Elimination of the amphibian chytrid fungus Batrachochytrium dendrobatidis by Archey’s frog Leiopelma archeyi

Abstract

Archey's frog Leiopelma archeyi is a critically endangered New Zealand endemic species. The discovery of the emerging infectious disease, chytridiomycosis, in wild populations of this frog raised concern that this disease may drive the species to extinction. Twelve wild-caught Archey's frogs naturally infected with the amphibian chytrid fungus Batrachochytrium dendrobatidis were monitored in captivity by observing clinical signs, measuring weight gain, and performing repeated PCR tests. Eight frogs were treated with topical chloramphenicol, without PCR results being available, for B. dendrobatidis at the day of entry of the frog into the trial. Eleven of the 12 frogs (92%) cleared their infection within 3 mo of capture, even though they were held at 15°C and in high humidity, conditions that are ideal for the survival and propagation of B. dendrobatidis. B. dendrobatidis in the remaining frog tested positive for the fungus was eliminated after treatment with topical chloramphenicol. None of the 8 frogs exposed to chloramphenicol showed any acute adverse reactions. Archey's frog appears to have a low level of susceptibility to the clinical effects of chytridiomycosis. Individual frogs can eliminate B. dendrobatidis and Archey's frog can apparently be treated with topical chloramphenicol with no acute adverse reactions. However, the small number of specimens treated here requires that more extensive testing be done to confirm the safety of chloramphenicol. The significance of the amphibian chytrid fungus for wild populations of Archey's frog needs to be determined by a longitudinal study in an infected wild population to correlate the presence of B. dendrobatidis in individual frogs. Such a study should occur over a period of at least 3 yr with clinical assessment and monitoring of survival, growth and body condition parameters.

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

“…It has been speculated that chloramphenicol therapy causes apoptosis in the skin, killing intracellular sporangia, although the exact mechanism of action is unknown. Although no clinical trial has been conducted, and therefore dose and treatment time have not been assessed, current treatment protocols typically require submersion for two to four weeks 10,11 , making this treatment impractical for terrestrial amphibians. Chloramphenicol has also been restricted in some countries for veterinary use because human exposure has been associated with a rare form of aplastic anemia 12 .…”

Eradication of the chytrid fungus Batrachochytrium dendrobatidis in the Japanese giant salamander Andrias japonicus

“…A number of Bd eradication initiatives have been proposed (Parker et al 2002, Woodhams et al 2003, Forzán et al 2008, Bishop et al 2009, Garner et al 2009, Berger et al 2010, Martel et al 2011. One method exploits the low heat resistance of Bd (Woodhams et al 2003), whereas others using formalin and malachite green have also been reported (Hohreiter & Rigg 2001, Parker et al 2002.…”

“…A. japonicus is also listed as a CITES Appendix I species (Kaneko & Matsui 2004). The present study aimed to establish a safe and effective method for eradicating Bd in the Japanese giant salamander.Although a number of methods for eradicating Bd have been reported to date (Parker et al 2002, Woodhams et al 2003, Forzán et al 2008, Bishop et al 2009, Garner et al 2009, Nichols & Lamirande 2009, Berger et al 2010, Martel et al 2011, most of these reports have focused on anuran taxa. However, several groups have recently reported methods for treating chytridiomycosis in urodeles.…”

“…The effective and safe eradication of Bd is necessary in order to prevent mortality in captive colonies, reduce the risk of the disease spreading, and better manage the disease in threatened wild populations (Berger et al 2010). The present study was therefore conducted with the objective of establishing a simple, effective and safe Bd eradication program for the Japanese giant salamander, which is a rare and protected species in Japan.A number of Bd eradication initiatives have been proposed (Parker et al 2002, Woodhams et al 2003, Forzán et al 2008, Bishop et al 2009, Garner et al 2009, Berger et al 2010, Martel et al 2011. One method exploits the low heat resistance of Bd (Woodhams et al 2003), whereas others using formalin and malachite green have also been reported (Hohreiter & Rigg 2001, Parker et al 2002.…”

Experimental infection of self-cured Leiopelma archeyi with the amphibian chytrid Batrachochytrium dendrobatidis

“…However, when retested at the research facility, all except one frog had self cured. The last frog also became negative after a short course of topical chloramphenicol (Bishop et al 2009). In addition to this unexpected self cure in captive frogs held at conditions ideal for Bd, the prevalence of Bd in the Whareorino population increased over the next 3 yr, but the abundance of frogs did not appear to decline (Shaw et al 2008a).…”