Glove decontamination procedures to prevent pathogen and DNA cross-contamination among frogs.

Working with aquatic organisms often requires handling multiple individuals in a single session, potentially resulting in cross-contamination by live pathogens or DNA. Most researchers address this problem by disposing of gloves between animals. However, this generates excessive waste and may be impractical for processing very slippery animals that might be easier to handle with cotton gloves. We tested methods to decontaminate cotton or nitrile gloves after contamination with cultured Batrachochytrium dendrobatidis (Bd) or after handling heavily Bd-infected Xenopus laevis with layered cotton and nitrile gloves. Bleach eliminated detectable Bd DNA from culture-contaminated nitrile gloves, but gloves retained detectable Bd DNA following ethanol disinfection. After handling a Bd-infected frog, Bd DNA contamination was greatly reduced by removal of the outer cotton glove, after which either bleach decontamination or ethanol decontamination followed by drying hands with a paper towel lowered Bd DNA below the detection threshold of our assay. These results provide new options to prevent pathogen or DNA cross-contamination, especially when handling slippery aquatic organisms. However, tradeoffs should be considered when selecting an animal handling procedure, such as the potential for cotton gloves to abrade amphibian skin or disrupt skin mucus. Disposing of gloves between animals should remain the gold standard for maintaining biosecurity in sensitive situations.

Dynamic effects of thermal acclimation on chytridiomycosis infection intensity and transmission potential in Xenopus laevis.

The pandemic amphibian pathogen Batrachochytrium dendrobatidis (Bd) can cause more severe infections with variable temperatures owing to delays in host thermal acclimation following temperature shifts. However, little is known about the timing of these acclimation effects or their consequences for Bd transmission. We measured how thermal acclimation affects Bd infection in Xenopus laevis, using a timing-of-exposure treatment to investigate acclimation effect persistence following a temperature shift. Consistent with a delay in host acclimation, warm-acclimated frogs exposed to Bd immediately following a temperature decrease (day 0) developed higher infection intensities than frogs already acclimated to the cool temperature. This acclimation effect was surprisingly persistent (five weeks). Acclimation did not affect infection intensity when Bd exposure occurred one week after the temperature shift, indicating that frogs fully acclimated to new temperatures within 7 days. This suggests that acclimation effect persistence beyond one week post-exposure was caused by carry-over from initially high infection loads, rather than an extended delay in host acclimation. In a second experiment, we replicated the persistent thermal acclimation effects on Bd infection but found no acclimation effects on zoospore production. This suggests that variable temperatures consistently exacerbate individual Bd infection but may not necessarily increase Bd transmission.