Snake fungal disease: update and first described cases in Ontario
Nicole Nemeth, Lenny Shirose, Doug Campbell, Hugh Cai, Claire Jardine
Snake fungal disease (SFD) is a recently described condition of wild snakes in North America, and is caused by infection with Ophidiomyces ophiodiicola. The disease was first documented in wild snakes in New Hampshire in 2006, and has since been reported in 16 U.S. states in a variety of snake species. Grossly, scabs and crusts are on scales or skin, sometimes with underlying pustules or ulcers, subcutaneous nodules (often facial), ocular cloudiness, and dysecdysis. Histopathology includes hyperkeratosis, granulomatous dermatitis, and ulceration. Lesions may extend to underlying muscle and bone. Ontario represents the northern extent of the geographic ranges of numerous endangered snake species that are likely susceptible to SFD. Therefore, a better understanding of the prevalence and potential effects of SFD in Ontario is needed.
The first documentation of SFD in Canada occurred in a free-ranging eastern foxsnake (Pantherophis vulpinus) from southwestern Ontario in 2015; 3 additional foxsnakes have since been diagnosed. Diagnostic evaluation revealed characteristic lesions that tested PCR-positive for O. ophiodiicola. Based on these findings, additional studies to assess the prevalence and distribution of this fungus in Ontario have been initiated. These include testing of opportunistically collected skin swabs from live snakes, carcasses, and the environment, along with continued diagnostic evaluations.
We thank the following for sample submissions and logistical support: Tony Braithwaite (Kingsville Animal Clinic), Steve Marks (AMEC-Windsor, ON), Tarra Degazio and Tammy Dobbie (Point Pelee National Park), Emily Slavik and Pilar Manorome (Rondeau Provincial Park), Jacqueline Litzgus (Laurentian University), Christina Davy (Ontario Ministry of Natural Resources and Forestry), consultants at Blazing Star Environmental and Natural
Figure 1. Gross lesions of SFD may include scabs and crusts on scales or skin (Figs. 1A-E), underlying pustules or ulcers, subcutaneous nodules on the head, neck, and body, ocular opacity (Fig. 1F), and dysecdysis. The above are examples of more chronic lesions in an eastern foxsnake over a 3-year period (2011-1A; 2014-1B,C), queensnake (1D, F) and eastern foxsnake (1E).
Figure 2. Fungi (arrows) within a focus of necrosis within a hyperplastic and disorganized epidermis with scattered heterophils: H&E (2A), GMS (2B), PAS (2C).
Figure 3. Locations of O. ophiodiicola PCR- and SFD-positive snakes in Ontario in 2012-16.
This article is based on a poster presented at the annual meeting of the American College of Veterinary Pathologists, 2016.