Fish and Wildlife Disease

This desert tortoise has typical clinical signs of mycoplasmosis, including bubbles and drainage from the nares. Photo credit: USGS Image Gallery

Research on new and emerging diseases in the desert tortoise is underway in the Mojave and Colorado deserts of California. The desert tortoise is on state and federal lists of threatened species in parts of the Southwest.  The new diseases of interest are upper respiratory tract diseases caused by very small bacteria without cell walls in the genus Mycoplasma. Two species of Mycoplasma have been identified: Mycoplasma agassizii and M. testudineum. Each of these bacterial species may produce slightly different clinical signs of disease. The scientists involved include Dr. Kristin Berry of USGS and collaborators at the University of Florida, Drs. Mary Brown, Lori Wendland, and Elliott Jacobson. They are studying the geographic distribution, epidemiology, and pathogenesis of mycoplasmosis in desert tortoises. Tortoises with mycoplasmosis have a range of clinical signs from mild to severe, including swollen eyelids, occluded or partially occluded nares (nostrils), bubbles and purulent drainage from the eyes and nares, wheezing, lethargy, and anorexia. Some populations have experienced high mortality rates. Scientists have learned that prevalence of disease is higher in captive populations in cities than in remote areas of the desert, and that tortoise populations at the urban-desert interface are also likely to have higher incidences of the disease.

For more information contact Kristin H. Berry, Western Ecological Research Center.