CHLORAMPHENICOL WITH FLUID AND ELECTROLYTE THERAPY CURES TERMINALLY ILL GREEN TREE FROGS (<i>LITORIA CAERULEA</i>) WITH CHYTRIDIOMYCOSIS

Young, Sam; Speare, Rick; Berger, Lee; Skerratt, Lee F.

doi:10.1638/2011-0231.1

Cited by 38 publications

(45 citation statements)

References 33 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: 61%

“…This susceptibility, and the rapid deaths observed at the Kihansi facility, support the sharp population declines of wild toads observed in 2003 and their proposed chytridiomycosis-mediated extinction (Weldon & du Preez 2004, Channing et al 2006. Chloramphenicol and itraconazole have been successfully used in treating amphibian chytridiomycosis (For zán et al 2008, Tamukai et al 2011, Young et al 2012 man & Pessier 2013). In our study, toads were initially treated using chloramphenicol before itraconazole was made available.…”

Section: Discussionmentioning

confidence: 77%

“…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: 61%

Section: Discussionmentioning

confidence: 77%

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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“…Only one study to date 20 has successfully treated terminally ill amphibians, and the treatment involved an aggressive combination of electrolyte therapy and chemotherapy. Successful treatment options for terminally ill animals are needed, especially for critically endangered animals in captive colonies where protection of every individual is essential for conservation of the species.…”

confidence: 99%

Reduced Itraconazole Concentration and Durations Are Successful in Treating <em>Batrachochytrium dendrobatidis</em> Infection in Amphibians

Brannelly

2014

JoVE

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Amphibians are experiencing the greatest decline of any vertebrate class and a leading cause of these declines is a fungal pathogen, Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis. Captive assurance colonies are important worldwide for threatened amphibian species and may be the only lifeline for those in critical threat of extinction. Maintaining disease free colonies is a priority of captive managers, yet safe and effective treatments for all species and across life stages have not been identified. The most widely used chemotherapeutic treatment is itraconazole, although the dosage commonly used can be harmful to some individuals and species. We performed a clinical treatment trial to assess whether a lower and safer but effective dose of itraconazole could be found to cure Bd infections. We found that by reducing the treatment concentration from 0.01-0.0025% and reducing the treatment duration from 11-6 days of 5 min baths, frogs could be cured of Bd infection with fewer side effects and less treatment-associated mortality. Video LinkThe video component of this article can be found at

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“…If a frog demonstrated advanced clinical signs, including slow righting reflex and body mass loss, it was removed from the experiment and treated with 20mg L -1 topical chloramphenicol, placed in an incubator at 28˚C for up to 14 days (Young et al 2012), and given oral 12% Whitaker-Wright solution (242 mMol l -1 NaCl, 4.3 mMol l -1 MgSO 4 7H 2 0, 2.85 mMol l -1 CaCl 2 , 2.85 mMol l -1 KCl) daily to help correct electrolyte imbalance ).…”

Section: Measuring Infection Loadmentioning

confidence: 99%

Interactions between amphibian skin sloughing and a cutaneous fungal disease: infection progression, immune defence, and phylogenetic patterns

Ohmer¹

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Worldwide, there has been an unprecedented rise in emerging infectious diseases of wildlife, and this has contributed to a widespread biodiversity crisis. Amphibian populations, in particular, are threatened by the fungal pathogen Batrachochytrium dendrobatidis (Bd), which in post-metamorphic animals only infects the skin, and causes the potentially lethal disease chytridiomycosis. Amphibians regularly slough their skin, and in doing so remove many skinassociated microbes. Thus, skin sloughing may play an important role in the pathogenesis of chytridiomycosis. To investigate this association, the influence of Bd infection on amphibian skin sloughing, and the role of sloughing in regulating infection, was examined. Furthermore, to better understand the variation in skin sloughing rates across species and ecological groups, and make inferences about the role of this process in susceptibility to this fungal disease, amphibian skin structure and function was investigated within a phylogenetic context. To determine the relationship between skin sloughing and disease progression (chapter 2), adult green tree frogs (Litoria caerulea) were exposed to an Australian Bd strain, and sloughing rates and infection load were monitored on a naturalistic cycling temperature regime (15 -23˚C).Sloughing rates were determined by filming frogs and infection intensity was monitored before and after sloughing with conventional swabbing and quantitative PCR. Sloughing rate was found to increase with Bd infection load in infected frogs, but sloughing itself did not affect Bd load on the ventral skin surface. Although a faster sloughing rate might be considered advantageous for Bdinfected animals, it does not appear to curb the progression of disease in susceptible species. In fact, sloughing may actually contribute to the loss of physiological homeostasis seen in terminally ill frogs by further inhibiting water and electrolyte transport across the skin.In some species less susceptible to chytridiomycosis, it has been demonstrated that Bd growth remains epibiotic, without penetrating the underlying epidermal layers. Therefore, sloughing may more effectively remove Bd zoospores in less susceptible species (chapter 3). To test this hypothesis, five Australian frog species, Lit. caerulea, Platyplectrum ornatum, Lechriodus fletcheri, Limnodynastes peronii, and Lim. tasmaniensis, were exposed to an Australian Bd strain, and their sloughing rates and infection loads monitored over time. Utilising an improved methodology to remove any artefacts from the swabbing itself, sloughing was found to reduce Bd load on the ventral skin surface, in all five species, despite wide ranging variation in susceptibility to Bd infection and subsequent disease. In less susceptible species, sloughing reduced Bd load up to 100%, leading to infection clearance. However, the drop in Bd load was only temporary in susceptible species, potentially due to the invasive growth of Bd in skin layers underlying the ii stratum corneum in these species. If less suscept...

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CHLORAMPHENICOL WITH FLUID AND ELECTROLYTE THERAPY CURES TERMINALLY ILL GREEN TREE FROGS (LITORIA CAERULEA) WITH CHYTRIDIOMYCOSIS

Cited by 38 publications

References 33 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)

Reduced Itraconazole Concentration and Durations Are Successful in Treating <em>Batrachochytrium dendrobatidis</em> Infection in Amphibians

Interactions between amphibian skin sloughing and a cutaneous fungal disease: infection progression, immune defence, and phylogenetic patterns

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