Chytridiomycosis in an Aquarium Collection of Frogs: Diagnosis, Treatment, and Control

Abstract

The introduction of a new group of dendrobatid frogs to an established captive amphibian collection was followed by several acute mortalities in both resident and introduced frog populations. Chytridiomycosis, caused by Batrachochytrium dendrobatidis, was diagnosed by histology in two of the dead frogs. Following the diagnosis, all amphibians were moved to a specially made quarantine room with strict handling protocols and treated with itraconazole. Frogs, being terrestrial amphibians, were treated with itraconazole (Sporanox, 10 mg/ml) at 0.01% in 0.6% saline in a 5-min bath for 11 consecutive days. Axolotls (Ambystoma mexicanum) and Kaup's caecilians (Potymotyphlus kaupii), being aquatic amphibians, were treated with itraconazole administered directly in their primary tank water to achieve a concentration of 0.01% for 30 min every 5 days for four treatments. Itraconazole was removed from the tank water after 30 min by high-rate-of-flow activated charcoal filters. The treatment and quarantine procedures were successful in eradicating the disease. The few amphibian mortalities that occurred in the 18 mo after the start of the treatment have been histologically negative for the presence of chytrid fungi. The collection is now considered free of chytridiomycosis.

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

“…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. Although a variety of antifungal agents have been shown to be effective for Bd eradication in several amphibian species (Forzán et al 2008, Garner et al 2009, Nichols & Lamirande 2009, Berger et al 2010, Martel et al 2011, Briggler reported that itraconazole is not particularly well suited to treating Bd infection as it rarely killed Bd after long-term exposure, but heat treatment was more effective on an aquatic salamander (J. Briggler pers. comm.).…”

“…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.…”

Fatal chytridiomycosis and infection loss observed in captive toads infected in the wild

“…In order to clear any potential B. dendrobatidis infection, all toads (n = 162) were treated with Itraconazole post hibernation by daily bathing in a 0.01% itraconazole solution, for 11 successive days (as in Forzan et al 2008). In order to stimulate any remaining infection, the water level in the tanks was increased for a period of 2 weeks in July (as advised by Trenton Garner, Zoological Society of London).…”