27th Annual Meeting and Symposium of the
Desert Tortoise Council, March 22-24, 2002
Abstracts

STUDENT PAPER

Prevalence of URTD in Captive Desert Tortoises on and Adjacent to Fort Irwin: Potential Impacts to Wild Populations

April Johnson¹, Elliott Jacobson², David J Morafka³, Francesco Origgi², and Lori Wendland^2
1University of Illinois College of Veterinary Medicine, Urbana, IL 61802;
²University of Florida, Gainesville, FL 32610; 
³California State University Dominguez Hills, Carson, CA 90747

Captive desert tortoises on the grounds of Ft. Irwin and representative tortoises kept by private individuals in surrounding towns, were sampled over the summers of 2000 and 2001 for exposure to a tortoise Herpesvirus and Mycoplasma agassizii, two pathogens known or suspected to cause signs of URTD in desert and other species of tortoises. In 2000, 162 tortoises were tested by Enzyme Linked Immunosorbent Assay (ELISA) for exposure to Mycoplasma agassizii, and 111 of these same tortoises were also tested by ELISA for exposure to Herpesvirus. Results demonstrated 80% were positive, 6.4% suspect, and 13.6% negative for exposure to M. agassizii. 26% were positive for exposure to Herpesvirus, and the remaining 74% were negative. Of the 29 tortoises testing positive for Herpesvirus, 24 were positive for exposure to both M. agassizii and Herpesvirus.

In 2001, 47 tortoises were sampled for exposure to M. agassizii. Of these, 21 samples were from tortoises not previously sampled, of which 18 were positive on ELISA, and 3 were negative. The remaining 26 samples were collected from tortoises that tested positive in 2000 and had clinical signs of disease (nasal discharge, conjunctivitis, palpebral edema), and who according to owners were still showing signs. All 26 were still positive on ELISA with an average rise in ratio of 9.00.

Due to the high prevalence of captive tortoises exposed to M. agassizii and Herpesvirus, tortoises may pose a serious threat of pathogen introduction to surrounding naïve wild populations. One of the 162 tortoises tested in 2000 is potentially back in the wild having dug itself out of the owner's yard. Education of tortoise owners is an essential aspect to helping decrease the risk of captive tortoises spreading disease to wild tortoise populations on Ft. Irwin.