title: Microscopic aquatic predators strongly affect infection dynamics of a globally emerged pathogen.
abstract: Research on emerging infectious wildlife diseases has placed particular emphasis on host-derived barriers to infection and disease. This focus neglects important extrinsic determinants of the host/pathogen dynamic, where all barriers to infection should be considered when ascertaining the determinants of infectivity and pathogenicity of wildlife pathogens. Those pathogens with free-living stages, such as fungi causing catastrophic wildlife declines on a global scale, must confront lengthy exposure to environmental barriers before contact with an uninfected host. Hostile environmental conditions therefore have the ability to decrease the density of infectious particles, reducing the force of infection and ameliorating the impact as well as the probability of establishing an infection. Here we show that, in nature, the risk of infection and infectious burden of amphibians infected by the chytrid fungus Batrachochytrium dendrobatidis (Bd) have a significant, site-specific component, and that these correlate with the microfauna present at a site. Experimental infections show that aquatic microfauna can rapidly lower the abundance and density of infectious stages by consuming Bd zoospores, resulting in a significantly reduced probability of infection in anuran tadpoles. Our findings offer new perspectives for explaining the divergent impacts of Bd infection in amphibian assemblages and contribute to our understanding of ecosystem resilience to colonization by novel pathogens.
authors.affiliation: Department of Conservation Biology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany; Université de Toulouse; UPS, INPT; EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement); 118 Route de Narbonne, 31062 Toulouse, France; CNRS, EcoLab, 31062 Toulouse, France. Electronic address: ds@die-schmellers.de.
authors.forename: Dirk S
authors.initials: DS
authors.lastname: Schmeller
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Mark
authors.initials: M
authors.lastname: Blooi
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: An
authors.initials: A
authors.lastname: Martel
authors.affiliation: Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK.
authors.forename: Trenton W J
authors.initials: TWJ
authors.lastname: Garner
authors.affiliation: Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Fisher
authors.affiliation: Université de Toulouse; UPS, INPT; EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement); 118 Route de Narbonne, 31062 Toulouse, France; CNRS, EcoLab, 31062 Toulouse, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Azemar
authors.affiliation: Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK; Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK.
authors.forename: Frances C
authors.initials: FC
authors.lastname: Clare
authors.affiliation: CNRS, EcoLab, 31062 Toulouse, France.
authors.forename: Camille
authors.initials: C
authors.lastname: Leclerc
authors.affiliation: CNRS, EcoLab, 31062 Toulouse, France.
authors.forename: Lea
authors.initials: L
authors.lastname: Jäger
authors.affiliation: CNRS, EcoLab, 31062 Toulouse, France.
authors.forename: Michelle
authors.initials: M
authors.lastname: Guevara-Nieto
authors.affiliation: Department of Conservation Biology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany; Université de Toulouse; UPS, INPT; EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement); 118 Route de Narbonne, 31062 Toulouse, France; CNRS, EcoLab, 31062 Toulouse, France.
authors.forename: Adeline
authors.initials: A
authors.lastname: Loyau
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Frank
authors.initials: F
authors.lastname: Pasmans
mesh_terms: D000818:Animals; D001001:Anura / Q000382:microbiology; D008411:Chytridiomycota / Q000302:isolation & purification*; D009181:Mycoses; D014867:Water; D014871:Water Microbiology
chemical_list: D014867:Water