Apparent absence of Batrachochytrium salamandrivorans in wild urodeles in the United Kingdom

Andrew A Cunningham,Trevelyan J Mckinley,Liam D Fitzpatrick,Owen N Wright,Freya Smith,Matthew W Perkins,Becki Lawson

doi:10.1038/s41598-019-39338-4

Andrew A Cunningham, Trevelyan J Mckinley + Show 5 more

Open Access

https://doi.org/10.1038/s41598-019-39338-4

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Abstract

Whether an infectious disease threat to wildlife arises from pathogen introduction or the increased incidence of an already-present agent informs mitigation policy and actions. The prior absence of a pathogen can be difficult to establish, particularly in free-living wildlife. Subsequent to the epidemic emergence of the fungus, Batrachochytrium salamandrivorans (Bsal), in mainland Europe in 2010 and prior to its detection in captive amphibians in the United Kingdom (UK), we tested archived skin swabs using a Bsal-specific qPCR. These samples had been collected in 2011 from 2409 wild newts from ponds across the UK. All swabs were negative for Bsal. Bayesian hierarchical modelling suggests that Bsal was absent from, or present at very low levels in, these ponds at the time of sampling. Additionally, surveillance of newt mortality incidents, 2013–2017, failed to detect Bsal. As this pathogen has been shown to be widespread in British captive amphibian collections, there is an urgent need to raise awareness of the importance of effective biosecurity measures, especially amongst people with captive amphibians, to help minimise the risk of Bsal spreading to the wild. Continued and heightened wild amphibian disease surveillance is a priority to provide an early warning system for potential incursion events.

Highlights

The chytrid fungus, Batrachochytrium salamandrivorans (Bsal) is a recently-discovered, emerging pathogen causing epidemic mortality and population declines of urodele amphibians in The Netherlands, Belgium and Germany[1,2]
The alpine newt (Ichthyosaura alpestris), which is susceptible to fatal chytridiomycosis following experimental challenge with Bsal, and which has been found to be infected in the wild in mainland Europe[2,5], is an invasive species in the United Kingdom (UK) with naturalised populations widely distributed across England and in parts of Scotland and Wales[12]
We capitalise on existing sample archives and on disease surveillance to evaluate the likelihood of Bsal presence in wild newts in the UK, with the aim of informing mitigation strategies and contingency planning to prevent the incursion and impact of this pathogen on UK wildlife

Summary

Introduction

The chytrid fungus, Batrachochytrium salamandrivorans (Bsal) is a recently-discovered, emerging pathogen causing epidemic mortality and population declines of urodele amphibians (newts and salamanders) in The Netherlands, Belgium and Germany[1,2]. Whereas no evidence of Bsal infection has been found on screening captive pet salamanders in the United States of America[6], or on limited testing in Canada[7], the pathogen has been detected in urodeles sampled from zoological and hobbyist collections in Europe, including in the United Kingdom (UK)[8,9,10]. This newly-discovered pathogen can infect anurans, it is only known to cause disease in urodeles, albeit with huge variance in infection outcome amongst species, ranging from tolerance to death[2,11]. We capitalise on existing sample archives and on disease surveillance to evaluate the likelihood of Bsal presence in wild newts in the UK, with the aim of informing mitigation strategies and contingency planning to prevent the incursion and impact of this pathogen on UK wildlife

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