Mortality Associated with Severe Necrotizing Intestinal Amoebiasis in Captive-Housed Cranwell’s Horned Frogs (Ceratophrys cranwelli)
IAAAM 2019
Tatiana C. Weisbrod1*+; Albert B. Jeon2; Deborah B. Pouder3; Nicole I. Stacy2; Heather S. Walden2; Salvatore Frasca Jr.2; Roy P.E. Yanong3; Robert J. Ossiboff2
1Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA; 2Department of Comparative, Diagnostic, and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA; 3Tropical Aquaculture Laboratory, Program in Fisheries and Aquatic Sciences, School of Forest Resources and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Ruskin, FL, USA


Both pathogenic and commensal amoebae have been documented in a variety of amphibian hosts. Various species in the genus Entamoeba are recognized as a cause of dysenteric disease across several taxa.1,2 Clinical entamoebiasis in amphibians, however, is uncommonly reported, and most descriptions are limited to disease in individuals or a few animals.3,4,5,6,7,8 This report details a case of amoebiasis that resulted in mortality in a population of Cranwell’s horned frogs (Ceratophrys cranwelli).

Regurgitation was observed in a captive private population of approximately 1000, 4-week-old albino C. cranwelli, which was followed one week later by a spike in mortalities (nearly 150 deaths over a 3-day span). Seventeen, live, moribund frogs were submitted for post-mortem examination that included cytologic, bacteriologic, parasitologic, and histopathologic assessment. No bacterial growth was observed on brain or kidney cultures completed on 4 individuals. On cytologic examination, intestinal contents of a subset of frogs contained a large population of opalinid heterokonts and spironucleoid-like flagellates as well as a mixed population of bacteria. Blood smears from 3 animals were consistent with chronic-active systemic inflammation. Histopathologic evaluation of 6 frogs identified severe necroulcerative colitis associated with numerous intracytoplasmic amoebic trophozoites in mucosal enterocytes, and variable involvement of the small intestine. Zinc-polyvinyl alcohol fixed and trichrome stained scrapes of colonic mucosa identified amoebic trophozoites with morphology most consistent with an Entamoeba species. Further molecular and ultrastructural characterization is pending. Treatment with daily 8-hour 25 mg/gal metronidazole baths was recommended for the remaining collection and a subsequent reduction in mortalities was reported.

* Presenting author, + Student presenter

Literature Cited

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6.  Mohammad KN, Badrul MM, Mohamad N, Zainal-Abidin AH. 2013. Protozoan parasites of four species of wild anurans from a local zoo in Malaysia. Trop Biomed. 30(4):615–620.

7.  Shilton CM, Slapeta J, Shine R, Brown GP. 2018. Invasive colonic entamoebiasis in wild cane toads, Australia. Emerg Infect Dis. 24(8):1541–1543.

8.  Valentine BA, Stoskopf ML. 1984. Amebiasis in a neotropical toad. J Am Vet Med Assoc. 185:1418–1419.


Speaker Information
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Tatiana C. Weisbrod
Department of Large Animal Clinical Sciences
College of Veterinary Medicine
University of Florida
Gainesville, FL, USA

MAIN : Session 4: Pathology : Severe Necrotizing Intestinal Amoebiasis in Frogs
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