Long-term eradication of the chytrid fungus Batrachochytrium dendrobatidis from a large Xenopus laevis husbandry.

Abstract

The chytrid fungus Batrachochytrium dendrobatidis (BD) poses a serious threat to amphibian species worldwide. BD infects keratinocytes of the skin and interferes with their physiological barrier function. The African clawed frog Xenopus laevis is a species with low susceptibility to BD. Nevertheless, any infection presents a challenge to the immune system and, when combined with other stressors, carries the risk of overwhelming the body's defense. Infected animals may show greater variability in their scientific output than uninfected animals. This, in turn, means that more animals have to be used, which is not in line with the 3Rs principle. Moreover, releasing the fungus into the wastewater system should clearly be avoided to prevent infection of wild amphibians. Following confirmation of BD infection in the animals by Polymerase Chain Reaction (PCR), we decided to eradicate the fungus due to the reasons outlined above. This project involved not only the treatment of our frogs but also the timely coordinated disinfection of our entire permanently installed aquarium system. Itraconazole was applied as an immersion bath for the frogs and heat was used to disinfect the aquarium system. In this report, we outline our complex approach to a logistically demanding, labor-intensive project involving a large team of staff. We emphasize the need for straightforward planning, good communication and reporting on unexpected aspects and findings.