Pathogenesis, Diagnosis, and Treatment of Amphibian Chytridiomycosis

Baitchman, Eric; Pessier, Allan P.

doi:10.1016/j.cvex.2013.05.009

Cited by 34 publications

(24 citation statements)

References 56 publications

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“…It is possible that chloramphenicol would have been effective if the drug had been administered for a longer duration. Chloramphenicol has been shown to be effective against chytridiomycosis when administered for at least 2 wk (Young et al 2012, Baitchman & Pessier 2013. However, treatment of KST with itraconazole rapidly reduced mortalities, supporting previous observations of the high efficacy of this drug against chytridiomycosis in amphibians (Forzán et al 2008, Tamukai et al 2011, Baitchman & Pessier 2013.…”

Section: Discussionsupporting

confidence: 58%

“…However, peak mortalities of KST were ob served between 1 and 72 h following treatment. The concentration of itraconazole used in this study is commonly administered (Baitchman & Pessier 2013) but was 4 times higher than the concentrations recommended by Brannelly et al (2012), and this may have contributed to drug-induced mortalities. Previous surveillance of Bd in the Udzungwa Mountains found widespread distribution of Bd in amphibian populations (Moyer & Weldon 2006).…”

Section: Discussionmentioning

confidence: 80%

“…In addition, Bd produces toxic factors that inhibit protective host immune responses (Fites et al 2013) and cause slower rehydration across the skin (Carver et al 2010). In captivity, chytridiomycosis in amphibians can be treated with either chloramphenicol or itraconazole, the latter being the drug of choice (Forzán et al 2008, Bishop et al 2009, Young et al 2012, Baitchman & Pessier 2013. A diagnostic polymerase chain reaction (PCR) assay for sensitive and specific detection of Bd has been developed using primers that amplify a region of the 5.8S ribosomal RNA gene and the flanking internal transcribed spacer regions (ITS1 and ITS2; Annis et al 2004).…”

Section: Introductionmentioning

confidence: 99%

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Batrachochytrium dendrobatidis detected in Kihansi spray toads at a captive breeding facility (Kihansi, Tanzania)

Makange

Kulaya²,

Biseko³

et al. 2014

Dis. Aquat. Org.

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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 especially evident on the toe pads. Treatment of toads with itraconazole rapidly reduced mortalities. Dead toads (n = 49) were collected and used to perform Bd-specific polymerase chain reaction and subsequent nucleotide sequencing. All toads collected at the facility were positive for Bd. The obtained Bd 5.8S rRNA gene and flanking internal transcribed spacer regions (ITS1 and ITS2) were not 100% identical to any other Bd sequences in GenBank, but closely resembled isolates from Ecuador, Japan, USA, Brazil, Korea, and South Africa. To our knowledge, this is the first study reporting molecular characteristics of Bd isolated from the Udzungwa Mountains. Strict biosecurity measures at the breeding facility and in Kihansi spray wetlands where toads have been reintroduced have been implemented. Further studies on Bd epidemiology in the Udzungwa Mountains are recommended in order to understand its origin, prevalence, and molecular characteristics in wild amphibian populations. This will be important for conservation of several endemic amphibian species in the Udzungwa Mountains, which are part of the Eastern Arc Mountains, a global biodiversity hotspot.

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Section: Discussionsupporting

confidence: 58%

Section: Discussionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

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Batrachochytrium dendrobatidis detected in Kihansi spray toads at a captive breeding facility (Kihansi, Tanzania)

Makange

Kulaya²,

Biseko³

et al. 2014

Dis. Aquat. Org.

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“…Specifically, the treatment involves exposing frogs to a 0.01% (100 g/ml) itraconazole (Sporanox) bath for 10 min daily for 10 days (24). This treatment can lead to depigmentation in tadpoles (25) and toxic effects in some adult amphibians (26), although recent studies have suggested that a reduced dose and treatment length may still be effective (27,28).…”

mentioning

confidence: 99%

Evaluation of Amphotericin B and Chloramphenicol as Alternative Drugs for Treatment of Chytridiomycosis and Their Impacts on Innate Skin Defenses

Holden

Ebert

Canning

et al. 2014

Appl Environ Microbiol

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c 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 g/ml), amphotericin B (0.8 to 1.6 g/ml), and itraconazole (Sporanox) (20 ng/ml) against B. dendrobatidis. Both chloramphenicol and amphotericin B significantly reduced B. dendrobatidis infection in naturally infected southern leopard frogs (Rana [Lithobates] sphenocephala), although neither drug was capable of complete fungal clearance. Long-term exposure of R. sphenocephala to these drugs did not inhibit antimicrobial peptide (AMP) synthesis, indicating that neither drug is detrimental to this important innate skin defense. However, we observed that chloramphenicol, but not amphotericin B or itraconazole, inhibited the growth of multiple R. sphenocephala skin bacterial isolates in vitro at concentrations below the MIC against B. dendrobatidis. These results indicate that treatment with chloramphenicol might dramatically alter the protective natural skin microbiome when used as an antifungal agent. This study represents the first examination of the effects of alternative antifungal drug treatments on amphibian innate skin defenses, a crucial step to validating these treatments for practical applications.

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“…Over time, much was learned about husbandry (Gagliardo et al, 2008), treatment of chytridiomycosis (Baitchman & Pessier, 2013) and specific causes of mortality including nutritional issues, polycystic kidney lesions, parasites, metabolic bone disease (Pessier et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Evaluating the probability of avoiding disease‐related extinctions of Panamanian amphibians through captive breeding programs

et al. 2016

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Amphibians around the world are declining from threats that cannot currently be mitigated, making it impossible to safeguard some species in their natural habitats. Amphibians in the mountainous neotropics are one example where severe diseaserelated declines prompted calls for the establishment of captive assurance colonies to avoid extinctions. We surveyed experts in Panamanian amphibians to determine the probability of avoiding chytridiomycosis-related extinctions using captive breeding programs. We ranked Panamanian amphibian species by perceived susceptibility to chytridiomycosis, then calculated the likelihood of avoiding extinction as the product of three probabilities, which include (1) finding sufficient founder animals, (2) successfully breeding these species in captivity and (3) becoming extinct in the wild. The likelihood of finding enough animals to create a captive founding population was low for many rare species, especially for salamanders and caecilians. It was also low for frogs which were once regularly encountered, but have already disappeared including Atelopus chiriquiensis, Craugastor emcelae, C. obesus, C. punctariolus, C. rhyacobatrachus, Ecnomiohyla rabborum, Isthmohyla calypsa and Oophaga speciosa. Our results indicate that captive breeding could improve the odds of avoiding extinction for species that have severely declined or are likely to decline due to chytridiomycosis including Atelopus certus, A.

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Pathogenesis, Diagnosis, and Treatment of Amphibian Chytridiomycosis

Cited by 34 publications

References 56 publications

Batrachochytrium dendrobatidis detected in Kihansi spray toads at a captive breeding facility (Kihansi, Tanzania)

Batrachochytrium dendrobatidis detected in Kihansi spray toads at a captive breeding facility (Kihansi, Tanzania)

Evaluation of Amphotericin B and Chloramphenicol as Alternative Drugs for Treatment of Chytridiomycosis and Their Impacts on Innate Skin Defenses

Evaluating the probability of avoiding disease‐related extinctions of Panamanian amphibians through captive breeding programs

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