An Epizootic of Mycotic Shell Disease Associated with Nannizziopsiaceae Fungal Infection in Juvenile Wood Turtles (Glyptemys insculpta) in a Conservation Headstarting Program
2018 Joint EAZWV/AAZV/Leibniz-IZW Conference
Ellie Milnes1,2, MA, VetMB; Christopher Dutton1*, BSc, BVSc, MSc, DACZM, DECZM; Cédric Larouche1,2, DMV, IPSAV; Pauline Delnatte1, DVM, DVSc, DACZM, DECZM; Andrew Lentini1, BSc, PhD; Daniel Woodburn3, DVM, DACVP; Nicole Nemeth2, BA, DVM, PhD, DACVP; Dale Smith2, DVM, DVSc
1Toronto Zoo, Toronto, ON, Canada; 2Ontario Veterinary College, University of Guelph, Guelph, ON, Canada; 3College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Brookfield, IL, USA
The Toronto Zoo participates in the conservation of wood turtles (Glyptemys insculpta). Eggs from non-viable wild nests are collected and incubated, and juveniles raised in a protected zoo environment for one to two years before being released back to the wild. In May 2017, 40 of the 85 turtles hatched in 2016 developed multifocal, white, flaky lesions of the shell. Full- thickness shell biopsies were collected from four turtles and histopathology revealed marked parakeratotic hyperkeratosis with numerous fungal hyphae limited to the outer keratinized layer of the scutes, and no dermal inflammation. Although fungal cultures were negative, PCRs using both generic fungal primers and those specific for Nannizziopsiaceae were positive. Sequencing of a 634-bp fragment was 80–90% homologous with Nannizziopsiaceae sequences obtained from other aquatic turtle species, suggesting that the wood turtle pathogen may be a novel species in the newly-described Emydomyces genus. Suboptimal water quality, including slow-water circulation, and high stocking densities were possible precipitating factors. By January 2018, following topical chlorhexidine and clotrimazole, nebulized terbinafine, and husbandry improvements, all lesions stopped progressing, and some had regressed. Shell scrapes from similar lesions were collected from three wild wood turtles originating from the population where eggs for headstarting were collected, and fungal isolates were identical to those obtained from the captive animals. The long-term implications for this conservation program remains unclear at this stage.