Determining the Significance of a Treponema-Like Organism Isolated from Australia’s Most Critically Endangered Mammal, the Gilbert’s Potoroo (Potorous gilbertii)
American Association of Zoo Veterinarians Conference 2007

Rebecca Vaughan1,2, BSc, BVMS; Nicky Buller3, BSc, PhD; Tony Friend4, BSc, PhD; Cree Monaghan1, BSc, BVMS, MSc; Stan Fenwick2, BVMS, MSc, PhD; Kristin Warren2, BSc, BVMS, PhD

1Veterinary Department, Perth Zoo, South Perth, WA, Australia; 2School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, WA, Australia; 3Western Australian Department of Agriculture and Food, South Perth, WA, Australia; 4Department of Environment and Conservation Science Division, Albany Research, Albany, WA, Australia


The Gilbert’s potoroo (Potorous gilbertii) is Australia’s most critically endangered mammal with an estimated population of less than 30 individuals.2 There has been a long history of balanoposthitis (inflammation of the penis and prepuce) in individuals from both wild and captive populations of this species.1 Clinically, this is evident as crusty green tenacious preputial exudates with associated ulceration. Bacteriologic examination has revealed a number of potential pathogens amongst the mixed bacteria isolated. The most significant is a Treponema-like organism. Sequencing results from these spirochetes identified a 164-nucleotide segment of 16S ribosomal RNA, which had 92% similarity to Treponema species. Prevalence of infection with the Treponema-like organism was 17/26 (65.38%).

Tissue biopsy for culture, silver staining, and histopathology revealed a chronic inflammatory response with secondary epithelial hyperplasia in conjunction with moderate numbers of spirochetes strongly suggesting a causative relationship. Numerous coccobacilli were also found. These were from the Actinobacillus/Pasteurella group identified by partial 16S rRNA sequencing. Epidemiologic studies involved relating the nature and severity of the discharge and the subsequent identification of spirochetes (via dark field microscopy and via urogenital swabbing for PCR) to sex affected, time of year, age of animal and geographic location. These studies revealed a higher prevalence in males; however, there was no difference in prevalence between seasons or by geographic location.

This infection appears to play a highly significant role in the recovery program of the critically endangered Gilbert’s potoroo given the severity of balanoposthitis and reproductive dysfunction that is especially evident in the reproductively quiescent captive population.

Literature Cited

1.  Courtenay, J., T. Start, and A.A. Burbidge. 2005. Gilbert’s potoroo recovery plan 1998–2007 (Updated 2005). Department of Conservation Western Australia.

2.  International Union for the Conservation of Nature and Natural Resources (IUCN). 1994. IUCN Red List Categories. IUCN Species Survival Commission, Gland, Switzerland.


Speaker Information
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Rebecca Vaughan, BSc, BVMS
Veterinary Department
Perth Zoo
South Perth, WA, Australia

School of Veterinary and Biomedical Sciences
Murdoch University
Murdoch, WA, Australia

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