title: Environmental determinants of recent endemism of Batrachochytrium dendrobatidis infections in amphibian assemblages in the absence of disease outbreaks.
abstract: The inconsistent distribution of large-scale infection mediated die-offs and the subsequent population declines of several animal species, urges us to understand how, when, and why species are affected by disease. It is often unclear when or under what conditions a pathogen constitutes a threat to a host. Often, variation of environmental conditions plays a role. Globally Batrachochytrium dendrobatidis (Bd) causes amphibian declines; however, host responses are inconsistent and this fungus appears equally capable of reaching a state of endemism and subsequent co-existence with native amphibian assemblages. We sought to identify environmental and temporal factors that facilitate host-pathogen coexistence in northern Europe. To do this, we used molecular diagnostics to examine archived and wild amphibians for infection and general linear mixed models to explore relationships between environmental variables and prevalence of infection in 5 well-sampled amphibian species. We first detected infection in archived animals collected in 1999, and infection was ubiquitous, but rare, throughout the study period (2008-2010). Prevalence of infection exhibited significant annual fluctuations. Despite extremely rare cases of lethal chytridiomycosis in A. obstetricans, Bd prevalence was uncorrelated with this species' population growth. Our results suggest context dependent and species-specific host susceptibility. Thus, we believe recent endemism of Bd coincides with environmentally driven Bd prevalence fluctuations that preclude the build-up of Bd infection beyond the critical threshold for large-scale mortality and host population crashes.
authors.affiliation: Reptile, Amphibian & Fish Conservation Netherlands (RAVON), P.O. Box 1413, 6501, BK Nijmegen, the Netherlands; Faculty of Veterinary Medicine, Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Salisburylaan 133, B9820 Merelbeke, Belgium. a.spitzen@ravon.nl.
authors.forename: Annemarieke
authors.initials: A
authors.lastname: Spitzen-Van Der Sluijs
authors.forename: An
authors.initials: A
authors.lastname: Martel
authors.forename: Caspar A
authors.initials: CA
authors.lastname: Hallmann
authors.forename: Wilbert
authors.initials: W
authors.lastname: Bosman
authors.forename: Trenton W J
authors.initials: TW
authors.lastname: Garner
authors.forename: Pascale
authors.initials: P
authors.lastname: Van Rooij
authors.forename: Robert
authors.initials: R
authors.lastname: Jooris
authors.forename: Freddy
authors.initials: F
authors.lastname: Haesebrouck
authors.forename: Frank
authors.initials: F
authors.lastname: Pasmans
mesh_terms: D000663:Amphibians; D000818:Animals; D008411:Chytridiomycota / Q000302:isolation & purification*; D003247:Conservation of Natural Resources; D004198:Disease Susceptibility / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D016014:Linear Models; D009181:Mycoses / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D009426:Netherlands / Q000453:epidemiology; D011157:Population Dynamics; D015995:Prevalence; D012307:Risk Factors
keywords: Alytes obstetricans; Belgium; Bélgica; Países Bajos; chytridiomycosis; predominio; prevalence; quitridiomicosis; the Netherlands