Researchers have developed a ground-breaking new diagnostic device for the rapid detection of the fungal pathogen Batrachochytrium dendrobatidis (Bd).
New ‘frog-swab’ testing device revolutionises diagnosis of the deadly amphibian chytridiomycosis disease
University of Exeter researchers, Dr. Michael Dillon, Dr. Jamie Stevens, and Dr. Chris Thornton have joined forces with Dr. Andrew Bowkett of the Whitley Wildlife Conservation Trust in developing a ground-breaking new diagnostic device for the rapid detection of the fungal pathogen Batrachochytrium dendrobatidis (Bd). This pathogen causes chytridiomycosis, a lethal skin disease affecting amphibians and contributing to their dramatic and worrying decline in populations worldwide.
Similar to a commercial pregnancy-style test, the portable antigen-based lateral flow device (LFD) can detect the presence of Bd in a skin swab from an infected frog, salamander or snake-like caecilian in just 15 minutes. It also detects the related salamander pathogen Batrachochytrium salamandrivorans. This represents a significant improvement on current detection protocols which can take weeks and need specialist laboratories. Although the prototype was 100% accurate when tested on naturally infected tissue samples, further testing is required under a wider range of field conditions. A research article describing the new device has been published by the journal Microbial Biotechnology.
Likely aided in its spread by the global trade in amphibian species, Bd has now been detected in every continent where amphibians occur and is responsible for the greatest disease-driven loss of biodiversity ever documented. This has led the World Organization for Animal Health to recommend that all imported and exported amphibians now be screened for its presence. Visible symptoms of Bd infection such as sluggishness in movement, weight loss and a thickening of the skin are frequently ambiguous and cases were previously difficult to diagnose without the use of expensive and invasive procedures. The simple, single-step diagnostic test is the first of its kind to be developed for tracking this type of pathogen in amphibians and will likely revolutionise its detection in the field.
“A similar device used to detect the fungal disease invasive pulmonary aspergillosis in immuno-compromised hospital patients has revolutionised diagnosis of a deadly human pathogen and we anticipate a similar impact of this LFD, in allowing real-time tracking of the spread of this deadly disease in amphibians”, said Dr Thornton, in whose laboratory the test was developed.
Dr Bowkett said of the device: “It’s a quick and easy test that will reduce diagnosis time of chytridiomycosis from days to minutes. This could transform amphibian quarantine and translocation practices and vastly reduce the fungus’ spread.”
Josephine Paris is the Graduate Research Assistant on the project, responsible for promoting the new device to zoos and the wider amphibian conservation community. She said: “The next stage of the project is to start testing the LFDs for research purposes. We have confirmation that frogs testing positive for chytridiomycosis will be swabbed in Monserrat, and we have also distributed the device to Heathrow Airport Animal Reception Centre.”
Dillon, M.J., Bowkett, A.E., Bungard, M.J., Beckman, K.M., O'Brien, M.F., Bates, K., Fisher, M.C., Stevens, J.R. and Thornton, C.R. (2016). Tracking the amphibian pathogens Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans using a highly specific monoclonal antibody and lateral‐flow technology. Microbial Biotechnology.
Date: 24 February 2017