Chronic wasting disease has been introduced to Southwest Colorado – along with questions about where the disease might spread next.
The announcement came last week, when Colorado Parks and Wildlife confirmed a deer found last spring east of Montrose, 100 miles north of Durango, carried the neurological disease.
Joe Lewandowski, Parks and Wildlife spokesperson for the southwest region, said the news isn’t alarming, in part because the disease spreads at a glacial pace. Most infected animals don’t exhibit symptoms for one to two years.
But, given the unknowns that enshroud the disease, questions will arise.
“We don’t have any way of knowing or predicting where it goes next. It’s accepted that if you find one deer with CWD, there are probably others out there,” Lewandowski said. “We don’t know that until someone sees and reports an animal that is sick, or a hunter harvests one, and we test them.”
The disease is borne from prions, or infectious proteins, and affects captive and free-ranging cervids by eroding the animals’ brain tissue, causing them to lose coordination and ultimately starve.
Southwest Colorado has evaded it until now, though the disease has been present in Colorado for more than 30 years.
Chronic wasting disease, which is thought to spread through the animals’ waste, is typically established within a geographic area and gradually spreads, or it appears seemingly at random, as it did in Arkansas in the past year.
Causes are unclear, but migration likely causes localized outbreaks, and human-assisted movement is a suspect behind random appearances, said Margaret Wild, a wildlife veterinarian for the National Park Service.
“One way it might spread is when people take the carcasses back to home states and don’t dispose of them in a way that prevents environmental contamination,” she said.
Kerry Mower, a wildlife disease specialist with the New Mexico Department of Game and Fish, said the agency closely watches chronic wasting disease developments in Colorado, particularly because a healthy deer population traverses an area between Durango and Navajo Lake.
“Deer and elk at our northern border move back and forth,” Mower said. “There is quite a bit of north-south migration between the states.”
Though the disease has been identified in two other areas of New Mexico – near the White Sands Missile Range and in the southern Sacramento Mountains – it hasn’t been found near the Colorado-New Mexico border.
That area is known to produce trophy animals and attracts hunters for that reason, Mower said, so he established a check station along a Forest Service road that accesses hunting territory. He asks hunters, who are mostly compliant, to take tissue samples from their kills.
Hunters are an asset to collecting information on the disease, wildlife officials said, because areas where hunting is prohibited rely on observation.
“Unfortunately, just looking for sick animals doesn’t tell you if the disease is not there, or how much is there,” Wild said. “Without that type of surveillance, it’s hard to say if the disease is a brand new introduction or if it’s been there a little while.”
Experts said they can’t draw conclusions between the disease’s spread and the season, as cervids tend to move year-round; in summer, they head to the high country or to protected areas where females can birth. In winter, they move to lower elevations and southward.
Colorado Parks and Wildlife is offering free testing for hunters who kill within Game Management Units 62, 64 and 65, all around Montrose, this fall. The cost for testing is $25 in other game units in the state.
Lewandowski said there are no plans at this time to require testing in Montrose or elsewhere in the state, but as a precautionary measure, hunters are encouraged to do so.
To date, chronic wasting disease has been detected in 77 of Colorado’s 186 game management units.