A year and a half after chronic wasting disease was found in a White Sands deer, a state wildlife disease specialist says he is feeling more at ease about the safety of New Mexico game animals.
Kerry Mower said that’s because 18 months of testing have revealed only six cases of the mysterious and deadly neurological disorder, all in deer confined to the White Sands Missile Range/Organ Mountains area in southern New Mexico.
“After all that testing, we did not find chronic wasting in any new areas,” Mower, a state Game and Fish Department specialist, said last week. “With that data in hand, I can be a little more positive with hunters in the field.”
The positive news might explain why only about half as many hunters brought in the heads of their kills for testing this hunting season compared with the previous season.
“Part of the novelty and concern (about the disease) has worn off,” Mower said. “That’s consistent with what other states are experiencing.”
But Mower does not want New Mexico to let its guard down. He said Game and Fish will be revving up an information campaign to try to get hunters more actively involved in the testing process.
Chronic wasting disease is one of the 10 prion diseases, maladies in which outlaw proteins chew holes in the brain. CWD attacks deer and elk and is always fatal.
Mad cow is also a prion disease. News of a mad cow case discovered in the United States last month has overshadowed chronic wasting in recent weeks. But CWD remains the most prevalent prion disease in this country, having been found in at least 12 states.
It spreads among deer and elk herds but is not believed to infect humans – although people are cautioned to avoid eating the brain, nervous tissue or lymph glands from the animals.
New Mexico’s six diseased deer – no infected elk have been found here – remain the most southerly cases of chronic wasting disease in this country. The first sick deer was killed on the White Sands Missile Range in March 2002, but it was June of that year before tests confirmed CWD in the animal.
How the disease got to southern New Mexico remains a mystery, as does practically everything about prion diseases.
But since the first New Mexico case was detected, the Game and Fish Department has been testing animals throughout the state.
“We captured 20 deer up near Chama in July and late November,” Mower said. “We have gone down to White Sands and collected 30 more deer to test. In March, we are going to collect some more down in White Sands.
“We are hoping by summer we will have captured 60 or more deer and fitted then with radio transmitter collars.”
Test samples are obtained from hunters who bring in the heads of elk and deer, from roadkill and from sick animals killed by Game and Fish personnel.
Elk must be dead in order to collect the tissue needed for testing, but New Mexico has been using a live-test option for deer, an animal whose population is already on decline in the state.
“Live testing takes more effort and is more expensive and less efficient,” Mower said, “but the department is still committed to live testing rather than wholesale extermination. Our instructions are not to do any depopulation. That’s not even on the plate.”
The live-test process calls for deer to be sedated and lymphoid tissue removed from the animal’s tonsils and from beneath the deer’s eyelid. After the tissue is removed, the deer is fitted with a radio collar and released.
Benefits to this method include sparing the animal’s life and the chance to gather information about how the disease spreads using radio collars.
“If a deer tests negative now but becomes positive later on, the fact we were able to track it might give us some insight into the disease,” Mower said.
Down sides include the effort, the expense and the fact that it’s an imprecise science.
Mower said about 50 percent of the live tests are inconclusive because not enough lymphoid tissue is collected.
“Getting tissue is not the problem,” Mower said, “but you don’t know if there are enough lymphoid follicles in the sample until you put it under a microscope. By that time, the deer is long gone.”