Widespread presence of the pathogenic fungus Batrachochytrium dendrobatidis in wild amphibian communities in Madagascar.

Molly C Bletz,Nirhy H C Rabibisoa,Matthew C Fisher,Devin Edmonds,Franco Andreone,Gonçalo M Rosa,Elodie A Courtois,Reid N Harris,Dirk S Schmeller,Angelica Crottini,Liliane Raharivololoniaina,Miguel Vences,Ché Weldon,Falitiana C E Rabemananjara,Christopher J Raxworthy

doi:10.1038/srep08633

Abstract

Amphibian chytridiomycosis, an emerging infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been a significant driver of amphibian declines. While globally widespread, Bd had not yet been reported from within Madagascar. We document surveys conducted across the country between 2005 and 2014, showing Bd's first record in 2010. Subsequently, Bd was detected in multiple areas, with prevalence reaching up to 100%. Detection of Bd appears to be associated with mid to high elevation sites and to have a seasonal pattern, with greater detectability during the dry season. Lineage-based PCR was performed on a subset of samples. While some did not amplify with any lineage probe, when a positive signal was observed, samples were most similar to the Global Panzootic Lineage (BdGPL). These results may suggest that Bd arrived recently, but do not exclude the existence of a previously undetected endemic Bd genotype. Representatives of all native anuran families have tested Bd-positive, and exposure trials confirm infection by Bd is possible. Bd's presence could pose significant threats to Madagascar's unique “megadiverse” amphibians.

Highlights

Amphibian chytridiomycosis, an emerging infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been a significant driver of amphibian declines
In the Neotropics, approximately 67% (110 species) of the genus Atelopus disappeared across their range[9], and when Bd arrived in Panama, 41% of the amphibian diversity was lost from the highland site of El Cope[10]
In 2010, the Chytridiomycosis Working Group (CWG) was established to facilitate chytrid-related research in Madagascar and the Chytrid Emergency Cell (CEC) was created to develop specific protocols to prevent the arrival of Bd and to rapidly respond to chytridiomycosis outbreaks in Madagascar

Summary

Introduction

An emerging infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been a significant driver of amphibian declines. While some did not amplify with any lineage probe, when a positive signal was observed, samples were most similar to the Global Panzootic Lineage (BdGPL) These results may suggest that Bd arrived recently, but do not exclude the existence of a previously undetected endemic Bd genotype. Chytridiomycosis, an emerging infectious disease caused by the pathogen Batrachochytrium dendrobatidis (Bd), is recognized as playing a significant role in the rapid declines and extinctions of amphibians around the world[2,3]. The National Monitoring Plan (NMP) which biannually surveys for Bd across the island at eight selected sites was launched[31] All these activities started under the premise that Bd was absent in Madagascar, according to the surveys published before 201413–16,32; recently Bd was reported on Malagasy frogs imported to the USA for the pet trade in 201233. We present the first evidence for the widespread presence of Bd in wild amphibian populations from Bd surveys carried out from 2005–2014 at various sites across the country, and provide preliminary information about the identity of the Bd lineage

Methods

Results

Conclusion