Inter-Research > DAO > v102 > n2 > p163-167  
Diseases of Aquatic Organisms

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DAO 102:163-167 (2012)  -  DOI:

Granulomatous myositis associated with a novel alveolate pathogen in an adult southern leopard frog (Lithobates sphenocephalus)

Megan E. B. Jones1,4, Aníbal G. Armién2, Betsie B. Rothermel3, Allan P. Pessier1,*

1Amphibian Disease Laboratory, Wildlife Disease Laboratories, Institute for Conservation Research, San Diego Zoo Global, PO Box 120551, San Diego, California 92112-0551, USA
2Minnesota Veterinary Diagnostic Laboratory, University of Minnesota, Minnesota 55108, USA
3Archbold Biological Station, Lake Placid, Florida 33862, USA
4Present address: Department of Pathology, College of Veterinary Medicine, University of Georgia, 501 D.W. Brooks Drive, Athens, Georgia 30602, USA
*Corresponding author. Email:

ABSTRACT: Since 1999, infections with an incompletely characterized alveolate protozoan variously reported as a Dermocystidium-like organism, a Perkinsus-like agent, and Dermomycoides sp. have been associated with mortality events in tadpoles of ranid frogs from the USA. However, disease or mortality events due to this organism have not been described in post-metamorphic animals. We describe infection with a morphologically similar protozoan presenting itself as a leg mass in a free-ranging adult southern leopard frog Lithobates sphenocephalus. Using histological examination, we found a mass within skeletal muscle; this mass was composed of macrophages with intracytoplasmic, thick-walled, 4 to 6 µm in diameter, spherical basophilic protozoal organisms that exhibited green autofluorescence with epiflorescence illumination. Using transmission electron microscopy, organism cell walls were found to have electron-dense plates that, when viewed by scanning electron microscopy, were reminiscent of the thecal plates of dinoflagellates. Additional morphologic and molecular phylogenetic research is needed to resolve the taxonomic status of this organism.

KEY WORDS: Amphibian · Protozoa · Dermomycoides sp. · Ultrastructure

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Cite this article as: Jones MEB, Armién AG, Rothermel BB, Pessier AP (2012) Granulomatous myositis associated with a novel alveolate pathogen in an adult southern leopard frog (Lithobates sphenocephalus). Dis Aquat Org 102:163-167.

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