Pathogenesis of Chytridiomycosis, a Cause of Catastrophic Amphibian Declines

  title={Pathogenesis of Chytridiomycosis, a Cause of Catastrophic Amphibian Declines},
  author={Jamie Voyles and Sam Young and Lee R. Berger and Craig R. Campbell and Wyatt F. Voyles and Anuwat Dinudom and David Cook and Rebecca J. Webb and Ross A. Alford and Lee F. Skerratt and Richard Speare},
  pages={582 - 585}
Croaking Frogs The global amphibian decline has been attributed, among other causes, to an amphibian 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. A fungal disease that is associated with… 

Emerging amphibian diseases in Queensland and host immune response to disease

It is suggested that B. dendrobatidis kills amphibians by disrupting normal epidermal functioning, leading to osmotic imbalance through loss of electrolytes, which is fundamental to understanding the host– pathogen relationship and thus the population declines attributed to B.

Does Chytridiomycosis Disrupt Amphibian Skin Function?

Evidence of inhibited rehydration in individuals exhibiting clinical signs of chytridiomycosis is provided, however, aclinical chy TRD does not severely affect amphibian skin function, and frogs that survive infection by Bd, even if they remain infected, may suffer no significant impairment in their physiological responses.

Pathophysiology in Mountain Yellow-Legged Frogs (Rana muscosa) during a Chytridiomycosis Outbreak

It is found that pathogen load is associated with disruptions in fluid and electrolyte balance, yet is not associated with fluctuations acid-base balance, which enhances knowledge of the pathophysiology of this disease and indicates that disease development is consistent across multiple species and in both laboratory and natural conditions.

Epidemiology of chytridiomycosis in rainforest stream tadpoles

The relationships between infection intensity, prevalence, tooth loss and body condition indicate that these tadpoles have a measure of tolerance or increased resistance, which may be a result of strong selection pressure exerted by chytridiomycosis, which is critical to properly understand and mitigate species declines and prevent extinction.

Enzootic and epizootic dynamics of the chytrid fungal pathogen of amphibians

Results suggest that host persistence versus extinction does not require differences in host susceptibility, pathogen virulence, or environmental conditions, and may be just epidemic and endemic population dynamics of the same host–pathogen system.

Immunological Aspects of Chytridiomycosis

An integrated synthesis of amphibian post-metamorphic immunological responses and the corresponding outcomes of infection with Batrachochytrium dendrobatidis is presented, focusing on recent developments within the field and highlighting future directions.

A pathogenic skin fungus and sloughing exacerbate cutaneous water loss in amphibians

Examining how skin sloughing, body size and Bd infection interact to influence water loss rates in five Australian frog species found that dehydration stress may be a significant factor contributing to the morbidity of severely Bd infected anurans, a symptom that is then exacerbated by an increased rate ofSloughing.

Do Frogs Infected with Batrachochytrium dendrobatidis Avoid Water While Sloughing?

This study provides insight into the behavioral effects of chytridiomycosis, demonstrating that Bd infection can induce behaviors that might alter disease progression and could contribute to intra- and interspecific differences in pathophysiology.

Population and disease dynamics of the amphibian chytrid fungus in the stream-associated frog Litoria rheocola

There was a significant interaction between the effects of season and site type on the prevalence of Bd in tadpoles, and infection persisted throughout summer and winter in populations at high elevations.

Host Stress Response Is Important for the Pathogenesis of the Deadly Amphibian Disease, Chytridiomycosis, in Litoria caerulea

Elevated baseline corticosterone is associated with chytridiomycosis and correlates with some of the deleterious effects observed during disease development, which is suggested to be a biochemical connection between these disparate effects.



Electrolyte depletion and osmotic imbalance in amphibians with chytridiomycosis.

It is suggested that B. dendrobatidis kills amphibians by disrupting normal epidermal functioning, leading to osmotic imbalance through loss of electrolytes, which is fundamental to understanding the host-pathogen relationship and thus the population declines attributed to B. Dendrobatides.

Inconclusiveness of Chytridiomycosis as the Agent in Widespread Frog Declines

The case has not yet been made conclusively that the chytrid fungus Batrachochytrium dendrobatidis is the primary agent responsible for widespread declines in amphibian populations, particularly rainforest frog populations in Australia and Central America, but it remains unclear whether the pathogen is novel where declines have occurred.

Resistance to chytridiomycosis varies among amphibian species and is correlated with skin peptide defenses

Differences in susceptibility to chytridiomycosis among four Australian species after experimental infection with B. dendrobatidis are demonstrated, and it is observed that circulating granulocyte, but not lymphocyte, counts differed between infected and uninfected Lit.

Spread of Chytridiomycosis Has Caused the Rapid Global Decline and Extinction of Frogs

It is important for the scientific community and conservation agencies to recognize and manage the threat of chytridiomycosis to remaining species of frogs, especially those that are naive to the pathogen.

Ecology of Chytridiomycosis in Rainforest Stream Frog Assemblages of Tropical Queensland

The data indicate that at the landscape level, environmental conditions have strong effects on host-pathogen dynamics and interact with species-specific behavior or immune function and may be important underlying determinants of chytridiomycosis epizootics and emergence.

Persistence of the emerging pathogen Batrachochytrium dendrobatidis outside the amphibian host greatly increases the probability of host extinction

To investigate the effect of a free-living stage of B. dendrobatidis on host population dynamics, a mathematical model was developed to describe the introduction of chytridiomycosis into a breeding population of Bufo bufo, parametrized from laboratory infection and transmission experiments.

Chytridiomycosis causes amphibian mortality associated with population declines in the rain forests of Australia and Central America.

  • L. BergerR. Speare H. Parkes
  • Environmental Science
    Proceedings of the National Academy of Sciences of the United States of America
  • 1998
Experimental data support the conclusion that cutaneous chytridiomycosis is a fatal disease of anurans, and it is hypothesize that it is the proximate cause of these recent amphibian declines.

Distribution of Batrachochytrium dendrobatidis and pathology in the skin of green tree frogs Litoria caerulea with severe chytridiomycosis.

The number of sporangia was highly variable and this appeared to be related to the stage in the cycle of sloughing, and other pathological changes such as hyperkeratosis and congestion occurred much more frequently on ventral surfaces.

Global gene expression profiles for life stages of the deadly amphibian pathogen Batrachochytrium dendrobatidis

Comparison of patterns of global gene expression in controlled laboratory conditions for the two phases of the life cycle of Batrachochytrium dendrobatidis finds zoospores to be transcriptionally less complex than sporangia, and several transcripts more abundant in zoospore provide clues about how this motile life stage interacts with its environment.

The Decline of the Sharp-Snouted Day Frog (Taudactylus acutirostris): The First Documented Case of Extinction by Infection in a Free-Ranging Wildlife Species?

It is proposed that the recent extinction of the sharp-snouted day frog Taudactylus acutirostris is the first case of extinction by infection of a free-ranging wildlife species where disease acted as both the proximate and ultimate cause of extinction.