DAO 105:89-99 (2013)  -  doi:10.3354/dao02625

Co-infection by alveolate parasites and frog virus 3-like ranavirus during an amphibian larval mortality event in Florida, USA

Jan H. Landsberg1,*, Yasunari Kiryu1, Maki Tabuchi1, Thomas B. Waltzek2, Kevin M. Enge3, Sarah Reintjes-Tolen4, Asa Preston5, Allan P. Pessier

1Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission, St. Petersburg, Florida 33701, USA
2Department of Environmental and Global Health, College of Public Health Professions, and 4Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida 32611, USA
3Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission, Gainesville, Florida 32601, USA
5Amphibian Disease Laboratory, Wildlife Disease Laboratories, Institute for Conservation Research, San Diego Zoo Global, San Diego, California 92112, USA

ABSTRACT: A multispecies amphibian larval mortality event, primarily affecting American bullfrogs Lithobates catesbeianus, was investigated during April 2011 at the Mike Roess Gold Head Branch State Park, Clay County, Florida, USA. Freshly dead and moribund tadpoles had hemorrhagic lesions around the vent and on the ventral body surface, with some exhibiting a swollen abdomen. Bullfrogs (100%), southern leopard frogs L. sphenocephalus (33.3%), and gopher frogs L. capito (100%) were infected by alveolate parasites. The intensity of infection in bullfrog livers was high. Tadpoles were evaluated for frog virus 3 (FV3) by histology and PCR. For those southern leopard frog tadpoles (n = 2) whose livers had not been obscured by alveolate spore infection, neither a pathologic response nor intracytoplasmic inclusions typically associated with clinical infections of FV3-like ranavirus were noted. Sequencing of a portion (496 bp) of the viral major capsid protein gene confirmed FV3-like virus in bullfrogs (n = 1, plus n = 6 pooled) and southern leopard frogs (n = 1, plus n = 4 pooled). In July 2011, young-of-the-year bullfrog tadpoles (n = 7) were negative for alveolate parasites, but 1 gopher frog tadpole was positive. To our knowledge, this is the first confirmed mortality event for amphibians in Florida associated with FV3-like virus, but the extent to which the virus played a primary role is uncertain. Larval mortality was most likely caused by a combination of alveolate parasite infections, FV3-like ranavirus, and undetermined etiological factors.


KEY WORDS: Alveolate parasite · Ranavirus · Frog virus 3 · Amphibian mortality · Bullfrog · Southern leopard frog · Gopher frog · Tadpole


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Cite this article as: Landsberg JH, Kiryu Y, Tabuchi M, Waltzek TB and others (2013) Co-infection by alveolate parasites and frog virus 3-like ranavirus during an amphibian larval mortality event in Florida, USA. Dis Aquat Org 105:89-99

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