AUTHOR=Ghose Sonia L. , Yap Tiffany A. , Byrne Allison Q. , Sulaeman Hasan , Rosenblum Erica Bree , Chan-Alvarado Alan , Chaukulkar Shruti , Greenbaum Eli , Koo Michelle S. , Kouete Marcel T. , Lutz Kurt , McAloose Denise , Moyer Alessandra J. , Parra Eliseo , Portik Daniel M. , Rockney Heidi , Zink Andrew G. , Blackburn David C. , Vredenburg Vance T. TITLE=Continent-wide recent emergence of a global pathogen in African amphibians JOURNAL=Frontiers in Conservation Science VOLUME=4 YEAR=2023 URL=https://www.frontiersin.org/journals/conservation-science/articles/10.3389/fcosc.2023.1069490 DOI=10.3389/fcosc.2023.1069490 ISSN=2673-611X ABSTRACT=Introduction

Emerging infectious diseases are increasingly recognized as a global threat to wildlife. Pandemics in amphibians, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), have resulted in biodiversity loss at a global scale. Genomic data suggest a complex evolutionary history of Bd lineages that vary in pathogenicity. Africa harbors a significant proportion of global amphibian biodiversity, and multiple Bd lineages are known to occur there; yet, despite the decline of many host species, there are currently no described Bd-epizootics. Here, we describe the historical and recent biogeographical spread of Bd and assess its risk to amphibians across the continent of Africa.

Methods

We provide a 165-year view of host-pathogen interactions by (i) employing a Bd assay to test 4,623 specimens (collected 1908–2013); (ii) compiling 12,297 published Bd records (collected 1852–2017); (iii) comparing the frequency of Bd-infected amphibians through time by both country and region; (iv) genotyping Bd lineages; (v) histologically identifying evidence of chytridiomycosis, and (vi) using a habitat suitability model to assess future Bd risk.

Results

We found a pattern of Bd emergence beginning largely at the turn of the century. From 1852–1999, we found low Bd prevalence (3.2% overall) and limited geographic spread, but after 2000 we documented a sharp increase in prevalence (18.7% overall), wider geographic spread, and multiple Bd lineages that may be responsible for emergence in different regions. We found that Bd risk to amphibians was highest in much of eastern, central, and western Africa.

Discussion

Our study documents a largely overlooked yet significant increase in a fungal pathogen that could pose a threat to amphibians across an entire continent. We emphasize the need to bridge historical and contemporary datasets to better describe and predict host-pathogen dynamics over larger temporal scales.