Molecular Characterization of a Coccidian Parasite of the Adrenal Gland in Leatherback Turtles (Dermochelys coriacea)
American Association of Zoo Veterinarians Conference 2007
James F.X. Wellehan, Jr.1, DVM, MS, DACZM, DACVM; Brian A. Stacy1, DVM, DACVP; Salvatore Frasca Jr.2, VMD, PhD, DACVP; Charles J. Innis3, VMD; E. Scott Weber3, MS, VMD; Constance Merigo3; C. Rogers Williams4, VMD; Bridget Dunnigan4, DVM; Allen M. Foley5, PhD
1College of Veterinary Medicine, University of Florida, Gainesville, FL, USA; 2Department of Pathobiology and Veterinary Science, University of Connecticut, Storrs, CT, USA; 3New England Aquarium, Central Wharf, Boston, MA, USA; 4Woods Hole Science Aquarium, Woods Hole, MA, USA; 5Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, Jacksonville, FL, USA
Leatherback turtle (Dermochelys coriacea) populations have undergone dramatic declines, decreasing over 70% globally in less than one generation.1 Very little is known about disease in this species, and the scant reports available deal primarily with opportunistic secondary bacterial infections. At necropsy of a wild leatherback turtle, a protozoan parasite that largely effaced normal adrenal tissue was identified histologically. The animal was assessed to be in good general health as indicated by nutritional status and evidence of recent feeding. Degenerate PCR primers targeting the apicomplexan small subunit ribosomal RNA gene were used to amplify products from adrenal tissue. Nucleotide sequencing of the PCR product revealed it to represent a novel coccidian parasite. Comparative sequence analysis shows that this organism is a member of the family Eimeriidae that diverges early in the Eimerian evolutionary history. The adrenal tropism of this coccidian is unique and this parasite likely represents a novel species. Similar findings were identified in two other leatherbacks and molecular confirmation that this is the same organism, as well as comparative histopathologic and ultrastructural studies, are currently ongoing. The consensus PCR protocol used here can be used to obtain sequence data for characterization of novel apicomplexan parasites. Further understanding and characterization of this parasite is needed to determine its role in leatherback health and significance to populations.
1. Spotila, J., A. Dunham, A. Leslie, A. Steyermark, P. Plotkin, and F. Paladino. 1996. Worldwide population decline of Dermochelys coriacea: are leatherback turtles going extinct? Chelonian Conserv. Biol. 2(2):209–222.