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chironomidae bloodworms larvae as aquatic amphibian food.different species of chironomids larvae (diptera: chironomidae) so-called bloodworms are widely distributed in the sediments of all types of freshwater habitats and considered as an important food source for amphibians. in our study, three species of chironomidae (baeotendipes noctivagus, benthalia dissidens, and chironomus riparius) were identified in 23 samples of larvae from belgium, poland, russia, and ukraine provided by a distributor in belgium. we evaluated the suitability of these sample ...201424535989
trypan blue dye is an effective and inexpensive way to determine the viability of batrachochytrium dendrobatidis zoospores.batrachochytrium dendrobatidis (bd) has been implicated in hundreds of amphibian declines and is the focus of a vast amount of research. despite this, there is no reported efficient way to assess bd viability. discriminating between live and dead bd would help determine the dose of live bd zoospores and whether factors have lethal or sublethal effects on bd. we tested whether trypan blue, a common stain to discriminate live and dead cells, could be used to assess bd viability. we show that the p ...201424519684
long-term endemism of two highly divergent lineages of the amphibian-killing fungus in the atlantic forest of brazil.the recent global spread of the amphibian-killing fungus [batrachochytrium dendrobatidis (bd)] has been closely tied to anthropogenic activities; however, regional patterns of spread are not completely understood. using historical samples, we can test whether bd was a spreading or endemic pathogen in a region within a particular time frame, because those two disease states provide different predictions for the regional demographic dynamics and population genetics of bd. testing historical patter ...201424471406
a tale of two lineages: unexpected, long-term persistence of the amphibian-killing fungus in brazil.for the past 17 years, scientists have been compiling a list of amphibian species susceptible to infection by the amphibian-killing chytrid fungus, batrachochytrium dendrobatidis (bd), all over the world, with >500 species infected on every continent except antarctica (olson et al.). where bd has been found, the impacts on amphibians has been one of two types: either bd arrives into a naïve amphibian population followed by a mass die-off and population declines (e.g. lips et al.), or bd is prese ...201424471404
swabbing often fails to detect amphibian chytridiomycosis under conditions of low infection load.the pathogenic chytrid fungus, batrachochytrium dendrobatidis (denoted bd), causes large-scale epizootics in naïve amphibian populations. intervention strategies to rapidly respond to bd incursions require sensitive and accurate diagnostic methods. chytridiomycosis usually is assessed by quantitative polymerase chain reaction (qpcr) amplification of amphibian skin swabs. results based on this method, however, sometimes yield inconsistent results on infection status and inaccurate scores of infec ...201425333363
batrachochytrium dendrobatidis detected in kihansi spray toads at a captive breeding facility (kihansi, tanzania).the chytrid fungus batrachochytrium dendrobatidis (bd) is the aetiological agent of amphibian chytridiomycosis, a disease associated with global amphibian population declines. in november 2012, mass mortalities of kihansi spray toads nectophrynoides asperginis were observed at the kihansi captive breeding facility, located in the udzungwa mountains, tanzania. mortalities increased rapidly, and dead toads showed typical clinical signs of chytridiomycosis, including reddening of the skin that was ...201425266903
survey of turkey's endemic amphibians for chytrid fungus batrachochytrium dendrobatidis.we report a new survey for batrachochytrium dendrobatidis (bd) in turkey. we swabbed 228 individuals of 7 amphibian species (from 5 families) living in 2 locations (26-august national park and the turkish lakes district) in the southwestern anatolian region. the infection intensity of all the samples was determined using quantitative pcr. all 4 amphibian breeding sites and 4 amphibian species in 26-august national park were infected by bd, with the prevalence at each site ranging from 8 to 29%. ...201425266902
in vitro sensitivity of the amphibian pathogen batrachochytrium dendrobatidis to antifungal therapeutics.chytridiomycosis, a skin disease caused by batrachochytrium dendrobatidis, has caused amphibian 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 inhibito ...201425241392
detection of pathogenic batrachochytrium dendrobatidis using water filtration, animal and bait testing.the pathogen batrachochytrium dendrobatidis (bd) can be challenging to detect at endangered amphibian reintroduction sites. pre-release bd detection can be confounded by imperfect animal sampling and the absence of animals. in study 1, we used historical bd-positive sites, to concurrently evaluate water filtrates and mouth bar (tadpoles) or skin swab (caudates) samples for bd using molecular beacon realtime pcr. in study 2, during a natural outbreak, we used pcr to detect bd from zoospore-attrac ...201425231013
investigating differences across host species and scales to explain the distribution of the amphibian pathogen batrachochytrium dendrobatidis.many pathogens infect more than one host species, and clarifying how these different hosts contribute to pathogen dynamics can facilitate the management of pathogens and can lend insight into the functioning of pathogens in ecosystems. in this study, we investigated a suite of native and non-native amphibian hosts of the pathogen batrachochytrium dendrobatidis (bd) across multiple scales to identify potential mechanisms that may drive infection patterns in the colorado study system. specifically ...201425222375
heterogeneous occupancy and density estimates of the pathogenic fungus batrachochytrium dendrobatidis in waters of north america.biodiversity losses are occurring worldwide due to a combination of stressors. for example, by one estimate, 40% of amphibian species are vulnerable to extinction, and disease is one threat to amphibian populations. the emerging infectious disease chytridiomycosis, caused by the aquatic fungus batrachochytrium dendrobatidis (bd), is a contributor to amphibian declines worldwide. bd research has focused on the dynamics of the pathogen in its amphibian hosts, with little emphasis on investigating ...201425222122
extremely low prevalence of batrachochytrium dendrobatidis in frog populations from neotropical dry forest of costa rica supports the existence of a climatic refuge from disease.population declines and extinctions of numerous species of amphibians, especially stream-breeding frogs, have been linked to the emerging infectious disease chytridiomycosis, caused by the chytrid fungus, batrachochytrium dendrobatidis. in central america, most of the 34 species of the craugastor punctariolus species group have disappeared in recent years in high- and low-elevation rainforests. distribution models for b. dendrobatidis and the continuous presence of the extirpated stream-dwelling ...201425212725
defects in host immune function in tree frogs with chronic chytridiomycosis.the amphibian chytrid fungus batrachochytrium dendrobatidis (bd) has caused mass mortality leading to population declines and extinctions in many frog species worldwide. the lack of host resistance may be due to fungal immunosuppressive effects that have been observed when bd is incubated with cultured lymphocytes, but whether in vivo host immunosuppression occurs is unknown. we used a broad range of hematologic and protein electrophoresis biomarkers, along with various functional tests, to asse ...201425211333
inhibition of local immune responses by the frog-killing fungus batrachochytrium dendrobatidis.amphibians are suffering unprecedented global declines. a leading cause is the infectious disease chytridiomycosis caused by the chytrid fungus batrachochytrium dendrobatidis. chytridiomycosis is a skin disease which disrupts transport of essential ions leading to death. soluble factors produced by b. dendrobatidis impair amphibian and mammalian lymphocytes in vitro, but previous studies have not shown the effects of these inhibitory factors in vivo. to demonstrate in vivo inhibition of immunity ...201425156734
designing screening protocols for amphibian disease that account for imperfect and variable capture rates of individuals.the amphibian chytrid fungus, batrachochytrium dendrobatidis, is one of the main factors in global amphibian decline. accurate knowledge of its presence and prevalence in an area is needed to trigger conservation actions. however, imperfect capture rates determine the number of individuals caught and tested during field surveys, and contribute to the uncertainty surrounding estimates of prevalence. screening programs should be planned with the objective of minimizing such uncertainty. we show ho ...201425154107
batrachochytrium dendrobatidis infection dynamics vary seasonally in upstate new york, usa.the amphibian disease chytridiomycosis, caused by the fungus batrachochytrium dendrobatidis (bd), is a major cause of worldwide amphibian declines and extinctions. although several studies indicate that bd prevalence and infection intensity vary seasonally, temporal variation of bd at high-latitude sites, such as the northeastern usa, is still poorly characterized. we screened amphibians for bd monthly at 2 study sites in new york state from april to october 2011 and used quantitative polymerase ...201425144117
baseline cutaneous bacteria of free-living new zealand native frogs (leiopelma archeyi and leiopelma hochstetteri) and implications for their role in defense against the amphibian chytrid (batrachochytrium dendrobatidis).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 nativ ...201425121401
detection of the emerging amphibian pathogens batrachochytrium dendrobatidis and ranavirus in russia.in a population of the european common toad bufo bufo from a rural pond in the region of lake glubokoe regional reserve in moscow province, russia, unexplained mass mortality events involving larvae and metamorphs have been observed over a monitoring period of >20 yr. we tested toads from this and a nearby site for the emerging amphibian pathogens batrachochytrium dendrobatidis (bd) and ranavirus (rv). both pathogens were detected, and at the rural pond site, with the above-noted losses and decl ...201425114047
effects of amphibian chytrid fungus exposure on american toads in the presence of an insecticide.abiotic factors such as pesticides may alter the impact of a pathogen on hosts, which could have implications for host-pathogen interactions and may explain variation in disease outbreaks in nature. in the present laboratory experiment, american toad (anaxyrus americanus) metamorphs were exposed to the amphibian chytrid fungal pathogen batrachochytrium dendrobatidis (bd) and environmentally relevant concentrations of the insecticide malathion to determine whether malathion altered the effects of ...201425099070
the effects of the amphibian chytrid fungus, insecticide exposure, and temperature on larval anuran development and survival.chytridiomycosis, a disease caused by batrachochytrium dendrobatidis (bd), has been implicated as a cause of amphibian declines. susceptibility may be influenced by environmental factors that suppress the immune response. the authors conducted a laboratory study to examine the effect of temperature, insecticide exposure, and bd exposure during larval anuran development. the authors examined the consequences of exposure to bd, an insecticide (carbaryl or malathion), and static or fluctuating temp ...201425098758
unexpected rarity of the pathogen batrachochytrium dendrobatidis in appalachian plethodon salamanders: 1957-2011.widespread population declines in terrestrial plethodon salamanders occurred by the 1980s throughout the appalachian mountains, the center of global salamander diversity, with no evident recovery. we tested the hypothesis that the historic introduction and spread of the pathogenic fungus batrachochytrium dendrobatidis (bd) into the eastern us was followed by plethodon population declines. we expected to detect elevated prevalence of bd prior to population declines as observed for central america ...201425084159
effects of pesticide exposure and the amphibian chytrid fungus on gray treefrog (hyla chrysoscelis) metamorphosis.pesticides are detectable in most aquatic habitats and have the potential to alter host-pathogen interactions. the amphibian chytrid fungus, batrachochytrium dendrobatidis (bd), has been associated with amphibian declines around the world. however, bd-associated declines are more prominent in some areas, despite nearly global distribution of bd, suggesting other factors contribute to disease outbreaks. in a laboratory study, the authors examined the effects of 6 different isolates of bd in the p ...201425044296
amphibians acquire resistance to live and dead fungus overcoming fungal immunosuppression.emerging fungal pathogens pose a greater threat to biodiversity than any other parasitic group, causing declines of many taxa, including bats, corals, bees, snakes and amphibians. currently, there is little evidence that wild animals can acquire resistance to these pathogens. batrachochytrium dendrobatidis is a pathogenic fungus implicated in the recent global decline of amphibians. here we demonstrate that three species of amphibians can acquire behavioural or immunological resistance to b. den ...201425008531
temperature alone does not explain patterns of batrachochytrium dendrobatidis infections in the green frog lithobates clamitans.batrachochytrium dendrobatidis (bd) is an invasive, waterborne fungal pathogen that has caused significant declines and extinctions of amphibian species worldwide. temperature is a major factor impacting the growth and spread of bd, but little is known regarding the associated patterns in natural habitats. this study analyzed the temperature-associated trends, as correlated with season and microhabitat, of bd prevalence and infection intensity in green frogs lithobates clamitans in a temperate e ...201424991844
batrachochytrium dendrobatidis prevalence and haplotypes in domestic and imported pet amphibians in japan.the international trade in amphibians is believed to have increased the spread of batrachochytrium dendrobatidis (bd), the fungal pathogen responsible for chytridiomycosis, which has caused a rapid decline in amphibian populations worldwide. we surveyed amphibians imported into japan and those held in captivity for a long period or bred in japan to clarify the bd infection status. samples were taken from 820 individuals of 109 amphibian species between 2008 and 2011 and were analyzed by a nested ...201424991744
wetland characteristics influence disease risk for a threatened amphibian.identifying determinants of the probability and intensity of infections is important for understanding the epidemiology of wildlife diseases, and for managing their impact on threatened species. chytridiomycosis, caused by the fungal pathogen batrachochytrium dendrobatidis, has decimated populations of some amphibians. however, recent studies have identified important environmental constraints on the disease, related to the pathogen's physiological tolerances. in this study, we identified severa ...201424988766
interventions for reducing extinction risk in chytridiomycosis-threatened amphibians.wildlife diseases pose an increasing threat to biodiversity and are a major management challenge. a striking example of this threat is the emergence of chytridiomycosis. despite diagnosis of chytridiomycosis as an important driver of global amphibian 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 o ...201424975971
genomic studies of disease-outcome in host--pathogen dynamics.pathogens act as agents of evolutionary change in host populations, altering the host's allele frequencies and phenotypes through selection. the mechanisms underlying these adaptive changes depend on which defense strategy the host adopts upon infection. with increased anthropogenic change and loss of biodiversity, ecological impacts on adaptive processes may reduce the ability of hosts to evolve resistance, or to persist within their tolerance limits, thus increasing the capacity of pathogens t ...201424916476
tagging frogs with passive integrated transponders causes disruption of the cutaneous bacterial community and proliferation of opportunistic fungi.symbiotic bacterial communities play a key role in protecting amphibians from infectious diseases including chytridiomycosis, caused by the pathogenic fungus batrachochytrium dendrobatidis. events that lead to the disruption of the bacterial community may have implications for the susceptibility of amphibians to such diseases. amphibians are often marked both in the wild and in captivity for a variety of reasons, and although existing literature indicates that marking techniques have few negativ ...201424878599
amphibian skin may select for rare environmental microbes.host-microbe symbioses rely on the successful transmission or acquisition of symbionts in each new generation. amphibians host a diverse cutaneous microbiota, and many of these symbionts appear to be mutualistic and may limit infection by the chytrid fungus, batrachochytrium dendrobatidis, which has caused global amphibian population declines and extinctions in recent decades. using bar-coded 454 pyrosequencing of the 16s rrna gene, we addressed the question of symbiont transmission by examining ...201424858782
from all to (nearly) none: tracing adaptin evolution in fungi.the five adaptor protein (ap) complexes function in cargo-selection and coat-recruitment stages of vesicular transport in eukaryotic cells. much of what we know about ap complex function has come from experimental work using saccharomyces cerevisiae as a model. here, using a combination of comparative genomic and phylogenetic approaches we provide evolutionary context for the knowledge gained from this model system by searching the genomes of diverse fungi as well as a member of the sister group ...201424843829
fighting a losing battle: vigorous immune response countered by pathogen suppression of host defenses in the chytridiomycosis-susceptible frog atelopus zeteki.the emergence of the disease chytridiomycosis caused by the chytrid fungus batrachochytrium dendrobatidis (bd) has been implicated in dramatic global amphibian declines. although many species have undergone catastrophic declines and/or extinctions, others appear to be unaffected or persist at reduced frequencies after bd outbreaks. the reasons behind this variance in disease outcomes are poorly understood: differences in host immune responses have been proposed, yet previous studies suggest a la ...201424841130
assessing host extinction risk following exposure to batrachochytrium dendrobatidis.wildlife diseases are increasingly recognized as a major threat to biodiversity. chytridiomycosis is an emerging infectious disease of amphibians caused by the fungus batrachochytrium dendrobatidis (bd). using a mathematical model and simulations, we study its effects on a generic riparian host population with a tadpole and adult life stage. an analytical expression for the basic reproduction quotient, qo, of the pathogen is derived. by sampling the entire relevant parameter space, we perform a ...201424807247
susceptibility to the amphibian chytrid fungus varies with ontogeny in the direct-developing frog, eleutherodactylus coqui.age-related differences in susceptibility to infectious disease are known from a wide variety of plant and animal taxonomic groups. for example, the immature immune systems of young vertebrates, along with limited prior exposure to pathogens and behavioral factors, can place juveniles at greater risk of acquiring and succumbing to a pathogen. we studied the ontogenetic susceptibility of terrestrial direct-developing frogs (eleutherodactylus coqui) to the fungal pathogen, batrachochytrium dendrob ...201424807186
interacting symbionts and immunity in the amphibian skin mucosome predict disease risk and probiotic effectiveness.pathogenesis is strongly dependent on microbial context, but development of probiotic therapies has neglected the impact of ecological interactions. dynamics among microbial communities, host immune responses, and environmental conditions may alter the effect of probiotics in human and veterinary medicine, agriculture and aquaculture, and the proposed treatment of emerging wildlife and zoonotic diseases such as those occurring on amphibians or vectored by mosquitoes. here we use a holistic measu ...201424789229
evaluation of amphotericin b and chloramphenicol as alternative drugs for treatment of chytridiomycosis and their impacts on innate skin defenses.chytridiomycosis, an amphibian skin disease caused by the emerging fungal pathogen batrachochytrium dendrobatidis, has been implicated in catastrophic global amphibian declines. the result is an alarming decrease in amphibian diversity that is a great concern for the scientific community. clinical trials testing potential antifungal drugs are needed to identify alternative treatments for amphibians infected with this pathogen. in this study, we quantified the mics of chloramphenicol (800 μg/ml), ...201424771024
presence and prevalence of batrachochytrium dendrobatidis in commercial amphibians in mexico city.in mexico city, native and exotic amphibians are commonly sold through the pet trade. this study investigates the presence of batrachochytrium dendrobatidis (bd) in native amphibians being sold at two commercial markets and at a herpetarium in mexico city. a total of 238 individuals (6 genera and 12 species) were tested for bd using real-time polymerase chain reaction (pcr) analysis. there were 197 bd-positive individuals (prevalence 82%) from five species of amphibians. hyla eximia from the mar ...201425632670
host-specific thermal profiles affect fitness of a widespread pathogen.host behavior can interact with environmental context to influence outcomes of pathogen exposure and the impact of disease on species and populations. determining whether the thermal behaviors of individual species influence susceptibility to disease can help enhance our ability to explain and predict how and when disease outbreaks are likely to occur. the widespread disease chytridiomycosis (caused by the fungal pathogen batrachochytrium dendrobatidis, bd) often has species-specific impacts on ...201425505533
experimental evolution alters the rate and temporal pattern of population growth in batrachochytrium dendrobatidis, a lethal fungal pathogen of amphibians.virulence of infectious pathogens can be unstable and evolve rapidly depending on the evolutionary dynamics of the organism. experimental evolution can be used to characterize pathogen evolution, often with the underlying objective of understanding evolution of virulence. we used experimental evolution techniques (serial transfer experiments) to investigate differential growth and virulence of batrachochytrium dendrobatidis (bd), a fungal pathogen that causes amphibian chytridiomycosis. we teste ...201425478154
the interactive effects of chytrid fungus, pesticides, and exposure timing on gray treefrog (hyla versicolor) larvae.aquatic organisms are often exposed to a wide variety of perturbations in nature, including pathogens and chemical contaminants. despite the co-occurrence of these 2 stressors, few studies have examined the effects of chemical contaminants on host-pathogen dynamics. the authors tested the individual and combined effects on gray treefrog (hyla versicolor) tadpoles of 2 commonly used pesticides (roundup® and sevin®) and the pathogenic fungus batrachochytrium dendrobatidis (bd). a fully factorial d ...201424259231
dermocystid-chytrid coinfection in the neotropical frog hypsiboas pulchellus (anura: hylidae).we present gross and histologic evidence of coinfection in amphibians by fungal-like parasites of the order dermocystidia (amphibiocystidium sp.) and the fungus batrachochytrium dendrobatidis. the condition was observed in frogs hypsiboas pulchellus (hylidae) from uruguay in 2009 to 2012. this report is the first of dermocystids in neotropical amphibians since 1940.201424171571
drought reduces chytrid fungus (batrachochytrium dendrobatidis) infection intensity and mortality but not prevalence in adult crawfish frogs (lithobates areolatus).to fully understand the impacts of the chytrid fungus batrachochytrium dendrobatidis (bd) on amphibians it is necessary to examine the interactions between populations and their environment. ecologic variables can exacerbate or ameliorate bd prevalence and infection intensity, factors that are positively related when bd is acting on naive amphibian populations as an epidemic disease. in crawfish frogs (lithobates areolatus), a north american species with a complex life history, we have shown tha ...201424171560
nikkomycin z is an effective inhibitor of the chytrid fungus linked to global amphibian declines.fungal infections in humans, wildlife, and plants are a growing concern because of their devastating effects on human and ecosystem health. in recent years, populations of many amphibian species have declined, and some have become extinct due to chytridiomycosis caused by the fungal pathogen batrachochytrium dendrobatidis. for some endangered amphibian species, captive colonies are the best intermediate solution towards eventual reintroduction, and effective antifungal treatments are needed to c ...201424433676
a new species of psychrophrynella (anura: craugastoridae) from the cordillera real, department la paz, bolivia.we describe a new species of psychrophrynella from a single locality in the cordillera real, in the andes of department of la paz, bolivia. psychrophrynella teqta sp. nov. is highly variable in color pattern and differs from the species geographically closer mostly by presenting yellow or red blotches, usually absent in other species. in addition, the new species differs from all species in the genus because the males have a pulsed call. males of this species show parental care, and the high num ...201425543943
more than skin deep: functional genomic basis for resistance to amphibian chytridiomycosis.the amphibian-killing chytrid fungus batrachochytrium dendrobatidis (bd) is one of the most generalist pathogens known, capable of infecting hundreds of species globally and causing widespread population declines and extinctions. however, some host species are seemingly unaffected by bd, tolerating or clearing infections without clinical signs of disease. variation in host immune responses is commonly evoked for these resistant or tolerant species, yet to date, we have no direct comparison of am ...201425539724
pathogenic fungus batrachochytrium dendrobatidis in marbled water frog telmatobius marmoratus: first record from lake titicaca, bolivia.the pathogenic fungus batrachochytrium dendrobatidis (bd) has been associated with amphibian declines worldwide but has not been well-studied among critically endangered amphibian species in bolivia. we sampled free-living marbled water frogs telmatobius marmoratus (anura: leptodactylidae) from isla del sol, bolivia, for bd using skin swabs and quantitative polymerase chain reactions. we detected bd on 44% of t. marmoratus sampled. this is the first record of bd in amphibians from waters associa ...201425392045
chytridiomycosis risk among central european amphibians based on surveillance data.the czech republic hosts a surprisingly rich biodiversity of amphibians representing the majority of amphibian species present in all of central and eastern europe. surveillance data of batrachochytrium dendrobatidis (bd) collected during 2008 to 2012 were analysed for basic patterns of prevalence and infection intensity among species, age groups and localities. in addition, an investigation was made into possible data bias due to varying pcr inhibition. infection prevalence in the genus pelophy ...201425392037
the pathogen batrachochytrium dendrobatidis disturbs the frog skin microbiome during a natural epidemic and experimental infection.symbiotic microbial communities may interact with infectious pathogens sharing a common host. the microbiome may limit pathogen infection or, conversely, an invading pathogen can disturb the microbiome. documentation of such relationships during naturally occurring disease outbreaks is rare, and identifying causal links from field observations is difficult. this study documented the effects of an amphibian skin pathogen of global conservation concern [the chytrid fungus batrachochytrium dendroba ...201425385615
confronting inconsistencies in the amphibian-chytridiomycosis system: implications for disease management.chytridiomycosis, caused by the pathogenic fungus batrachochytrium dendrobatidis (bd), is one of the largest threats to wildlife and is putatively linked to the extirpation of numerous amphibians. despite over a decade of research on bd, conflicting results from a number of studies make it difficult to forecast where future epizootics will occur and how to manage this pathogen effectively. here, we emphasize how resolving these conflicts will advance bd management and amphibian conservation effo ...201424118903
interactive effects of competition and predator cues on immune responses of leopard frogs at metamorphosis.recent hypotheses suggest that immunosuppression, resulting from altered environmental conditions, may contribute to the increased incidence of amphibian disease around the world. antimicrobial peptides (amps) in amphibian skin are an important innate immune defense against fungal, viral and bacterial pathogens. their release is tightly coupled with release of the stress hormone noradrenaline (norepinephrine). during metamorphosis, amps may constitute the primary immune response in the skin of s ...201424115058
retrospective survey of museum specimens reveals historically widespread presence of batrachochytrium dendrobatidis in china.chytridiomycosis, caused by the chytrid fungus batrachochytrium dendrobatidis (bd), has been implicated in amphibian population declines worldwide. however, no amphibian declines or extinctions associated with bd have been reported in asia. to investigate the history of this pathogen in china, we examined 1,007 museum-preserved amphibian specimens of 80 species collected between 1933 and 2009. bd was detected in 60 individuals (6.0%), with the earliest case of bd infection occurring in one speci ...201424419667
microscopic aquatic predators strongly affect infection dynamics of a globally emerged pathogen.research on emerging infectious wildlife diseases has placed particular emphasis on host-derived barriers to infection and disease. this focus neglects important extrinsic determinants of the host/pathogen dynamic, where all barriers to infection should be considered when ascertaining the determinants of infectivity and pathogenicity of wildlife pathogens. those pathogens with free-living stages, such as fungi causing catastrophic wildlife declines on a global scale, must confront lengthy exposu ...201424374305
thermal physiology, disease, and amphibian declines on the eastern slopes of the andes.rising temperatures, a widespread consequence of climate change, have been implicated in enigmatic amphibian declines from habitats with little apparent human impact. the pathogenic fungus batrachochytrium dendrobatidis (bd), now widespread in neotropical mountains, may act in synergy with climate change causing collapse in thermally stressed hosts. we measured the thermal tolerance of frogs along a wide elevational gradient in the tropical andes, where frog populations have collapsed. we used t ...201424372791
effects of visible implanted elastomer marking on physiological traits of frogs.amphibians possess innate immune defences, including antimicrobial peptides and symbiotic bacterial communities, that can protect them from infectious diseases, including chytridiomycosis. on-going research is attempting to use amphibian symbiotic bacteria to develop probiotic treatments that can protect hosts from the causative agent of chytridiomycosis, the fungal pathogen batrachochytrium dendrobatidis. events that cause disruption of symbiotic bacterial communities or deplete peptide stores ...201427293663
first line of defence: the role of sloughing in the regulation of cutaneous microbes in frogs.amphibian populations worldwide are currently experiencing unprecedented declines due to the combined effects of emerging infectious disease and climate change. the skin is the first line of defence in preventing establishment of pathogens and associated infections. although amphibians undergo regular sloughing of the outer layer of the skin, the potential for regular sloughing to play a role in influencing cutaneous microbial populations and pathogens has been largely overlooked. in the present ...201427293633
assessing risk and guidance on monitoring of batrachochytrium dendrobatidis in europe through identification of taxonomic selectivity of infection.amphibians are globally threatened, but not all species are affected equally by different threatening processes. this is true for the threat posed by the chytridiomycete fungus (batrachochytrium dendrobatidis). we compiled a european data set for b. dendrobatidis to analyze the trends of infection in european amphibians. the risk of infection was not randomly distributed geographically or taxonomically across europe. within countries with different prevalence, infection was nonrandom in certain ...201424033675
linking manipulative experiments to field data to test the dilution effect.the dilution effect, the hypothesis that biodiversity reduces disease risk, has received support in many systems. however, few dilution effect studies have linked mechanistic experiments to field patterns to establish both causality and ecological relevance. we conducted a series of laboratory experiments and tested the dilution effect hypothesis in an amphibian-batrachochytrium dendrobatidis (bd) system and tested for consistency between our laboratory experiments and field patterns of amphibia ...201424289288
transition of chytrid fungus infection from mouthparts to hind limbs during amphibian metamorphosis.the chytrid fungus, batrachochytrium dendrobatidis (bd), is implicated in worldwide amphibian declines. bd has been shown to qualitatively transition from the mouthparts of tadpoles to the hindlimbs during metamorphosis, but we lack evidence of consistency in the timing of this transition across amphibian species. we also do not have predictive functions for the abundance of bd in mouthparts and limbs as tadpoles develop or for the relationship between keratin and bd abundance. hence, researcher ...201525384612
effects of pond salinization on survival rate of amphibian hosts infected with the chytrid fungus.the chytrid fungus batrachochytrium dendrobatidis has been implicated in the decline and extinction of amphibian populations worldwide, but management options are limited. recent studies show that sodium chloride (nacl) has fungicidal properties that reduce the mortality rates of infected hosts in captivity. we investigated whether similar results can be obtained by adding salt to water bodies in the field. we increased the salinity of 8 water bodies to 2 or 4 ppt and left an additional 4 water ...201525354647
correlates of virulence in a frog-killing fungal pathogen: evidence from a california amphibian decline.the fungal pathogen batrachochytrium dendrobatidis (bd) has caused declines and extinctions in amphibians worldwide, and there is increasing evidence that some strains of this pathogen are more virulent than others. while a number of putative virulence factors have been identified, few studies link these factors to specific epizootic events. we documented a dramatic decline in juvenile frogs in a bd-infected population of cascades frogs (rana cascadae) in the mountains of northern california and ...201525514536
trophic dynamics in an aquatic community: interactions among primary producers, grazers, and a pathogenic fungus.free-living stages of parasites are consumed by a variety of predators, which might have important consequences for predators, parasites, and hosts. for example, zooplankton prey on the infectious stage of the amphibian chytrid fungus, batrachochytrium dendrobatidis (bd), a pathogen responsible for amphibian population declines and extinctions worldwide. predation on parasites is predicted to influence community structure and function, and affect disease risk, but relatively few studies have exp ...201525432573
evidence of a salt refuge: chytrid infection loads are suppressed in hosts exposed to salt.with the incidence of emerging infectious diseases on the rise, it is becoming increasingly important to identify refuge areas that protect hosts from pathogens and therefore prevent population declines. for the chytrid fungus batrachochytrium dendrobatidis, temperature and humidity refuge areas for amphibian hosts exist but are difficult to manipulate. other environmental features that may affect the outcome of infection include water quality, drying regimes, abundance of alternate hosts and is ...201525416999
assessing the threat of amphibian chytrid fungus in the albertine rift: past, present and future.batrachochytrium dendrobatidis (bd), the cause of chytridiomycosis, is a pathogenic fungus that is found worldwide and is a major contributor to amphibian declines and extinctions. we report results of a comprehensive effort to assess the distribution and threat of bd in one of the earth's most important biodiversity hotspots, the albertine rift in central africa. in herpetological surveys conducted between 2010 and 2014, 1018 skin swabs from 17 amphibian genera in 39 sites across the albertine ...201526710251
salamanders increase their feeding activity when infected with the pathogenic chytrid fungus batrachochytrium dendrobatidis.immune function is a costly line of defense against parasitism. when infected with a parasite, hosts frequently lose mass due to these costs. however, some infected hosts (e.g. highly resistant individuals) can clear infections with seemingly little fitness losses, but few studies have tested how resistant hosts mitigate these costly immune defenses. we explored this topic using eastern red-backed salamanders plethodon cinereus and the fungal pathogen batrachochytrium dendrobatidis (bd). bd is g ...201526503775
'salamander plague' on britain's doorstep.chytridiomycosis can cause mass declines in amphibians, and the chytrid fungus batrachochytrium dendrobatidis is the classic cause of this disease. however, recently, a second strain of chytrid fungus has emerged in europe, resulting in major declines in fire salamanders. the zoological society of london (zsl) discussed this, and the implications for the uk, at a meeting in december in london. georgina mills reports.201525614547
asian strain of batrachochytrium dendrobatidis is widespread in the western ghats, india.we investigated the distribution of batrachochytrium dendrobatidis (bd) fungal infections in amphibians of the western ghats mountain range in india, based on data from 497 samples. eight individuals were positive, with genomic equivalents ranging from 2 to 785 zoospores. a single widespread bd strain identical to the haplotype endemic to asia was isolated. our findings suggest that chytridiomycosis is widespread among the endemic and threatened amphibians of the entire stretch of the western gh ...201525590776
itraconazole treatment reduces batrachochytrium dendrobatidis prevalence and increases overwinter field survival in juvenile cascades frogs.the global spread of the fungal pathogen batrachochytrium dendrobatidis (bd) has led to widespread extirpation of amphibian populations. during an intervention aimed at stabilizing at-risk populations, we treated wild-caught cascades frogs rana cascadae with the antifungal drug itraconazole. in fall 2012, we collected 60 recently metamorphosed r. cascadae from 1 of the 11 remnant populations in the cascades mountains (ca, usa). of these, 30 randomly selected frogs were treated with itraconazole ...201525590775
batrachochytrium dendrobatidis exposure effects on foraging efficiencies and body size in anuran tadpoles.chytridiomycosis, the amphibian disease caused by the pathogenic fungus batrachochytrium dendrobatidis (bd), is fatal to adults of many species. bd is largely sublethal to amphibian larvae; however, it is known to reduce larval (i.e. tadpole) growth rates, with possible long-term effects on population dynamics and fitness. we conducted an experiment to test how bd altered southern leopard frog lithobates sphenocephalus tadpole mouthpart damage, percentage of food ingested, and subsequent body si ...201525590774
batrachochytrium dendrobatidis in natural and farmed louisiana crayfish populations: prevalence and implications.the pathogenic chytrid fungus batrachochytrium dendrobatidis (bd) has been linked to global declines and extinctions of amphibians, making it one of the most devastating wildlife pathogens known. understanding the factors that affect disease dynamics in this system is critical for mitigating infection and protecting threatened species. crayfish are hosts of this pathogen and can transmit bd to amphibians. because they co-occur with susceptible amphibian communities, crayfish may be important alt ...201525590773
temperature variability and moisture synergistically interact to exacerbate an epizootic disease.climate change is altering global patterns of precipitation and temperature variability, with implications for parasitic diseases of humans and wildlife. a recent study confirmed predictions that increased temperature variability could exacerbate disease, because of lags in host acclimation following temperature shifts. however, the generality of these host acclimation effects and the potential for them to interact with other factors have yet to be tested. here, we report similar effects of host ...201525567647
carotenoids and amphibians: effects on life history and susceptibility to the infectious pathogen, batrachochytrium dendrobatidis.carotenoids are considered beneficial nutrients because they provide increased immune capacity. although carotenoid research has been conducted in many vertebrates, little research has been done in amphibians, a group that is experiencing global population declines from numerous causes, including disease. we raised two amphibian species through metamorphosis on three carotenoid diets to quantify the effects on life-history traits and post-metamorphic susceptibility to a fungal pathogen (batracho ...201527293690
delayed metamorphosis of amphibian larvae facilitates batrachochytrium dendrobatidis transmission and persistence.highly virulent pathogens that cause host population declines confront the risk of fade-out, but if pathogen transmission dynamics are age-structured, pathogens can persist. among other features of amphibian biology, variable larval developmental rates generate age-structured larval populations, which in theory can facilitate pathogen persistence. we investigated this possibility empirically in a population of salamandra salamandra in spain affected by batrachochytrium dendrobatidis (bd) at bree ...201526648101
seasonal and ontogenetic variation of skin microbial communities and relationships to natural disease dynamics in declining amphibians.recently, microbiologists have focused on characterizing the probiotic role of skin bacteria for amphibians threatened by the fungal disease chytridiomycosis. however, the specific characteristics of microbial diversity required to maintain health or trigger disease are still not well understood in natural populations. we hypothesized that seasonal and developmental transitions affecting susceptibility to chytridiomycosis could also alter the stability of microbial assemblages. to test our hypot ...201526587253
successful elimination of a lethal wildlife infectious disease in nature.methods to mitigate the impacts of emerging infectious diseases affecting wildlife are urgently needed to combat loss of biodiversity. however, the successful mitigation of wildlife pathogens in situ has rarely occurred. indeed, most strategies for combating wildlife diseases remain theoretical, despite the wealth of information available for combating infections in livestock and crops. here, we report the outcome of a 5-year effort to eliminate infection with batrachochytrium dendrobatidis affe ...201526582843
panamanian frog species host unique skin bacterial communities.vertebrates, including amphibians, host diverse symbiotic microbes that contribute to host disease resistance. globally, and especially in montane tropical systems, many amphibian species are threatened by a chytrid fungus, batrachochytrium dendrobatidis (bd), that causes a lethal skin disease. bd therefore may be a strong selective agent on the diversity and function of the microbial communities inhabiting amphibian skin. in panamá, amphibian population declines and the spread of bd have been t ...201526579083
amphibian chytrid fungus in madagascar neither shows widespread presence nor signs of certain establishment.the global spread of amphibian chytrid fungus (batrachochytrium dendrobatidis, bd) is associated with amphibian mass mortality, population decline, and extinction. over the past decade, concern has been expressed for the potential introduction of bd to madagascar, a global hotspot of amphibian biodiversity. following years without detection, widespread bd presence in madagascar has now been reported (bletz et al. 2015a), raising international conservation concern. before reacting to this finding ...201526465924
consistency of published results on the pathogen batrachochytrium dendrobatidis in madagascar: formal comment on kolby et al. rapid response to evaluate the presence of amphibian chytrid fungus (batrachochytrium dendrobatidis) and ranavirus in wild amphibian populations in madagascar. 201526465608
community structure and function of amphibian skin microbes: an experiment with bullfrogs exposed to a chytrid fungus.the vertebrate microbiome contributes to disease resistance, but few experiments have examined the link between microbiome community structure and disease resistance functions. chytridiomycosis, a major cause of amphibian population declines, is a skin disease caused by the fungus, batrachochytrium dendrobatidis (bd). in a factorial experiment, bullfrog skin microbiota was reduced with antibiotics, augmented with an anti-bd bacterial isolate (janthinobacterium lividum), or unmanipulated, and ind ...201526445500
current extinction rates of reptiles and amphibians.there is broad concern that a mass extinction of amphibians and reptiles is now underway. here i apply an extremely conservative bayesian method to estimate the number of recent amphibian and squamate extinctions in nine important tropical and subtropical regions. the data stem from a combination of museum collection databases and published site surveys. the method computes an extinction probability for each species by considering its sighting frequency and last sighting date. it infers hardly a ...201526438855
immunomodulatory metabolites released by the frog-killing fungus batrachochytrium dendrobatidis.batrachochytrium dendrobatidis is a fungal pathogen in the phylum chytridiomycota that causes the skin disease chytridiomycosis. chytridiomycosis is considered an emerging infectious disease linked to worldwide amphibian declines and extinctions. although amphibians have well-developed immune defenses, clearance of this pathogen from the skin is often impaired. previously, we showed that the adaptive immune system is involved in the control of the pathogen, but b. dendrobatidis releases factors ...201526371122
characterization of the skin microbiota in italian stream frogs (rana italica) infected and uninfected by a cutaneous parasitic disease.in human and wildlife populations, the natural microbiota plays an important role in health maintenance and the prevention of emerging infectious diseases. in amphibians, infectious diseases have been closely associated with population decline and extinction worldwide. skin symbiont communities have been suggested as one of the factors driving the different susceptibilities of amphibians to diseases. the activity of the skin microbiota of amphibians against fungal pathogens, such as batrachochyt ...201526370166
genomic correlates of virulence attenuation in the deadly amphibian chytrid fungus, batrachochytrium dendrobatidis.emerging infectious diseasespose a significant threat to global health, but predicting disease outcomes for particular species can be complicated when pathogen virulence varies across space, time, or hosts. the pathogenic chytrid fungus batrachochytrium dendrobatidis (bd) has caused worldwide declines in frog populations. not only do bd isolates from wild populations vary in virulence, but virulence shifts can occur over short timescales when bd is maintained in the laboratory. we leveraged chan ...201526333840
natural disturbance reduces disease risk in endangered rainforest frog populations.natural disturbances can drive disease dynamics in animal populations by altering the microclimates experienced by hosts and their pathogens. many pathogens are highly sensitive to temperature and moisture, and therefore small changes in habitat structure can alter the microclimate in ways that increase or decrease infection prevalence and intensity in host populations. here we show that a reduction of rainforest canopy cover caused by a severe tropical cyclone decreased the risk of endangered r ...201526294048
infection dynamics in frog populations with different histories of decline caused by a deadly disease.pathogens can drive host population dynamics. chytridiomycosis is a fungal disease of amphibians that is caused by the fungus batrachochytrium dendrobatidis (bd). this pathogen has caused declines and extinctions in some host species whereas other host species coexist with bd without suffering declines. in the early 1990s, bd extirpated populations of the endangered common mistfrog, litoria rheocola, at high-elevation sites, while populations of the species persisted at low-elevation sites. toda ...201526293680
dna extraction method affects the detection of a fungal pathogen in formalin-fixed specimens using qpcr.museum collections provide indispensable repositories for obtaining information about the historical presence of disease in wildlife populations. the pathogenic amphibian chytrid fungus batrachochytrium dendrobatidis (bd) has played a significant role in global amphibian declines, and examining preserved specimens for bd can improve our understanding of its emergence and spread. quantitative pcr (qpcr) enables bd detection with minimal disturbance to amphibian skin and is significantly more sens ...201526291624
patterns of batrachochytrium dendrobatidis transmission between tadpoles in a high-elevation rainforest stream in tropical australia.the highly virulent fungal pathogen batrachochytrium dendrobatidis (bd) poses a global threat to amphibian biodiversity. streams and other water bodies are central habitats in the ecology of the disease, particularly in rainforests where they may transport and transmit the pathogen and harbor infected tadpoles that serve as reservoir hosts. we conducted an experiment using larval green-eyed tree frogs litoria serrata in semi-natural streamside channels to test the hypotheses that (1) the fungus ...201526290506
the use of singleplex and nested pcr to detect batrachochytrium dendrobatidis in free-living frogs.many microorganisms are able to cause diseases in amphibians, and in the past few years one of the most reported has been batrachochytrium dendrobatidis. this fungus was first reported in brazil in 2005; following this, other reports were made in specimens deposited in museum collections, captive and free-living frogs. the aim of this study was to compare singleplex and nested-pcr techniques to detect b. dendrobatidis in free-living and apparently healthy adult frogs from the brazilian atlantic ...201526273273
geophysiology of wood frogs: landscape patterns of prevalence of disease and circulating hormone concentrations across the eastern range.one of the major challenges for conservation physiologists is to determine how current or future environmental conditions relate to the health of animals at the population level. in this study, we measured prevalence of disease, mean condition of the body, and mean resting levels of corticosterone and testosterone in a total of 28 populations across the years 2011 and 2012, and correlated these measures of health to climatic suitability of habitat, using estimates from a model of the ecological ...201526269462
effect of glucocorticoids on expression of cutaneous antimicrobial peptides in northern leopard frogs (lithobates pipiens).many species of frogs secrete cutaneous antimicrobial peptides that are capable of killing batrachochytrium dendrobatidis. some of these species are nonetheless susceptible to chytridiomycosis, suggesting that host factors causing dysregulation of this innate immune response may be important in pathogenesis. since stresses, such as from environmental perturbations, are a potential cause of such dysregulation, this study investigated the effect of glucocorticoid on cutaneous gene expression of th ...201526253169
treatment trial of clinically ill corroboree frogs with chytridiomycosis with two triazole antifungals and electrolyte therapy.chytridiomycosis caused by the pathogen batrachochytrium dendrobatidis is an important cause of amphibian declines globally, and is the worst pathogen on record for causing biodiversity 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 ...201526246159
correction: rapid response to evaluate the presence of amphibian chytrid fungus (batrachochytrium dendrobatidis) and ranavirus in wild amphibian populations in madagascar. 201526222617
differences in sensitivity to the fungal pathogen batrachochytrium dendrobatidis among amphibian populations.contributing to the worldwide biodiversity crisis are emerging infectious diseases, which can lead to extirpations and extinctions of hosts. for example, the infectious fungal pathogen batrachochytrium dendrobatidis (bd) is associated with worldwide amphibian population declines and extinctions. sensitivity to bd varies with species, season, and life stage. however, there is little information on whether sensitivity to bd differs among populations, which is essential for understanding bd-infecti ...201526219571
effects of pesticide mixtures on host-pathogen dynamics of the amphibian chytrid fungus.anthropogenic and natural stressors often interact to affect organisms. amphibian populations are undergoing unprecedented declines and extinctions with pesticides and emerging infectious diseases implicated as causal factors. although these factors often co-occur, their effects on amphibians are usually examined in isolation. we hypothesized that exposure of larval and metamorphic amphibians to ecologically relevant concentrations of pesticide mixtures would increase their post-metamorphic susc ...201526181492
most of the dominant members of amphibian skin bacterial communities can be readily cultured.currently, it is estimated that only 0.001% to 15% of bacteria in any given system can be cultured by use of commonly used techniques and media, yet culturing is critically important for investigations of bacterial function. despite this situation, few studies have attempted to link culture-dependent and culture-independent data for a single system to better understand which members of the microbial community are readily cultured. in amphibians, some cutaneous bacterial symbionts can inhibit est ...201526162880
seasonal variation in population abundance and chytrid infection in stream-dwelling frogs of the brazilian atlantic forest.enigmatic amphibian declines were first reported in southern and southeastern brazil in the late 1980s and included several species of stream-dwelling anurans (families hylodidae and cycloramphidae). at that time, we were unaware of the amphibian-killing fungus batrachochytrium dendrobatidis (bd); therefore, pollution, habitat loss, fragmentation and unusual climatic events were hypothesized as primary causes of these declines. we now know that multiple lineages of bd have infected amphibians of ...201526161777
marginal bayesian nonparametric model for time to disease arrival of threatened amphibian populations.the global emergence of batrachochytrium dendrobatidis (bd) has caused the extinction of hundreds of amphibian species worldwide. it has become increasingly important to be able to precisely predict time to bd arrival in a population. the data analyzed herein present a unique challenge in terms of modeling because there is a strong spatial component to bd arrival time and the traditional proportional hazards assumption is grossly violated. to address these concerns, we develop a novel marginal b ...201526148536
linking genetic and environmental factors in amphibian disease risk.a central question in evolutionary biology is how interactions between organisms and the environment shape genetic differentiation. the pathogen batrachochytrium dendrobatidis (bd) has caused variable population declines in the lowland leopard frog (lithobates yavapaiensis); thus, disease has potentially shaped, or been shaped by, host genetic diversity. environmental factors can also influence both amphibian immunity and bd virulence, confounding our ability to assess the genetic effects on dis ...201526136822
successful treatment of batrachochytrium salamandrivorans infections in salamanders requires synergy between voriconazole, polymyxin e and temperature.chytridiomycosis caused by the chytrid fungus batrachochytrium salamandrivorans (bsal) poses a serious threat to urodelan diversity worldwide. antimycotic treatment of this disease using protocols developed for the related fungus batrachochytrium dendrobatidis (bd), results in therapeutic failure. here, we reveal that this therapeutic failure is partly due to different minimum inhibitory concentrations (mics) of antimycotics against bsal and bd. in vitro growth inhibition of bsal occurs after ex ...201526123899
a de novo assembly of the common frog (rana temporaria) transcriptome and comparison of transcription following exposure to ranavirus and batrachochytrium dendrobatidis.amphibians are experiencing global declines and extinctions, with infectious diseases representing a major factor. in this study we examined the transcriptional response of metamorphic hosts (common frog, rana temporaria) to the two most important amphibian pathogens: batrachochytrium dendrobatidis (bd) and ranavirus. we found strong up-regulation of a gene involved in the adaptive immune response (ap4s1) at four days post-exposure to both pathogens. we detected a significant transcriptional res ...201526111016
larval environment alters amphibian immune defenses differentially across life stages and populations.recent global declines, extirpations and extinctions of wildlife caused by newly emergent diseases highlight the need to improve our knowledge of common environmental factors that affect the strength of immune defense traits. to achieve this goal, we examined the influence of acidification and shading of the larval environment on amphibian skin-associated innate immune defense traits, pre and post-metamorphosis, across two populations of american bullfrogs (rana catesbeiana), a species known for ...201526107644
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