The Changing Epidemiology of Ophidiomyces in Free-Ranging Snakes: Surveillance, Experimental Challenge, and Development of New Diagnostics
American Association of Zoo Veterinarians Conference 2014
Matt Allender1, DVM, MS, PhD, DACZM; Dan Wylie2, BS; Sarah Wylie2, BS; Michael Dreslik2, MS, PhD; Christopher Phillips2, MS, PhD; David Bunick1, PhD; Carol Maddox3, MS, PhD
1Department of Comparative Biosciences and 3Department of Pathobiology, College of Veterinary Medicine, University of Illinois, Urbana, IL, USA; 2Prairie Research Institute, Illinois Natural History Survey, University of Illinois, Champaign, IL, USA
With the current rate of declines in global biodiversity, it is apparent that wildlife diseases are serving as additional threats to population declines and potentially species extinctions. The emerging fungal pathogen, Ophidiomyces ophiodiicola, (snake fungal disease; SFD) has been recently reported in free-ranging pit viper populations from at least ten states. Health assessments prior to and after the emergence of this pathogen in a population of massasaugas demonstrate the utility of active clinical surveillance for identifying this pathogen. The disease presents as facial disfiguration due to granulomatous dermatitis, myositis, and osteomyelitis with intralesional fungi. Since 2012, more than a dozen new species of venomous and non-venomous species have been confirmed with SFD across more than 15 states. An experimental challenge was performed in the cottonmouth (Agkistrodon piscivorus) to describe the progression of disease, identify antemortem testing strategies, and develop a model for future studies. Concurrently, a real-time PCR was developed that is 1000 times more sensitive than conventional PCR and allowed detection of subclinical infections in these animals. Furthermore, this assay allowed detection of Ophidiomyces in swab samples, thus providing another means to monitor populations. The prevalence of SFD is variable over time and trends in hematological and biochemical data are fairly consistent with results obtained prior to the emergence. However, future efforts should continue to evaluate all possible mechanisms to identify this disease to assess the health of the population in the face of new unknown threats.