Investigation of Amphibian Mortality Events in Wildlife Reveals an On-Going Ranavirus Epidemic in the North of the Netherlands.
In the four years following the first detection of ranavirus (genus Ranavirus, family Iridoviridae) infection in Dutch wildlife in 2010, amphibian mortality events were investigated nationwide to detect, characterize and map ranaviruses in amphibians over time, and to establish the affected host species and the clinico-pathological presentation of the disease in these hosts. The ultimate goal was to obtain more insight into ranavirus disease emergence and ecological risk. In total 155 dead amphibians from 52 sites were submitted between 2011 and 2014, and examined using histopathology, immunohistochemistry, virus isolation and molecular genetic characterization. Ranavirus-associated amphibian mortality events occurred at 18 sites (35%), initially only in proximity of the 2010 index site. Specimens belonging to approximately half of the native amphibian species were infected, including the threatened Pelobates fuscus (spadefoot toad). Clustered massive outbreaks involving dead adult specimens and ranavirus genomic identity indicated that one common midwife toad virus (CMTV)-like ranavirus strain is emerging in provinces in the north of the Netherlands. Modelling based on the spatiotemporal pattern of spread showed a high probability that this emerging virus will continue to be detected at new sites (the discrete reproductive power of this outbreak is 0.35). Phylogenetically distinct CMTV-like ranaviruses were found in the south of the Netherlands more recently. In addition to showing that CMTV-like ranaviruses threaten wild amphibian populations not only in Spain but also in the Netherlands, the current spread and risk of establishment reiterate that understanding the underlying causes of CMTV-like ranavirus emergence requires international attention.
Dutch Wildlife Health Centre, Utrecht University, Utrecht, The Netherlands.
Jolianne M
JM
Rijks
Dutch Wildlife Health Centre, Utrecht University, Utrecht, The Netherlands.|Department of Pathobiology, Utrecht University, Utrecht, The Netherlands.
Bernardo
B
Saucedo
Reptile, Amphibian and Fish Conservation Netherlands, Nijmegen, The Netherlands.
Annemarieke
A
Spitzen-van der Sluijs
MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom.
Gavin S
GS
Wilkie
Dutch Wildlife Health Centre, Utrecht University, Utrecht, The Netherlands.|Department of Pathobiology, Utrecht University, Utrecht, The Netherlands.
Alphons J A M
AJ
van Asten
Department of Farm Animal Health, Utrecht University, Utrecht, The Netherlands.
Jan
J
van den Broek
Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Merelbeke, Belgium.
Roschong
R
Boonyarittichaikij
Department of Pathobiology, Utrecht University, Utrecht, The Netherlands.
Marisca
M
Stege
Reptile, Amphibian and Fish Conservation Netherlands, Nijmegen, The Netherlands.
Fleur
F
van der Sterren
Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Merelbeke, Belgium.
An
A
Martel
Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Merelbeke, Belgium.
Frank
F
Pasmans
MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom.
Joseph
J
Hughes
Dutch Wildlife Health Centre, Utrecht University, Utrecht, The Netherlands.|Department of Pathobiology, Utrecht University, Utrecht, The Netherlands.
Andrea
A
Gröne
Department of Pathobiology, Utrecht University, Utrecht, The Netherlands.
Steven J
SJ
van Beurden
Dutch Wildlife Health Centre, Utrecht University, Utrecht, The Netherlands.|Department of Pathobiology, Utrecht University, Utrecht, The Netherlands.
Marja J L
MJ
Kik
D000663:Amphibians / Q000821:virology*; D000818:Animals; D000835:Animals, Wild; D004266:DNA Virus Infections / Q000453:epidemiology / Q000235:genetics*; D058872:Epidemics; D009336:Necrosis / Q000821:virology; D009426:Netherlands; D010802:Phylogeny; D017995:Ranavirus / Q000472:pathogenicity*; D016415:Sequence Alignment