Deer Tests Positive for CWD at White Sands
A mule deer collected from the White Sands Missile Range has tested positive for Chronic Wasting Disease and the director of the New Mexico Department of Game and Fish declared an Animal Health Emergency Tuesday, closing the state to any importation of deer or elk.
Director Larry Bell said the positive test was confirmed Monday, June 17, by the Wyoming State Veterinary Laboratory. This is the first positive test for CWD in the state of New Mexico.
The disease is a transmissible spongiform encephalopathy (TSE), a neurological disease that is always fatal to deer and elk. It has been found in free-ranging deer and elk in Colorado, Wyoming, Nebraska, Wisconsin, South Dakota and the Canadian province of Saskatchewan.
CWD has been more commonly found on or near game farms, although there are no such facilities near White Sands Missile Range.
"We are closing the borders to the importation of cervids because Chronic Wasting Disease has been identified here and we want to isolate it and prevent its spread," Director Bell said. Game ranches have been identified as a source of CWD and now that the disease has been discovered here, the state must take all steps to prevent any additional outbreaks or infection.
"New Mexico and all other states are trying to find ways to shore up their importation regulations as we search for a means of managing and preventing CWD," Bell said. Other states that have banned or restricted the importation of deer species include: North Carolina, Michigan, Vermont, Tennessee, Texas, Nebraska, Wisconsin, New York, Colorado, Arizona and the province of Alberta.
Although Tuesday's actions only restrict the importation of live deer and elk, Bell said the state soon may be discussing regulations to restrict the importation of sport-harvested deer and elk. There are no known cases of CWD infecting humans or livestock, although New Mexico and other states do encourage hunters to follow precautions when handling dead game.
Kerry Mower, a wildlife disease specialist for the Department, said this case will shake the world's current understanding of Chronic Wasting Disease because it is so far away from game farms and other accepted avenues of CWD transmission.
"We do not know how CWD was transported to the White Sands area," Mower said. "There are no game farms down there and it is far from the endemic areas of Colorado and Wyoming. But this does illustrate how little we know about the spread of transmissible spongiform encephalopathies."
The disease is found most commonly in neurological tissues - brains, spinal cords, eyes, lymph nodes - of infected animals. New Mexico, like other states, has been testing the brain stems of deer and elk for several hunting seasons, trying to determine if CWD was present. The brain samples must be taken within 48 hours of the animal's death. The diseased deer was collected March 28 by White Sands Missile Range game wardens. The shortage of CWD testing facilities nationwide and the number of states submitting samples accounted for the delay in receiving results.
Infected animals become emaciated, drink water to an excessive degree and lose control of bodily functions including balance.
"This deer was just skin covering a rack of bones," Mower said. The Department will initiate sampling of more deer as soon as possible to determine the range and extent of infection. Even though CWD is not known to occur outside the deer family, the Department will begin testing some oryx on White Sands. "We are immediately prepared to deal with a hundred or more samples," Mower said.
The Department already has submitted 140 samples for testing this fiscal year.
It is difficult, although not impossible, for TSEs to jump from one species to another. There is no evidence that CWD can be transmitted to humans or livestock, but as a precaution the Department of Game and Fish does advise hunters to not consume any neural tissue of animals they kill and to wear latex gloves when field dressing dead animals.
There are no practical or proven tests to determine if CWD is present in living wild animals. Portions of each brain stem must be removed and examined under a microscope, although a test of deer tonsils is being developed. It would be impossible, however, to adequately capture and extract tonsil tissue from New Mexico's statewide deer population.
In infected animals, microscopic lesions appear in infected brain tissue. Either a loss of neurons in the brain or the accumulation of proteinaceous, infectious particles, or prions, cause the lesions. Prions are believed to be the cause of TSEs.
Chronic Wasting Disease is the name for this disease when it occurs in deer and elk, but other species suffer similar maladies. The TSE in domestic sheep is called scrapie and it's bovine spongiform encephalopathy (mad cow disease) in cattle. This type of disease has several names when it occurs in humans: Creuzfeldt-Jakob Disease, kuru, new variant CJD, Gerstmann-Straussler-Scheinker syndrome and fatal familial insomnia.
The Department will continue to sample the heads of deer and elk killed during the coming fall hunting seasons. As an incentive for hunters to cooperate, those who submit heads within the 48-hour period will be entered in a drawing for oryx and Valle Vidal elk hunting authorizations. In addition, the agency is developing an action plan for dealing with CWD, although at this point Director Bell does not anticipate the killing of thousands of animals as other states are doing.
"I am, however, prepared to take any action necessary to protect the state's resources from the spread of Chronic Wasting Disease," he said.
For more information about Chronic Wasting Disease, call Kerry Mower at (505) 476-8080.