance, and data analysis and interpretation in all wildlife disease investigations.
Low impact of chytridiomycosis on frog recruitment enables persistence in refuges despite high adult mortality
Publisher: Elsevier BV
Date: 02-2015
Toxic effects of mebendazole at high dose on the haematology of red-legged pademelons (Thylogale stigmatica)
Publisher: Wiley
Date: 05-2004
DOI: 10.1111/J.1751-0813.2004.TB12710.X
Abstract: To investigate the effects of mebendazole at high dose on the haematology of macropods. Experimental. Five red-legged pademelons (Thylogale stigmatica) were dosed orally with mebendazole at 50 mg/kg/d for 5 to 6 days. Two control pademelons were dosed with water. Regular blood s les were taken for haematology over 20 days. All four treated pademelons s led at 5 days developed severe leucopenia and neutropenia, moderate lymphopenia, thrombocytopenia, eosinopenia and monocytopenia, as well as bone marrow aplasia within 5 to 11 days after the first mebendazole dose. Four pademelons died unexpectedly or became ill and were euthanased 5 to 11 days after the first dose while the other animal recovered after 5 days of illness. Necropsy revealed systemic infection with opportunistic enteric bacteria, non-suppurative inflammation in tissues, haemorrhage and ulceration of the gastrointestinal tract. Red-legged pademelons rapidly develop bone-marrow aplasia and subsequent septicaemia after administration of high doses of mebendazole. Mebendazole at high doses should not be used for macropods.
In vitro sensitivity of the amphibian pathogen Batrachochytrium dendrobatidis to antifungal therapeutics
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.RVSC.2014.06.013
Abstract: Chytridiomycosis, a skin disease caused by Batrachochytrium dendrobatidis, has caused hibian declines worldwide. Amphibians can be treated by percutaneous application of antimicrobials, but knowledge of in vitro susceptibility is lacking. Using a modified broth microdilution method, we describe the in vitro sensitivity of two Australian isolates of B. dendrobatidis to six antimicrobial agents. Growth inhibition was observed, by measurement of optical density, with all agents. Minimum inhibitory concentrations (µg/ml isolate 1/2) were - voriconazole 0.016/0.008 itraconazole 0.032/0.016 terbinafine 0.063/0.063 fluconazole 0.31/0.31 chlor henicol 12.5/12.5 hotericin B 12.5/6.25. Killing effects on zoospores were assessed by observing motility. Amphotericin B and terbinafine killed zoospores within 5 and 30 min depending on concentration, but other antimicrobials were not effective at the highest concentrations tested (100 µg/ml). This knowledge will help in drug selection and treatment optimization. As terbinafine was potent and has rapid effects, study of its pharmacokinetics, safety and efficacy is recommended.
Conservation and health of Lumholtz’s tree-kangaroo (Dendrolagus lumholtzi)
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AM17030
Abstract: Lumholtz’s tree-kangaroo (Dendrolagus lumholtzi) is an iconic species in far north Queensland yet little is known about its health or population status. Studies on this species have been conducted in a limited number of locations and focused primarily on ecology, habitat use and home-range size. The species is relatively common in the Atherton Tablelands but habitat loss, predation by domestic, feral and wild dogs, vehicle strike, low fecundity, and disease have been identified as threats to the population. We review knowledge of population ecology and threats for this species, and include a novel collation of disease reports on all tree-kangaroos with particular reference to Lumholtz’s tree-kangaroo. Health of Lumholtz’s tree-kangaroo appears to be impacted by the increase in humans and domestic animals in their range. There have been reports of melioidosis, toxoplasmosis, tick paralysis and blindness in wild tree-kangaroos. We identify where increased information on health and population viability will improve conservation and management of the species.
Effects of chytridiomycosis on hematopoietic tissue in the spleen, kidney and bone marrow in three diverse amphibian species
Publisher: Oxford University Press (OUP)
Date: 14-07-2016
Abstract: One of the major causes of hibian population decline is the deadly fungal pathogen Batrachochytrium dendrobatidis, Bd Research on pathogenesis and host immunity aims to inform development of targeted conservation interventions. Studies examining global host immune responses as well as effects on lymphocytes in vitro suggest that Bd infection causes immunosuppression. However, it is unknown which hematopoietic tissues are affected and if these effects differ among host species. We investigated the effect of experimental Bd infection on three erse hibian species by quantifying the amount of hematopoietic tissue in the spleen, bone marrow and kidney. Upon Bd infection, hematopoietic tissue in the kidney tended to be depleted, while the spleen appeared unaffected. The bone marrow in highly susceptible species was depleted, whereas an increase in hematopoietic tissue was observed in the more resistant species. Our study demonstrates that species and hematopoietic tissues behave differently in response to Bd infection, and may be related to the species' susceptibility to infection.
Chytridiomycosis causes catastrophic organism-wide metabolic dysregulation including profound failure of cellular energy pathways
Publisher: Springer Science and Business Media LLC
Date: 29-05-2018
DOI: 10.1038/S41598-018-26427-Z
Abstract: Chytridiomycosis is among several recently emerged fungal diseases of wildlife that have caused decline or extinction of naïve populations. Despite recent advances in understanding pathogenesis, host response to infection remains poorly understood. Here we modelled a total of 162 metabolites across skin and liver tissues of 61 frogs from four populations (three long-exposed and one naïve to the fungus) of the Australian alpine tree frog ( Litoria verreauxii alpina ) throughout a longitudinal exposure experiment involving both infected and negative control in iduals. We found that chytridiomycosis dramatically altered the organism-wide metabolism of clinically diseased frogs. Chytridiomycosis caused catastrophic failure of normal homeostatic mechanisms (interruption of biosynthetic and degradation metabolic pathways), and pronounced dysregulation of cellular energy metabolism. Key intermediates of the tricarboxylic acid cycle were markedly depleted, including in particular α-ketoglutarate and glutamate that together constitute a key nutrient pathway for immune processes. This study was the first to apply a non-targeted metabolomics approach to a fungal wildlife disease and specifically to dissect the host-pathogen interface of Bd-infected frogs. The patterns of metabolite accumulation we have identified reveal whole-body metabolic dysfunction induced by a fungal skin infection, and these findings have broad relevance for other fungal diseases.
Prior Infection Does Not Improve Survival against the Amphibian Disease Chytridiomycosis
Publisher: Public Library of Science (PLoS)
Date: 22-02-2013
The hookworm Ancylostoma ceylanicum : An emerging public health risk in Australian tropical rainforests and Indigenous communities
Publisher: Elsevier BV
Date: 06-2017
Microclimates Might Limit Indirect Spillover of the Bat Borne Zoonotic Hendra Virus
Publisher: Springer Science and Business Media LLC
Date: 14-01-2017
Interventions for Reducing Extinction Risk in Chytridiomycosis-Threatened Amphibians
Publisher: Wiley
Date: 27-06-2014
DOI: 10.1111/COBI.12322
Abstract: Wildlife diseases pose an increasing threat to bio ersity and are a major management challenge. A striking ex le of this threat is the emergence of chytridiomycosis. Despite diagnosis of chytridiomycosis as an important driver of global hibian declines 15 years ago, researchers have yet to devise effective large-scale management responses other than biosecurity measures to mitigate disease spread and the establishment of disease-free captive assurance colonies prior to or during disease outbreaks. We examined the development of management actions that can be implemented after an epidemic in surviving populations. We developed a conceptual framework with clear interventions to guide experimental management and applied research so that further extinctions of hibian species threatened by chytridiomycosis might be prevented. Within our framework, there are 2 management approaches: reducing Batrachochytrium dendrobatidis (the fungus that causes chytridiomycosis) in the environment or on hibians and increasing the capacity of populations to persist despite increased mortality from disease. The latter approach emphasizes that mitigation does not necessarily need to focus on reducing disease-associated mortality. We propose promising management actions that can be implemented and tested based on current knowledge and that include habitat manipulation, antifungal treatments, animal translocation, bioaugmentation, head starting, and selection for resistance. Case studies where these strategies are being implemented will demonstrate their potential to save critically endangered species.
BASELINE CUTANEOUS BACTERIA OF FREE-LIVING NEW ZEALAND NATIVE FROGS (LEIOPELMA ARCHEYIANDLEIOPELMA HOCHSTETTERI) AND IMPLICATIONS FOR THEIR ROLE IN DEFENSE AGAINST THE AMPHIBIAN CHYTRID
Publisher: Wildlife Disease Association
Date: 10-2014
DOI: 10.7589/2013-07-186
Abstract: Abstract Knowledge of baseline cutaneous bacterial microbiota may be useful in interpreting diagnostic cultures from captive sick frogs and as part of quarantine or pretranslocation disease screening. Bacteria may also be an important part of innate immunity against chytridiomycosis, a fungal skin disease caused by Batrachochytrium dendrobatidis (Bd). In February 2009, 92 distinct bacterial isolates from the ventral skin of 64 apparently healthy Leiopelma archeyi and Leiopelma hochstetteri native frogs from the Coromandel and Whareorino regions in New Zealand were identified using molecular techniques. The most-common isolates identified in L. archeyi were Pseudomonas spp. and the most common in L. hochstetteri were Flavobacterium spp. To investigate the possible role of bacteria in innate immunity, a New Zealand strain of Bd (Kaikorai Valley-Lewingii-2008-SDS1) was isolated and used in an in vitro challenge assay to test for inhibition by bacteria. One bacterial isolate, a Flavobacterium sp., inhibited growth of Bd. These results imply that erse cutaneous bacteria are present and may play a role in the innate defense in Leiopelma against pathogens, including Bd, and are a starting point for further investigation.
Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Wild Amphibian Populations in Madagascar
Publisher: Public Library of Science (PLoS)
Date: 17-06-2015
FLUOROSIS AS A PROBABLE FACTOR IN METABOLIC BONE DISEASE IN CAPTIVE NEW ZEALAND NATIVE FROGS (LEIOPELMASPECIES)
Publisher: American Association of Zoo Veterinarians
Date: 20-09-2012
Endemicity of chytridiomycosis features pathogen overdispersion
Publisher: Wiley
Date: 29-02-2016
Abstract: Pathogens can be critical drivers of the abundance and distribution of wild animal populations. The presence of an overdispersed pathogen load distribution between hosts (where few hosts harbour heavy parasite burdens and light infections are common) can have an important stabilizing effect on host-pathogen dynamics where infection intensity determines pathogenicity. This may potentially lead to endemicity of an introduced pathogen rather than extirpation of the host and/or pathogen. Overdispersed pathogen load distributions have rarely been considered in wild animal populations as an important component of the infection dynamics of microparasites such as bacteria, viruses, protozoa and fungi. Here we examined the abundance, distribution and transmission of the model fungal pathogen Batrachochytrium dendrobatidis (Bd, cause of hibian chytridiomycosis) between wild-caught Litoria rheocola (common mist frogs) to investigate the effects of an overdispersed pathogen load distribution on the host population in the wild. We quantified host survival, infection incidence and recovery probabilities relative to infectious burden, and compared the results of models where pathogen overdispersion either was or was not considered an important feature of host-pathogen dynamics. We found the distribution of Bd load between hosts to be highly overdispersed. We found that host survival was related to infection burden and that accounting for pathogen overdispersion allowed us to better understand infection dynamics and their implications for disease control. In addition, we found that the pattern of host infections and recoveries varied markedly with season whereby (i) infections established more in winter, consistent with temperature-dependent effects on fungal growth, and (ii) recoveries (loss of infection) occurred frequently in the field throughout the year but were less likely in winter. Our results suggest that pathogen overdispersion is an important feature of endemic chytridiomycosis and that intensity of infection determines disease impact. These findings have important implications for our understanding of chytridiomycosis dynamics and the application of management strategies for disease mitigation. We recommend quantifying in idual infectious burdens rather than infection state where possible in microparasitic diseases.
Application of the survey protocol for chytridiomycosis to Queensland, Australia
Publisher: Inter-Research Science Center
Date: 25-11-2010
DOI: 10.3354/DAO02272
Abstract: Spread of the hibian chytrid fungus Batrachochytrium dendrobatidis (Bd), which causes chytridiomycosis, has resulted in the extinction of frogs, but the distribution of Bd is incompletely known. We trialled the survey protocol for Bd by attempting to systematically map its distribution in Queensland, Australia. Bd was easily detected in known infected areas, such as the Wet Tropics and South East Queensland. It was not detected in bioregions adjacent to, but inland from or to the north of, infected regions: Einasleigh Uplands and Cape York adjacent to the infected Wet Tropics and Brigalow Belt South adjacent to the infected South East Queensland bioregion. These regions where Bd was not detected have bordered infected regions for between 15 yr (in northern Queensland) and 30 yr (in southern Queensland), and so they define the geographical limits of Bd with regard to the long-term environmental conditions in Queensland. The Gulf Plains, a bioregion distant from infected bioregions, was also negative. Bd was confined to rainforest and bordering habitats, such as wet eucalypt forests. Infections were largely confined to permanent water-associated species, consistent with this being an important cause of this group having the greatest declines. Our data supports biogeographic climatic models that show much of inland and northern Australia to be too hot and dry to support Bd. As there is limited opportunity for Bd to spread further in Queensland, the priority for management is reducing the impact of Bd in affected populations and assisting frogs to disperse into their former distributions. Given that the survey protocol has been applied successfully in Australia it may be useful for mapping the distribution of Bd in other parts of the world.
Disease-associated change in an amphibian life-history trait
Publisher: Springer Science and Business Media LLC
Date: 14-07-2017
DOI: 10.1007/S00442-017-3911-7
Abstract: Emerging pathogens can drive evolutionary shifts in host life-history traits, yet this process remains poorly documented in vertebrate hosts. Amphibian chytridiomycosis, caused by infection with the fungal pathogen Batrachochytrium dendrobatidis (Bd), is the worst recorded wildlife disease and has caused the extinction of over 100 species across multiple continents. A similar number of additional species have experienced mass declines and Bd remains a major source of mortality in many populations of declined species now persisting with the pathogen. Life-history theory predicts that increased extrinsic mortality in Bd-infected populations may alter hibian life-history traits, but this has not been examined. Here, we investigate whether population Bd status is associated with age and size at maturity by comparing long-exposed Bd-infected populations, Bd-free populations, and museum specimens collected prior to Bd emergence for the endangered Australian frog Litoria verreauxii alpina. We show that Bd-infected populations have a higher proportion of males that mature at 1 year of age, and females that mature at 2 years of age, compared to Bd-free populations. Earlier maturation was associated with reduced size at maturity in males. Consistent with life-history theory, our findings may represent an adaptive evolutionary shift towards earlier maturation in response to high Bd-induced mortality. To our knowledge, this study provides the first evidence for a post-metamorphic Bd-associated shift in an hibian life-history trait. Given high mortality in other Bd-challenged species, we suggest that chytridiomycosis may be a substantial new selection pressure shaping life-history traits in impacted hibian species across multiple continents.
Polymorphic repetitive loci of the amphibian pathogen Batrachochytrium dendrobatidis
Publisher: Inter-Research Science Center
Date: 03-11-2011
DOI: 10.3354/DAO02396
Abstract: Batrachochytrium dendrobatidis (Bd), the cause of a fatal fungal skin disease of hibians that has led to massive die-offs, global declines and extinctions, has spread internationally as a pandemic clone with low genetic ersity. A need exists to develop highly polymorphic markers to determine centers of origin and patterns of spread to assist in the development of management strategies. Comparison of paralogous sequences, obtained from the 2 sequenced Bd genomes, indicates useful levels of inter-strain polymorphism in repetitive fragments. We assessed 6 repetitive loci for variation within and among Australian isolates using standard fragment analysis and capillary electrophoresis-single strand conformation polymorphism (CE-SSCP) analysis. Confirmation of inter-isolate polymorphism was achieved for 2 marker systems, highlighting the potential of repetitive loci for the development of polymorphic markers in Bd. In addition, we found that repetitive loci in Bd include possible orthologs of virulence-related genes from pathogenic fungi.
Experimental Infection and Repeat Survey Data Indicate the Amphibian Chytrid Batrachochytrium dendrobatidis May Not Occur on Freshwater Crustaceans in Northern Queensland, Australia
Publisher: Springer Science and Business Media LLC
Date: 07-02-2007
Female dispersal and relatedness structure in common wombats ( Vombatus ursinus )
Publisher: Wiley
Date: 03-2002
Treatment trial of clinically ill corroboree frogs with chytridiomycosis with two triazole antifungals and electrolyte therapy
Publisher: Springer Science and Business Media LLC
Date: 06-08-2015
DOI: 10.1007/S11259-015-9642-5
Abstract: Chytridiomycosis caused by the pathogen Batrachochytrium dendrobatidis is an important cause of hibian declines globally, and is the worst pathogen on record for causing bio ersity loss. The critically endangered southern corroboree frog, Pseudophryne corroboree, is functionally extinct in the wild and is surviving in captive assurance colonies. These captive colonies must remain disease free, and there is no known treatment for corroboree frogs with terminal chytridiomycosis. In this study we tested two triazole antifungals (itraconazole and voriconazole) coupled with aggressive electrolyte therapy on moribund corroboree frogs with severe chytridiomycosis. Six moribund frogs were given 20 mL baths of 0.5 μg/mL itraconazole for 5 min/day for 5 days coupled with electrolyte injections every 8 h for 3 days followed by every 12 h for 3 days. Six other moribund frogs were given 1 mL drops of 1.25 μg/mL voriconazole daily for 7 days coupled with the aggressive electrolyte therapy. While only one animal survived this treatment regime, time until death was extended for all animals by at least 3 days and infection load decreased by an average of 89.3%. Our results suggest there is potential for recovery of terminally ill P. corroboree, and we suggest further trials include antibiotics as well as exploring variations on the above treatment regime with other antifungals.
Survival, gene and metabolite responses of Litoria verreauxii alpina frogs to fungal disease chytridiomycosis
Publisher: Springer Science and Business Media LLC
Date: 06-03-2018
Abstract: The fungal skin disease chytridiomycosis has caused the devastating decline and extinction of hundreds of hibian species globally, yet the potential for evolving resistance, and the underlying pathophysiological mechanisms remain poorly understood. We exposed 406 naïve, captive-raised alpine tree frogs ( Litoria verreauxii alpina ) from multiple populations (one evolutionarily naïve to chytridiomycosis) to the aetiological agent Batrachochytrium dendrobatidis in two concurrent and controlled infection experiments. We investigated (A) survival outcomes and clinical pathogen burdens between populations and clutches, and (B) in idual host tissue responses to chytridiomycosis. Here we present multiple interrelated datasets associated with these exposure experiments, including animal signalment, survival and pathogen burden of 355 animals from Experiment A, and the following datasets related to 61 animals from Experiment B: animal signalment and pathogen burden raw RNA-Seq reads from skin, liver and spleen tissues de novo assembled transcriptomes for each tissue type raw gene expression data annotation data for each gene and raw metabolite expression data from skin and liver tissues. These data provide an extensive baseline for future analyses.
Tick Paralysis in Spectacled Flying-Foxes (Pteropus conspicillatus) in North Queensland, Australia: Impact of a Ground-Dwelling Ectoparasite Finding an Arboreal Host
Publisher: Public Library of Science (PLoS)
Date: 16-09-2013
Monitoring of wild birds for Newcastle disease virus in north Queensland, Australia
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.PREVETMED.2011.08.013
Abstract: Wild aquatic birds (WABs) are considered as reservoir hosts for Newcastle disease viruses (NDVs) and may act as vectors for transferring these viruses to poultry, causing outbreaks of disease. A 3-year epidemiological study was conducted on WABs of north Queensland from April 2007 to March 2010. Swab and fresh moist faecal s les of WABs were screened to detect Newcastle disease viral (NDV) RNA by one-step real time reverse transcriptase polymerase chain reaction (rRT-PCR) in multiplex primers, targeting the matrix gene. The potential reactor s les in rRT-PCR were processed for sequencing of the different NDV genes using conventional PCR. The overall NDV RNA prevalence was 3.5% for live bird s les (N=1461) and 0.4% for faecal s les (N=1157). Plumed whistling ducks (PWDs) had a higher prevalence (4.2%) than Pacific black ducks (PBDs) (0.9%) (χ(2) test, p=0.001). Univariate and multivariate logistic regression analyses were used to estimate the association between the proportion of reactor and non-reactor NDV RNA s les of PWDs and potential risk factors. The odds of reactor s les were 2.7 (95% Confidence Interval 1.5-4.9) times more likely in younger than older ducks (p=0.001) (data set B, multivariate analysis). Both NDV RNA class-one and class-two types were identified in s les of WABs (12 and 59, respectively) (Supplementary Table 1). Phylogenetic analysis of the matrix gene identified two reactor sequences of class-one type NDV RNA (PWD-48 and 55) which were closely related to the sequences of Australian Ibis and duck isolates (Fig. 2). Another reactor s le sequence was determined as class-two type NDV RNA (PWD-46, avirulent) based on analysis of the matrix and fusion genes which was more similar to the sequences of Australian I-2 progenitor virus and vaccine strain virus (Figs. 3 and 4). Our findings of higher prevalence in PWDs along with confirmation of class-one and class-two type NDV RNAs will significantly contribute to the design of surveillance programs for NDVs in northern Australia.
Declining amphibians might be evolving increased reproductive effort in the face of devastating disease
Publisher: Wiley
Date: 24-08-2021
DOI: 10.1111/EVO.14327
Abstract: The devastating infectious disease chytridiomycosis has caused declines of hibians across the globe, yet some populations are persisting and even recovering. One understudied effect of wildlife disease is changes in reproductive effort. Here, we aimed to understand if the disease has plastic effects on reproduction and if reproductive effort could evolve with disease endemism. We compared the effects of experimental pathogen exposure (trait plasticity) and population-level disease history (evolution in trait baseline) on reproductive effort using gametogenesis as a proxy in the declining and endangered frog Litoria verreauxii alpina. We found that unexposed males from disease-endemic populations had higher reproductive effort, which is consistent with an evolutionary response to chytridiomycosis. We also found evidence of trait plasticity, where males and females were affected differently by infection: pathogen exposed males had higher reproductive effort (larger testes), whereas females had reduced reproductive effort (smaller and fewer developed eggs) regardless of the population of origin. Infectious diseases can cause plastic changes in the reproductive effort at an in idual level, and population-level disease exposure can result in changes to baseline reproductive effort therefore, in idual- and population-level effects of disease should be considered when designing management and conservation programs for threatened and declining species.
Survey for the amphibian chytrid Batrachochytrium dendrobatidis in Hong Kong in native amphibians and in the international amphibian trade
Publisher: Inter-Research Science Center
Date: 13-12-2007
DOI: 10.3354/DAO01861
Abstract: Chytridiomycosis, caused by the pathogen Batrachochytrium dendrobatidis, is responsible for many hibian declines and has been identified in wild hibian populations on all continents where they exist, except for Asia. In order to assess whether B. dendrobatidis is present on the native hibians of Hong Kong, we s led wild populations of Amolops hongkongensis, Paa exilispinosa, P. spinosa and Rana chloronota during 2005-2006. Amphibians infected with B. dendrobatidis have been found in the international trade, so we also examined the extent and nature of the hibian trade in Hong Kong during 2005-2006, and assessed whether B. dendrobatidis was present in imported hibians. All 274 in iduals of 4 native hibian species s led tested negative for B. dendrobatidis, giving an upper 95% confidence limit for prevalence of 1.3%. Approximately 4.3 million hibians of 45 species from 11 countries were imported into Hong Kong via air over 12 mo we did not detect B. dendrobatidis on any of 137 imported hibians s led. As B. dendrobatidis generally occurs at greater than 5% prevalence in infected populations during favorable environmental conditions, native hibians in Hong Kong appear free of B. dendrobatidis, and may be at severe risk of impact if it is introduced. Until it is established that the pathogen is present in Hong Kong, management strategies should focus on preventing it from being imported and decreasing the risk of it escaping into the wild hibian populations if imported. Further research is needed to determine the status of B. dendrobatidis in Hong Kong with greater certainty.
Ranaviruses and reptiles
Publisher: PeerJ
Date: 12-12-2018
DOI: 10.7717/PEERJ.6083
Abstract: Ranaviruses can infect many vertebrate classes including fish, hibians and reptiles, but for the most part, research has been focused on non-reptilian hosts, hibians in particular. More recently, reports of ranaviral infections of reptiles are increasing with over 12 families of reptiles currently susceptible to ranaviral infection. Reptiles are infected by ranaviruses that are genetically similar to, or the same as, the viruses that infect hibians and fish however, physiological and ecological differences result in differences in study designs. Although ranaviral disease in reptiles is often influenced by host species, viral strain and environmental differences, general trends in pathogenesis are emerging. More experimental studies using a variety of reptile species, life stages and routes of transmission are required to unravel the complexity of wild ranavirus transmission. Further, our understanding of the reptilian immune response to ranaviral infection is still lacking, although the considerable amount of work conducted in hibians will serve as a useful guide for future studies in reptiles.
Chytridiomycosis in frogs of Mount Gede Pangrango, Indonesia
Publisher: Inter-Research Science Center
Date: 22-12-2008
DOI: 10.3354/DAO01981
Abstract: Batrachochytrium dendrobatidis (Bd) is a fungus recognised as one of the causes of global hibian population declines. To assess its occurrence, we conducted PCR diagnostic assays of 147 swab s les, from 13 species of frogs from Mount Gede Pangrango National Park, Indonesia. Four swab s les, from Rhacophorus javanus, Rana chalconota, Leptobrachium hasseltii and Limnonectes microdiscus, were positive for Bd and had low to moderate levels of infection. The s le from L. hasseltii was from a tadpole with mouthpart deformities and infection was confirmed by histology and immunohistochemistry. An additional s le from Leptophryne cruentata showed a very low level of infection (< or = 1 zoospore equivalent). This is the first record of Bd in Indonesia and in Southeast Asia, dramatically extending the global distribution of Bd, with important consequences for international hibian disease control, conservation and trade. Consistent with declines in hibian populations caused by Bd in other parts of the world, evidence exists for the decline and possible extirpation of hibian populations at high elevations and some decline with recovery of populations at lower elevations on this mountain. Therefore, it is essential to manage Bd in Indonesia where it is likely to be threatening hibian populations. This will require a national strategy to mitigate the spread of Bd in Indonesia and neighboring countries as well as the impact of that spread. It is also important to collect information on the extent of the impact of Bd on frog populations in Indonesia.
Minimising exposure of amphibians to pathogens during field studies
Publisher: Inter-Research Science Center
Date: 27-01-2010
DOI: 10.3354/DAO02162
Abstract: Many of the recent global hibian mass mortalities, declines and extinctions have been attributed to the emerging infectious disease chytridiomycosis. There have been mass mortalities due to ranaviral disease but no major declines or extinctions. Controlling the transmission and spread of disease is of utmost importance, especially where there is the potential for human involvement. We have reviewed current hygiene guidelines for working with wild frogs, identified potential flaws and recommended those most suitable and effective for the field environment. Our within-site hygiene measures aim to reduce the risk of transmission among in iduals. These measures encompass the capture, handling and holding of hibians, skin disinfection before and after invasive procedures, marking frogs, sealing open wounds and treatment of accessory equipment. Our between-site hygiene measures aim to mitigate the risk of pathogen spread among populations. We have designed a risk calculator to help simplify and standardise the decision-making process for determining the level of risk and appropriate risk mitigation strategies to reduce the risk of increasing pathogen spread above background levels. Calculation of an overall risk score for pathogen spread takes into account the prior activity of field workers, the proposed activity, remoteness of the site, presence of known pathogens and the consequences of increased pathogen spread for hibians in a given area.
Chytridiomycosis
Publisher: Springer International Publishing
Date: 2018
Development and worldwide use of non-lethal, and minimal population-level impact, protocols for the isolation of amphibian chytrid fungi
Publisher: Springer Science and Business Media LLC
Date: 17-05-2018
DOI: 10.1038/S41598-018-24472-2
Abstract: Parasitic chytrid fungi have emerged as a significant threat to hibian species worldwide, necessitating the development of techniques to isolate these pathogens into culture for research purposes. However, early methods of isolating chytrids from their hosts relied on killing hibians. We modified a pre-existing protocol for isolating chytrids from infected animals to use toe clips and biopsies from toe webbing rather than euthanizing hosts, and distributed the protocol to researchers as part of the Bio ERsA project RACE here called the RML protocol. In tandem, we developed a lethal procedure for isolating chytrids from tadpole mouthparts. Reviewing a database of use a decade after their inception, we find that these methods have been applied across 5 continents, 23 countries and in 62 hibian species. Isolation of chytrids by the non-lethal RML protocol occured in 18% of attempts with 207 fungal isolates and three species of chytrid being recovered. Isolation of chytrids from tadpoles occured in 43% of attempts with 334 fungal isolates of one species ( Batrachochytrium dendrobatidis ) being recovered. Together, these methods have resulted in a significant reduction and refinement of our use of threatened hibian species and have improved our ability to work with this group of emerging pathogens.
An unprecedented cluster of Australian bat lyssavirus in Pteropus conspicillatus indicates pre‐flight flying fox pups are at risk of mass infection
Publisher: Wiley
Date: 20-04-2020
DOI: 10.1111/ZPH.12703
Genetic potential for disease resistance in critically endangered amphibians decimated by chytridiomycosis
Publisher: Wiley
Date: 23-10-2019
DOI: 10.1111/ACV.12459
Characterization of MHC class IA in the endangered southern corroboree frog
Publisher: Springer Science and Business Media LLC
Date: 27-12-2017
DOI: 10.1007/S00251-016-0965-3
Abstract: Southern corroboree frogs (Pseudophryne corroboree) have declined to near extinction in the wild after the emergence of the hibian chytrid fungus Batrachochytrium dendrobatidis in southeastern Australia in the 1980s. A major captive breeding and reintroduction program is underway to preserve this iconic species, but improving resistance to B. dendrobatidis would help the wild population to be self-sustaining. Using 3' and 5' rapid lification of complementary DNA ends (RACE), we characterized the major histocompatibility complex (MHC) class IA locus in this species. We then used sequences generated from RACE to design primers to lify the peptide-binding region (PBR) of this functional genetic marker. Finally, we analysed the ersity, phylogeny, and selection patterns of PBR sequences from four P. corroboree populations and compared this with other hibian species. We found moderately high MHC class IA genetic ersity in this species and evidence of strong positive and purifying selection at sites that are associated with putative PBR pockets in other species, indicating that this gene region may be under selection for resistance to Bd. Future studies should focus on identifying alleles associated with Bd resistance in P. corroboree by performing a Bd laboratory challenge study to confirm the functional importance of our genetic findings and explore their use in artificial selection or genetic engineering to increase resistance to chytridiomycosis.
Susceptibility of amphibians to chytridiomycosis is associated with MHC class II conformation
Publisher: The Royal Society
Date: 22-04-2015
Abstract: The pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd) can cause precipitous population declines in its hibian hosts. Responses of in iduals to infection vary greatly with the capacity of their immune system to respond to the pathogen. We used a combination of comparative and experimental approaches to identify major histocompatibility complex class II (MHC-II) alleles encoding molecules that foster the survival of Bd-infected hibians. We found that Bd-resistant hibians across four continents share common amino acids in three binding pockets of the MHC-II antigen-binding groove. Moreover, strong signals of selection acting on these specific sites were evident among all species co-existing with the pathogen. In the laboratory, we experimentally inoculated Australian tree frogs with Bd to test how each binding pocket conformation influences disease resistance. Only the conformation of MHC-II pocket 9 of surviving subjects matched those of Bd-resistant species. This MHC-II conformation thus may determine hibian resistance to Bd, although other MHC-II binding pockets also may contribute to resistance. Rescuing hibian bio ersity will depend on our understanding of hibian immune defence mechanisms against Bd. The identification of adaptive genetic markers for Bd resistance represents an important step forward towards that goal.
Anthelmintic efficacy of five tropical native Australian plants against Haemonchus contortus and Trichostrongylus colubriformis in experimentally infected goats (Capra hircus)
Publisher: Elsevier BV
Date: 06-2012
DOI: 10.1016/J.VETPAR.2011.12.040
Abstract: The study of the anthelmintic properties of plants rich in plant secondary metabolites can provide ecologically sound methods for the treatment of parasites on grazing animals. The purpose of the present study was to evaluate the anthelmintic effect of five tropical native Australian plant species rich in plant secondary metabolites on adult Haemonchus contortus and Trichostrongylus colubriformis in experimentally infected goats. Thirty young, nematode-free goats were infected with 2500 H. contortus and 5000 T. colubriformis infective larvae thrice weekly for a week (day 1-7 of the experiment). On day 27 after first infection, the goats were allocated into six groups of five animals per group. From day 28 to day 35, fresh leaves from Acacia salicina, Acacia nilotica, Eucalyptus corymbia, Casuarina cunninghamiana and Eucalyptus drepanophylla were included in the goats diet. Five groups were offered leaves from one of these plant species and one group, the untreated control, received only the basal diet formulated with 20% Medicago sativa and 80% Avena sativa. Following plant material administration, the goats were monitored daily until day 40 and then slaughtered on day 41. Total faecal worm egg output, total production of larvae recovered from faecal cultures, total post-mortem worm burdens and the per capita fecundity of female worms were estimated. The toxicity of the plant species for the goats was measured by histopathological analyses of liver and kidney s les. Results showed that goats feeding on the plant material rich in plant secondary metabolites had significantly lower egg output compared to the control goats (P 0.05), the per capita fecundity was significantly reduced by E. corymbia, A. nilotica and A. salicina (P<0.05). No signs of toxicity were detected in the liver or kidney s les. It is concluded that goats can benefit from the short-term ingestion of plant secondary metabolites, which reduce the total faecal egg output and thus decrease the potential for re-infection from the pasture.
Engineering a future for amphibians under climate change
Publisher: Wiley
Date: 02-02-2011
Underestimated ranges and overlooked refuges from amphibian chytridiomycosis
Publisher: Wiley
Date: 02-05-2013
DOI: 10.1111/DDI.12091
Sodium hypochlorite denatures the DNA of the amphibian chytrid fungus Batrachochytrium dendrobatidis
Publisher: Inter-Research Science Center
Date: 19-06-2008
DOI: 10.3354/DAO01919
Abstract: Batrachochytrium dendrobatidis, an aquatic hibian fungus, has been implicated in many hibian declines and extinctions. A real-time polymerase chain reaction (PCR) TaqMan assay is now used to detect and quantify B. dendrobatidis on hibians and other substrates via tissue s les, swabbing and filtration. The extreme sensitivity of this diagnostic test makes it necessary to rigorously avoid cross-contamination of s les, which can produce false positives. One technique used to eliminate contamination is to destroy the contaminating DNA by chemical means. We tested 3 concentrations of sodium hypochlorite (NaOCl) (1, 6 and 12%) over 4 time periods (1, 6, 15 and 24 h) to determine if NaOCl denatures B. dendrobatidis DNA sufficiently to prevent its recognition and lification in PCR tests for the fungus. Soaking in 12% NaOCl denatured 100% of DNA within 1 h. Six percent NaOCl was on average 99.999% effective across all exposure periods, with only very low numbers of zoospores detected following treatment. One percent NaOCl was ineffective across all treatment periods. Under ideal, clean conditions treatment with 6% NaOCl may be sufficient to destroy DNA and prevent cross-contamination of s les however, we recommend treatment with 12% NaOCl for 1 h to be confident all B. dendrobatidis DNA is destroyed.
Recent Asian origin of chytrid fungi causing global amphibian declines
Publisher: American Association for the Advancement of Science (AAAS)
Date: 11-05-2018
Abstract: Species in the fungal genus Batrachochytrium are responsible for severe declines in the populations of hibians globally. The sources of these pathogens have been uncertain. O'Hanlon et al. used genomics on a panel of more than 200 isolates to trace the source of the frog pathogen B. dendrobatidis to a hyper erse hotspot in the Korean peninsula (see the Perspective by Lips). Over the past century, the trade in hibian species has accelerated, and now all lineages of B. dendrobatidis occur in traded hibians the fungus has become ubiquitous and is ersifying rapidly. Science , this issue p. 621 see also p. 604
Defects in Host Immune Function in Tree Frogs with Chronic Chytridiomycosis
Publisher: Public Library of Science (PLoS)
Date: 11-09-2014
Effect of season and temperature on mortality in amphibians due to chytridiomycosis
Publisher: Wiley
Date: 07-2004
DOI: 10.1111/J.1751-0813.2004.TB11137.X
Abstract: To investigate the distribution and incidence of chytridiomycosis in eastern Australian frogs and to examine the effects of temperature on this disease. A pathological survey and a transmission experiment were conducted. Diagnostic pathology examinations were performed on free-living and captive, ill and dead hibians collected opportunistically from eastern Australia between October 1993 and December 2000. We conducted a transmission experiment in the laboratory to investigate the effects of temperature: eight great barred frogs (Mixophyes fasciolatus) exposed to zoospores of Batrachochytrium dendrobatidis and six unexposed frogs were housed in idually in each of three rooms held at 17 degrees C, 23 degrees C and 27 degrees C. Chytridiomycosis was the cause of death or morbidity for 133 (55.2%) of 241 free-living hibians and for 66 (58.4%) of 113 captive hibians. This disease occurred in 34 hibian species, was widespread around the eastern seaboard of Australia and affected hibians in a variety of habitats at high and low altitudes on or between the Great Dividing Range and the coast. The incidence of chytridiomycosis was higher in winter, with 53% of wild frogs from Queensland and New South Wales dying in July and August. Other diseases were much less common and were detected mostly in spring and summer. In experimental infections, lower temperatures enhanced the pathogenicity of B. dendrobatidis in M. fasciolatus. All 16 frogs exposed to B. dendrobatidis at 17 degrees C and 23 degrees C died, whereas 4 of 8 frogs exposed at 27 degrees C survived. However, the time until death for the frogs that died at 27 degrees C was shorter than at the lower temperatures. Infections in survivors were eliminated by 98 days. Chytridiomycosis is a major cause of mortality in free-living and captive hibians in Australia and mortality rate increases at lower temperatures.
Evidence of Effects of Endemic Chytridiomycosis on Host Survival, Behavior, and Emigration: Reply to Schmidt
Publisher: Wiley
Date: 14-05-2010
The mitochondrial 12S gene is a suitable marker of populations of Sarcoptes scabiei from wombats, dogs and humans in Australia
Publisher: Springer Science and Business Media LLC
Date: 23-01-2002
DOI: 10.1007/S00436-001-0556-5
Abstract: We sequenced part of the mitochondrial 12S ribosomal RNA gene of 23 specimens of Sarcoptes scabiei from eight wombats, one dog and three humans. Twelve of the 326 nucleotide positions varied among these mites and there were nine haplotypes (sequences) that differed by 1-8 nucleotides. Phylogenetic analyses indicated that these mites were from two lineages: (1) mites from wombats from Victoria, Australia, and mites from the humans and dog from the Northern Territory, Australia (haplotypes 1-4, 9) and (2) mites from the humans and dog from the Northern Territory (haplotypes 5-8). Mites from the three different hosts (wombats, a dog and humans) had not erged phylogenetically rather, these mites had similar 12S sequences. Thus, we conclude that these mites from wombats, humans and a dog are closely related, and that they erged from a common ancestor relatively recently. This conclusion is consistent with the argument that people and/or their dogs introduced to Australia the S. scabiei mites that infect wombats in Australia . So, S. scabiei, which has been blamed for the extinction of populations of wombats in Australia, may be a parasitic mite that was introduced to Australia with people and/or their dogs. These data show that the mitochondrial 12S rRNA gene may be a suitable population marker of S. scabiei from wombats, dogs and humans in Australia.
Using Terminal Transferase-mediated dUTP Nick End-labelling (TUNEL) and Caspase 3/7 Assays to Measure Epidermal Cell Death in Frogs with Chytridiomycosis
Publisher: MyJove Corporation
Date: 16-05-2018
DOI: 10.3791/57345
Molecular epidemiology of influenza A (H5N1) viruses, Bangladesh, 2007–2011
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.PREVETMED.2013.06.003
Abstract: To investigate the origins, evolution and patterns of spread of HPAI H5N1 outbreaks in Bangladesh, we performed a phylogenetic reconstruction analysis using Bayesian methods. The analysis was conducted using 81 hemagglutinin (HA) gene sequences from the H5N1 viruses isolated in Bangladesh from 2007 to 2011, together with 264 publicly available HA sequences of clade 2.2, 2.3.2 and 2.3.4 retrieved from GenBank. Our study provides evidence that clade 2.2.2 viruses that caused outbreaks in Bangladesh were lineages independent from the viruses introduced earlier into India. Furthermore, the Bangladesh clade 2.2.2 descendents subsequently spread to India and Bhutan. This has implications for avian influenza control in southern Asia suggesting multiple routes of entry of the virus including one pathway that spread to neighboring countries via Bangladesh.
Hendra virus survival does not explain spillover patterns and implicates relatively direct transmission routes from flying foxes to horses
Publisher: Microbiology Society
Date: 06-2015
DOI: 10.1099/VIR.0.000073
Low humidity is a failed treatment option for chytridiomycosis in the critically endangered southern corroboree frog
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/WR14097
Abstract: Context One of the major drivers of the current worldwide hibian decline and extinction crisis is the spread of the hibian chytrid fungus, Batrachochytrium dendrobatidis (Bd). Captive assurance colonies may be the only lifeline for some species. Current antifungal chemotherapies can be effective for clearing infection but may have detrimental side effects. The only non-chemotherapeutic treatment that has been clinically tested is heat, which is impractical for cold-adapted species. The fungus does not survive desiccation, and therefore a plausible alternative non-chemotherapeutic treatment would be a low-humidity regimen. Aims We tested the efficacy of a low-humidity treatment regimen for treating Bd-infected animals of the critically endangered species Pseudophryne corroboree. This species has high tolerance of dry environments, and is thus an ideal candidate for this treatment trial. Methods Forty frogs were exposed to 1 × 106 zoospores. At three weeks after exposure access to water was reduced to once daily for 10 days for 20 animals. Ten of these animals were also rinsed daily with the aim of removing zoospores. Key results The drying regimen neither increased survival nor decreased infection load, and treatment may have hastened mortality. All infected frogs died between 21 and 80 days after exposure, except one untreated frog. Conclusions Our results suggest that a drying regimen is not a viable treatment for chytridiomycosis. Infection may decrease the host’s ability to cope with water stress. Implications The failed drying treatment in P. corroboree suggests that drying is not an appropriate treatment for chytridiomycosis and treatment efforts should be focussed on chemotherapies for cold-adapted species. P. corroboree is a critically endangered species for which chytridiomycosis is the primary cause of decline, yet few experiments have been carried out on this species with regards to chytridiomycosis. All experimental information about this species and disease will benefit the management and protection of the species.
High adult mortality in disease-challenged frog populations increases vulnerability to drought
Publisher: Wiley
Date: 15-08-2016
Abstract: Pathogen emergence can drive major changes in host population demography, with implications for population dynamics and sensitivity to environmental fluctuations. The hibian disease chytridiomycosis, caused by infection with the fungal pathogen Batrachochytrium dendrobatidis (Bd), is implicated in the severe decline of over 200 hibian species. In species that have declined but not become extinct, Bd persists and can cause substantial ongoing mortality. High rates of mortality associated with Bd may drive major changes in host demography, but this process is poorly understood. Here, we compared population age structure of Bd-infected populations, Bd-free populations and museum specimens collected prior to Bd emergence for the endangered Australian frog, Litoria verreauxii alpina (alpine tree frog). We then used population simulations to investigate how pathogen-associated demographic shifts affect the ability of populations to persist in stochastic environments. We found that Bd-infected populations have a severely truncated age structure associated with very high rates of annual adult mortality. Near-complete annual adult turnover in Bd-infected populations means that in iduals breed once, compared with Bd-free populations where adults may breed across multiple years. Our simulations showed that truncated age structure erodes the capacity of populations to withstand periodic recruitment failure a common challenge for species reproducing in uncertain environments. We document previously undescribed demographic shifts associated with a globally emerging pathogen and demonstrate how these shifts alter host ecology. Truncation of age structure associated with Bd effectively reduces host niche width and can help explain the contraction of L. v. alpina to perennial waterbodies where the risk of drought-induced recruitment failure is low. Reduced capacity to tolerate other sources of mortality may explain variation in decline severity among other chytridiomycosis-challenged species and highlights the potential to mitigate disease impacts through minimizing other sources of mortality.
Dynamics of Chytridiomycosis during the Breeding Season in an Australian Alpine Amphibian
Publisher: Public Library of Science (PLoS)
Date: 02-12-2015
Survey protocol for detecting chytridiomycosis in all Australian frog populations
Publisher: Inter-Research Science Center
Date: 07-07-2008
DOI: 10.3354/DAO01923
Abstract: Spread of the hibian chytrid fungus Batrachochytrium dendrobatidis (Bd) has caused the decline and extinction of frogs, but the distribution of Bd is not completely known. This information is crucial to implementing appropriate quarantine strategies, preparing for outbreaks of chytridiomycosis due to introduction of Bd, and for directing conservation actions towards affected species. This survey protocol provides a simple and standard method for s ling all frog populations in Australia to maximise the chances of detecting Bd. In order to structure and prioritise the protocol, areas are ided by bioregion and frog species are allocated depending on the water bodies they utilize into 3 groups representing different levels of risk of exposure to Bd. Sixty in iduals per population need to be tested to achieve 95% certainty of detecting 1 positive frog, based on the minimum apparent prevalence of > or =5% in infected Australian frog populations and using a quantitative real-time TaqMan PCR test. The appropriate season to s le varies among bioregions and will ideally incorporate temperatures favourable for chytridiomycosis (e.g. maximum air temperatures generally <27 degrees C). Opportunistic collection and testing of sick frogs and tadpoles with abnormal mouth-parts should also be done to increase the probability of detecting Bd. The survey priorities in order are (1) threatened species that may have been exposed to Bd, (2) bioregions surrounding infected bioregions/ecological groups, and (3) species of frogs of unknown infection status in infected bioregions. Within these priority groups, s ling should first target ecological groups and species likely to be exposed to Bd, such as those associated with permanent water, and areas within bioregions that have high risk for Bd as indicated by climatic modelling. This protocol can be adapted for use in other countries and a standard protocol will enable comparison among hibian populations globally.
Inguinal and axillary dermatitis in wallabies in north Queensland due to the dermanyssid mite Thadeua serrata
Publisher: Wiley
Date: 27-11-2007
Reservoir-host amplification of disease impact in an endangered amphibian
Publisher: Wiley
Date: 12-2017
DOI: 10.1111/COBI.12830
Abstract: Emerging wildlife pathogens are an increasing threat to bio ersity. One of the most serious wildlife diseases is chytridiomycosis, caused by the fungal pathogen, Batrachochytrium dendrobatidis (Bd), which has been documented in over 500 hibian species. Amphibians vary greatly in their susceptibility to Bd some species tolerate infection, whereas others experience rapid mortality. Reservoir hosts-species that carry infection while maintaining high abundance but are rarely killed by disease-can increase extinction risk in highly susceptible, sympatric species. However, whether reservoir hosts lify Bd in declining hibian species has not been examined. We investigated the role of reservoir hosts in the decline of the threatened northern corroboree frog (Pseudophryne pengilleyi) in an hibian community in southeastern Australia. In the laboratory, we characterized the response of a potential reservoir host, the (nondeclining) common eastern froglet (Crinia signifera), to Bd infection. In the field, we conducted frog abundance surveys and Bd s ling for both P. pengilleyi and C. signifera. We built multinomial logistic regression models to test whether Crinia signifera and environmental factors were associated with P. pengilleyi decline. C. signifera was a reservoir host for Bd. In the laboratory, many in iduals maintained intense infections (>1000 zoospore equivalents) over 12 weeks without mortality, and 79% of in iduals s led in the wild also carried infections. The presence of C. signifera at a site was strongly associated with increased Bd prevalence in sympatric P. pengilleyi. Consistent with disease lification by a reservoir host, P. pengilleyi declined at sites with high C. signifera abundance. Our results suggest that when reservoir hosts are present, population declines of susceptible species may continue long after the initial emergence of Bd, highlighting an urgent need to assess extinction risk in remnant populations of other declined hibian species.
Assessing spatial patterns of disease risk to biodiversity: implications for the management of the amphibian pathogen, Batrachochytrium dendrobatidis
Publisher: Wiley
Date: 17-12-2010
Batrachochytrium dendrobatidis: requirement for further isolate collection and archiving
Publisher: Inter-Research Science Center
Date: 11-05-2010
DOI: 10.3354/DAO02216
Abstract: The fungal pathogen Batrachochytrium dendrobatidis (Bd) causes the disease chytridiomycosis, which is lethal to many species of hibians worldwide. Many studies have investigated the epidemiology of chytridiomycosis in hibian populations, but few have considered possible host-pathogen coevolution. More specifically, investigations focused on the evolution of Bd, and the link with Bd virulence, are needed. Such studies, which may be important for conservation management of hibians, depend on access to Bd isolates. Here we provide a summary of known Bd isolates that have been collected and archived in various locations around the world. Of 257 Bd isolates, we found that 53% originate from ranids in the United States. In many cases, detailed information on isolate origin is unavailable, and it is unknown how many isolates are cryo-archived. We suggest the creation of a centralized database of isolate information, and we urge researchers and managers to isolate and archive Bd to facilitate future research on chytridiomycosis.
Chytrid infection and post-release fitness in the reintroduction of an endangered alpine tree frog
Publisher: Wiley
Date: 17-08-2016
DOI: 10.1111/ACV.12230
Age- and size-dependent resistance to chytridiomycosis in the invasive cane toad Rhinella marina
Publisher: Inter-Research Science Center
Date: 06-11-2018
DOI: 10.3354/DAO03278
Abstract: In Australia, the cane toad Rhinella marina and chytrid fungus Batrachochytrium dendrobatidis (Bd) are ex les of invasive species that have had dramatic impacts on native fauna. However, little is known about the interaction between Bd and cane toads. We aimed to explore the interaction of these 2 species in 3 parts. First, we collated data from the literature on Bd infection in wild cane toads. Second, we tested the susceptibility of recently metamorphosed cane toads to Bd infection. Finally, we modelled the distribution of the 2 species in Australia to identify where they overlap and, therefore, might interact. Through our data collation, we found that adult cane toads are infrequently infected and do not carry high infection burdens however, our infection experiment showed that metamorphs are highly susceptible to infection and disease, but resistance appears to increase with increasing toad size. Niche modelling revealed overlapping distributions and the potential for cane toads to be affected by chytridiomycosis in the wild. While Bd can cause mortality in small juveniles in the laboratory, warm microhabitats used by wild toads likely prevent infection, and furthermore, high mortality of juveniles is unlikely to affect the adult populations because they are highly fecund. However, to demonstrate the impact of Bd on wild cane toad populations, targeted field studies are required to assess (1) the overall impact of chytridiomycosis on recruitment especially in cooler areas more favourable for Bd and (2) whether cane toad juveniles can lify Bd exposure of native hibian species in these areas.
Emerging infectious diseases of wildlife: a critical perspective
Publisher: Elsevier BV
Date: 04-2015
Abstract: We review the literature to distinguish reports of vertebrate wildlife disease emergence with sufficient evidence, enabling a robust assessment of emergence drivers. For potentially emerging agents that cannot be confirmed, sufficient data on prior absence (or a prior difference in disease dynamics) are frequently lacking. Improved surveillance, particularly for neglected host taxa, geographical regions and infectious agents, would enable more effective management should emergence occur. Exposure to domestic sources of infection and human-assisted exposure to wild sources were identified as the two main drivers of emergence across host taxa the domestic source was primary for fish while the wild source was primary for other taxa. There was generally insufficient evidence for major roles of other hypothesized drivers of emergence.
Spread of Chytridiomycosis Has Caused the Rapid Global Decline and Extinction of Frogs
Publisher: Springer Science and Business Media LLC
Date: 10-04-2007
Terrestrial Dispersal and Potential Environmental Transmission of the Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis)
Publisher: Public Library of Science (PLoS)
Date: 30-04-2015
Related Organisations
No related organisations have been discovered for Lee Skerratt.
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Summary: Improving disease resilience in ecosystems using synthetic biology. This project aims to use the latest methods in synthetic biology to conserve species threatened by disease, through characterising and enhancing immunity. Emerging infectious diseases are a major threat to ecosystems and new methodologies are needed to fight them. Chytridiomycosis is the most devastating disease of vertebrates, causing population declines in over 200 amphibian species worldwide. The expected outcomes of the proj .... Improving disease resilience in ecosystems using synthetic biology. This project aims to use the latest methods in synthetic biology to conserve species threatened by disease, through characterising and enhancing immunity. Emerging infectious diseases are a major threat to ecosystems and new methodologies are needed to fight them. Chytridiomycosis is the most devastating disease of vertebrates, causing population declines in over 200 amphibian species worldwide. The expected outcomes of the project are improved understanding and increased immunity of frogs to chytridiomycosis and restoration of frogs into the environment. The project will demonstrate the usefulness of synthetic biology to tackle disease and preserve biodiversity in the landscape for similarly threatened wildlife in Australia and overseas. Read more Read less
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