Johne’s Disease Investigation in Tule Elk at Grizzly Island, California
Grizzly Island Wildlife Area is a 12,900 acre habitat within California's Suisun Marsh, the largest contiguous estuarine marsh in the United States. The wildlife area is home to a herd of tule elk (Cervus elaphus nannodes) herd, California’s indigenous elk species. Serological testing of some Grizzly Island animals suggested that the herd had been exposed to or was infected with Johne’s disease, a well known, debilitating bacterial disease of cattle caused by Mycobacterium avium subsp. psuedotuberculosis. However, clinical Johne’s disease had not been observed in the herd, so the implications of the test results were unknown.
In 2000, we were asked by California Department of Fish and Wildlife to conduct an investigation into the prevalence of Johne’s disease in the elk herd. The annual management hunt provided the opportunity to perform thorough diagnostic post-mortem exams on 37 hunter-killed elk, and so during the hunt, we collected and analyzed multiple biological samples from each collected elk. We found no clinical evidence of Johne’s disease but did isolate the Johne’s organism from one elk and a related non-pathogenic bacteria Mycobacterium avium subsp. avium from five other animals. The results of our study demonstrated that tule elk can be asymptomatic reservoirs of the Johne’s disease organism, information that helps guide elk population management decisions.
Crawford, G et. al. Mycobacterium avium subsp paratuberculosis and Mycobacterium avian subsp avium infections in a tule elk herd, Journal of Wildlife Diseases 2006: http://www.jwildlifedis.org/doi/10.7589/0090-3558-42.4.715
Jon Fischer, California Department of Fish and Wildlife
Ben Gonzales, DVM, MPVM California Department of Fish and Wildlife
Elizabeth Manning, DVM PhD Johne’s Testing Center, School of Veterinary Medicine, University of Wisconsin
Jonna Mazet. DVM, MPVM, Ph Wildlife Health Center, School of Veterinary Medicine, University of California Davis
Leslie Woods, DVM, PhD California Animal Health and Food Safety Laboratory, School of Veterinary Medicine, University of California Davis
Michael Ziccardi, DVM, MPVM, PhD Wildlife Health Center, School of Veterinary Medicine, University of California Davis.
We are grateful for financial support from the University of California, Davis Wildlife Health Center, Safari International and the Rock Mountain Elk Foundation.
GRIZZLY ISLAND INFORMATION https://www.wildlife.ca.gov/Lands/Places-to-Visit/Grizzly-Island-WA