Chronic wasting disease, a transmissible encephalopathy, has made its debut in farmed deer herds in the eastern United States. At press time, CWD had just been confirmed in five deer from two herds in Oneida County, New York. This is the first time the disease has been identified in any state east of Illinois.
Until now, CWD had been identified only in Colorado, Illinois, Kansas, Minnesota, Montana, Nebraska, New Mexico, Oklahoma, South Dakota, Utah, Wisconsin, and Wyoming. Saskatchewan and Alberta in Canada have also reported CWD infections. The disease has been found in captive animals in some states and provinces and in the wild in others. In some areas, the disease is found in both captive and wild animals.
Chronic wasting disease, first detected in 1967, has been found in members of the deer family, which include white-tailed deer, mule deer, and elk. Researchers hypothesize that prions, infectious proteins, cause the disease, but more research is needed into the fatal neurologic illness.
Responding to the positive cases in New York, Dr. William Hueston, director of the Center for Animal Health and Food Safety at the University of Minnesota, says he won't be surprised if the disease is found in additional states.
States that have experienced CWD have taken steps to regulate the movement of farmed deer and elk, but not all states have followed suit. The Department of Agriculture's Animal and Plant Health Inspection Service provides support for CWD prevention and surveillance for farmed and wild elk and deer as well as indemnification dollars for captive herds that must be destroyed. Many states, however, still struggle to fund state surveillance programs.
"The challenge is that most of the states are stretched very thin in their animal health resources," Dr. Hueston said. "Largely, legislators and legislatures have the attitude, which I perfectly understand, that if we don't have a problem, why should we pay for additional veterinary services or animal health programs? That is all well and good, as long as you don't get a new problem emerging."
The political climate is also a factor. "We are in an era where, in general, the majority of the people would like to see a smaller government and less laws, and that creates a window of opportunity for emerging diseases," Dr. Hueston said.
In New York, the responsibility for controlling CWD is shared by the USDA and two state departments. The Department of Environmental Conservation issues licenses to individuals who possess, import, or sell white-tailed deer, and also routinely tests New York's wild deer. The Department of Agriculture and Markets monitors the health and movement of all captive deer and elk for the presence of CWD. In July 2004, this department initiated the CWD Enhanced Surveillance and Monitoring Program. This program requires captive deer and elk herd owners to take various actions, including routine sampling and testing, animal identification, and an annual herd inventory.
On March 31, 2005, the NYSDAM announced they had confirmed the first case of CWD in the state. The animal, a six-year-old, white-tailed doe, was slaughtered from a captive herd as part of the state's mandatory surveillance. Preliminary tests performed at the New York State Veterinary Diagnostic Laboratory at Cornell University determined the presumptive positive, which was confirmed by the National Veterinary Services Laboratories in Ames, Iowa.
Nathan Rudgers, New York State commissioner of agriculture, said the identification demonstrated that the state control program is working. "Our control program achieves what it's intended to do, and that's to rapidly detect disease, if it's out there, and provide the proper protocols to quickly respond," he said.
The subsequent investigation revealed that one of the herds associated with the index animal had recently sent another sample to New York's veterinary diagnostic laboratory to be tested for CWD. The white-tailed deer had died from aspiration pneumonia, which is often associated with the disease. Because of the direct connection with the index herd, the department expedited the testing procedure by rerouting the sample to the NVSL, which announced the sample was positive.
The NYSDAM quarantined and depopulated the two herds in which the positive deer were found, and testing revealed three more deer with CWD from the index herd. Herds associated with the infected herds were also quarantined and, at press time, an investigation had been initiated to find and test any susceptible deer that came into contact with the index herd. Investigators were attempting to determine the source of the infection, and the NYSDEC was also conducting surveillance in surrounding wild deer populations.
The DEC is implementing precautionary regulations limiting transportation and possession of whole carcasses and some parts of wild deer taken near the location of the infected captive herds. The regulations will be similar to those currently in place for importation of carcasses and parts of deer into New York.
For the latest on the investigation, visit www.agmkt.state.ny.us/AI/cwd.html.