Sensitivity of histology for the detection of the amphibian chytrid fungus Batrachochytrium dendrobatidis

Histology is often underappreciated for the detection of the amphibian pathogenic fungus Batrachochytrium dendrobatidis, the cause of the potentially lethal skin disease chytridiomycosis. We evaluated the sensitivity of histology to detect chytrids in 20 wild specimens of 2 frog species from Uruguay that were clinically normal, but confirmed by PCR to be infected by B. dendrobatidis. We detected maturing and sporulated sporangia in 15 of 20 (75%) frogs, which is more sensitive than previously reported for histology. The effort needed to identify chytrids in histologic skin sections of Physalaemus henselii and Pleurodema bibroni required examination of 3.2 and 8.7 mm of skin sections for each frog species, respectively.

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Bad neighbours? Dynamics of amphibian chytrid fungus Batrachochytrium dendrobatidis infection in three co-occurring frog species of southern Sydney

Diseases of Aquatic Organisms ◽

10.3354/dao03557 ◽

2020 ◽

Author(s):

J Crawford-Ash ◽

JJL Rowley

Keyword(s):

Batrachochytrium Dendrobatidis ◽

Chytrid Fungus ◽

Frog Species ◽

Amphibian Chytrid Fungus

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DISTRIBUTION, DIET, AND PREVALENCE OF AMPHIBIAN CHYTRID FUNGUS IN NON-NATIVE AMERICAN BULLFROGS (LITHOBATES CATESBEIANUS) AT THE VALENTINE NATIONAL WILDLIFE REFUGE, NEBRASKA, USA

Journal of North American Herpetology ◽

10.17161/jnah.vi1.11900 ◽

2014 ◽

pp. 81-86

Author(s):

Alyx R. Lingenfelter ◽

Keith Geluso ◽

Melvin P. Nenneman ◽

Brian C. Peterson ◽

Jacob L. Kerby

Keyword(s):

Native American ◽

Disease Transmission ◽

Batrachochytrium Dendrobatidis ◽

Interspecific Interactions ◽

Pathogenic Fungus ◽

Chytrid Fungus ◽

National Wildlife Refuge ◽

Wildlife Refuge ◽

Lithobates Catesbeianus ◽

Amphibian Chytrid Fungus

American Bullfrogs (Lithobates catesbeianus) have been widely introduced beyond their native range in North America and can negatively affect organisms in wetland environments via a suite of mechanisms including interspecific interactions and disease transmission. Bullfrogs were introduced to the Valentine National Wildlife Refuge in the Sandhill Region of Nebraska, USA, yet little is known regarding their distribution, abundance, and potential effects on other vertebrates in the Refuge. Surveys in 1991-1992 documented bullfrogs in only one lake by the Refuge headquarters, and anecdotal historical observations indicated that bullfrogs were present primarily in lakes open to public fishing. In 2012, we determined the distribution of bullfrogs across the Refuge, examined their diets, and sampled them for the occurrence of the pathogenic fungus, Batrachochytrium dendrobatidis. We documented that bullfrogs were almost ubiquitous across the Refuge lakes and wetlands. From diet analyses, we observed that adult bullfrogs consumed several vertebrate species on the Refuge including: a Blanding’s Turtle (Emydoidea blandingii), small bullfrogs, an unidentifiable frog species, and numerous invertebrates, including crayfish. The amphibian chytrid fungus was prevalent on the refuge with 73.7% of bullfrogs testing positive for the fungus in early June and 6.3% in late June-July. Preliminary data indicate that bullfrogs likely have already affected interspecific interactions with native amphibians via predation, competition, and/or disease transmission. Bullfrogs likely cannot be eradicated from the Refuge, but expanding the season of harvest of bullfrogs might reduce their abundance, which may benefit native amphibians and reptiles.

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Is overwintering mortality driving enigmatic declines? Evaluating the impacts of trematodes and the amphibian chytrid fungus on an anuran from hatching through overwintering

PLoS ONE ◽

10.1371/journal.pone.0262561 ◽

2022 ◽

Vol 17 (1) ◽

pp. e0262561

Author(s):

Olivia Wetsch ◽

Miranda Strasburg ◽

Jessica McQuigg ◽

Michelle D. Boone

Keyword(s):

Batrachochytrium Dendrobatidis ◽

Species Conservation ◽

Emerging Infectious Diseases ◽

The Novel ◽

Chytrid Fungus ◽

Growth And Survival ◽

Critical Life Events ◽

Overwintering Mortality ◽

Amphibian Chytrid Fungus

Emerging infectious diseases are increasing globally and are an additional challenge to species dealing with native parasites and pathogens. Therefore, understanding the combined effects of infectious agents on hosts is important for species’ conservation and population management. Amphibians are hosts to many parasites and pathogens, including endemic trematode flatworms (e.g., Echinostoma spp.) and the novel pathogenic amphibian chytrid fungus (Batrachochytrium dendrobatidis [Bd]). Our study examined how exposure to trematodes during larval development influenced the consequences of Bd pathogen exposure through critical life events. We found that prior exposure to trematode parasites negatively impacted metamorphosis but did not influence the effect of Bd infection on terrestrial growth and survival. Bd infection alone, however, resulted in significant mortality during overwintering—an annual occurrence for most temperate amphibians. The results of our study indicated overwintering mortality from Bd could provide an explanation for enigmatic declines and highlights the importance of examining the long-term consequences of novel parasite exposure.

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