Texas Chronic Wasting Disease Management Plan
Revised (April 24, 2003)
Prepared by
The Texas Animal Health Commission
And
The Texas Parks and Wildlife Department
EXECUTIVE SUMMARY
Texas Animal Health Commission (TAHC) and Texas Parks and Wildlife Department (TPWD) cooperatively developed the Texas Chronic Wasting Disease Management Plan. The agencies recognize the need for full cooperation and partnership among government agencies, groups, private landowners, hunters and the public should CWD occur in Texas. CWD is a reportable disease and TAHC has authority for reporting and tracking this disease in alternative livestock, which includes elk, and white-tailed deer and mule deer held under authority of Scientific Breeder Permits. TPWD has regulatory authority for free-ranging white-tailed deer and mule deer, and deer held under authority of Scientific Breeder Permits.
The Texas Chronic Wasting Disease Management Plan describes the surveillance sampling strategy and the decision-making process should CWD be detected in the State of Texas. The plan provides information about CWD, a comprehensive management approach to reduce the threat of the disease to susceptible free-ranging and captive-species and an approach for developing effective management of CWD should it emerge within the State.
Chronic Wasting Disease (CWD) is a little known, infectious neurological disease in the family of infectious diseases known as transmissible spongiform encephalopathies (TSEs). CWD is only known to occur in white-tailed deer, mule deer, black-tailed deer and elk. It has not been identified, to date, in other species. Other TSEs include bovine spongiform encephalopathy (BSE) in cattle, scrapie in domestic sheep, Creutzfeldt-Jakob disease (CJD) and a new variant (vCJD) in humans. CWD is a progressive, fatal disease of susceptible cervids with no known immunity, vaccine, or treatment. CWD HAS NOT BEEN FOUND IN TEXAS. CWD has been found in free-ranging and/or captive cervids in 13 states or Canadian provinces. CWD has not been found to be contagious to other cervids, livestock or humans at this time. Although BSE has been associated with a new vCJD in humans, the Center for Disease Control reports there are no parallel cases associated with CWD in humans in the U.S. after intensively reviewing over 575 cases of CJD. CJD occurs naturally in the population at about one in every million persons. Scrapie, a TSE in domestic sheep, has been known for over 250 years, and has not been transmitted to humans although precautions are recommended to avoid brain, spinal tissue and lymph glands in processed meat for human consumption. The World Health Organization has recommended similar precautions for deer and elk in the U.S. and there is no evidence that consumption of venison has affected humans in the endemic area where the disease has been for over 35 years.
CWD was discovered in the 1960s, and was first identified in experimental elk that had been taken from the wild and placed into the pens in northeastern Colorado. Origin of the disease may never be determined, it is speculated to have mutated from sheep scrapie or was spontaneous, no one knows. CWD received little attention until it was discovered in Nebraska and concerns were raised when free-ranging white-tailed deer in southern Wisconsin in early 2002 were confirmed as being infected with CWD. Experiments are being conducted to determine whether or not other ruminant species, including wild ruminants, exotics, domestic cattle, sheep, and goats, to determine if they may be inflected with CWD by direct or indirect contact with CWD-infected deer and elk. At this time there has been no evidence of transmission of CWD to these other species.
Targeted surveillance of clinical deer (those displaying symptoms, i.e. emaciation, staggering, excessive salivation, and tremors) was initiated statewide in Texas in the summer of 2002. These symptoms can also be representative of many other known diseases and conditions in deer in Texas. TPWD and TAHC began collecting samples from deer in the summer 2002 and during the 2002-2003 hunting season. A total of 2020 deer were sampled and all were negative for CWD, (See Appendix A: Results of CWD Sampling pg. 13) Surveillance sampling is to be continued for the next three to five years in order to determine whether or not CWD is in Texas deer populations.
In the event that a CWD positive animal should be detected in Texas, initial efforts will focus on sampling in the immediate area surrounding the location of the index animal. The sampling area should be of adequate size and contain a sufficient number of animals to detect three additional positive cases at an infection rate of two per-cent of the herd. If additional positive cases are detected in the sample, additional sampling will be necessary to determine distribution and prevalence of the disease. The index case location would be GIS referenced and mapped with a sampling area delineated. The diameter of the sampling area, from which 150 samples would be collected for example, could be eight miles in a high-density deer area and could be sixteen miles in low-density deer area. However, this sampling approach would only occur after consultation with landowners within the sample area and only through the concurrence, cooperation and assistance of the landowners.
TAHC rules would apply only to deer held under authority of Scientific Breeder Permits or elk within a holding pen or facility. Upon detection of a CWD-positive animal in a captive or penned situation and consultation with the owner, TAHC may elect to monitor the herd with special condition (i.e. double fencing) or indemnification for eradication of the herd. Landowners surrounding the holding pen or facility would be notified and sampling with landowner permission discussed.
TPWD Law Enforcement will enforce the Importation Rules as they are now in place. Violation of the TAHC importation rules is classified as a misdemeanor; however, wildlife imported illegally into Texas would be prosecuted under the Lacy Act, which is a federal felony, and TPWD and the U.S. Fish and Wildlife Service would cooperate in such a prosecution.
Contingency plans to control any potential spread of CWD include: 1) evaluation of the system where the positive is detected, 2) determination of herd attributes or physical barriers that may limit distribution and movement of animals, and therefore disease and 3) seeking cooperation, assistance, and permission of landowners potentially affected by the sampling effort. Strategies for possible treatments will be discussed and reviewed with TPWD advisory committees and affected groups.
