CWD concentrated in urban deer population, wildlife officials say
About 40 residents turned out for an update on the prevelance of chronic wasting disease in the Libby area Jan. 13. Roughly 13 in every 100 deer within city limits is likely to carry the progressive illness, state officials said. By contrast, 22 out of 600 deer in the Chronic Wasting Disease Management Zone tested were found to suffer from the affliction. (Duncan Adams/The Western News)
Testing indicates that CWD remains largely confined to the urban area of Libby, which gives state officials hope that they can contain the spread. (Paul Sievers/The Western News)
The bad news reported Jan. 13 by a wildlife official about the comparatively high prevalence of chronic wasting disease among deer within Libby’s urban environs offered one flickering hint of a silver lining.
Tissue sampling and related analysis suggest that the progressive, fatal neurological disease — affecting white-tailed deer, mule deer, elk and moose — is more concentrated within the city than in the Chronic Wasting Disease Management Zone that includes areas within about a 10-mile radius of the city.
“It seems to be fairly confined so far,” said Neil Anderson, wildlife program manager for Region One of the Montana Department of Fish, Wildlife and Parks.
“Hopefully, we can keep it that way,” he said.
The disease, which seems to spread primarily through contact among animals in the deer family, spreads more easily where the cervids are densely populated.
Anderson spoke during a meeting held by Fish, Wildlife and Parks at Libby City Hall to update residents on the agency’s sampling of tissue from deer, moose and elk in the region in recent months. Nearly 40 people attended the meeting, a tally that included several agency personnel.
Anderson said the sampling of 150 white-tailed deer from the Libby urban area determined that 20 of the animals tested positive for CWD. Analysis of this random sample suggests that roughly 13 of every 100 deer in the urban area are likely suffering from CWD.
In contrast, only 22 of 600 white-tailed deer sampled from the CWD Management Zone tested positive for the disease, he said, suggesting a prevalence percentage of about 3.7 percent.
Sampling in the management zone found one mule deer that was positive for CWD. And tissue from a moose taken just outside the zone also was positive for CWD. Twenty-one elk that were sampled were all negative for the disease.
Anderson said Fish, Wildlife and Parks will work with the city to address the deer population in Libby. And he said there could be an increased harvest of deer in the CWD Management Zone during the next hunting season.
“We’re not trying to eradicate deer,” he said. “We’re trying to lower the density. We’re not going to be able to eradicate CWD. It’s here. It’s established.”
CWD, as a neurodegenerative disease, affects the nervous systems of mule deer, white-tailed deer, elk and moose. From first infection until death can take as long as two years, Anderson said.
FWP and others have reported that there have been no documented cases of the disease affecting livestock or pets or animals outside of the deer family. Similarly, there are no confirmed cases of the disease being transmitted to humans, according to the Centers for Disease Control and Prevention.
Still, as Anderson reiterated, the Centers for Disease Control advised that “hunters should avoid eating meat from deer and elk that look sick or test positive for CWD.”
Tissues known to harbor the CWD agent, a protein known as a “prion,” include the brain, spinal cord, eyes, spleen, tonsils and lymph nodes.
Anderson and FWP colleague Dillon Tabish were asked whether mountain lions and other predators that prey on deer spread the disease. Anderson said it’s possible that the infectious prion can pass through a predator and be present in its scat.
Tabish said later that the prion likely would be too diluted to contaminate the soil and become a potential avenue for transmission.
“In fact, evidence has shown that predators, like lions and wolves, can help reduce the spread and prevalence of CWD because they target infected animals that are slower and weaker,” Tabish said.
“We are primarily concerned about human transport of infected carcasses and congregations of deer due to illegal feeding or natural feeding where disease is proven to spread at a higher rate,” he said.
Several people who attended the meeting raised concerns about the deer population in Libby. One man suggested FWP ought to stress that feeding deer is illegal and be more forceful in enforcement.
Anderson said managing deer in an urban environment is challenging. Trapping is most effective during the months when natural food sources are not as abundant in town, he said.
Tabish said trapping is the primary method of deer removal in urban settings. In Libby, 60 deer were trapped and killed last year. The meat of deer that were not infected by CWD was donated to families in need, he said.
Bob McLaury said FWP should focus more attention on the population in Libby, where the prevalence of CWD is higher and could be a source for infecting deer, elk and moose in the larger region.
“You guys need to get serious about this and knock that population down,” McLaury said.
Meanwhile, Anderson praised the efforts of locals who provided tissue samples to FWP from animals they had hunted. And he and Tabish said residents of the region are doing a good job of taking carcasses to the landfill instead of dumping them in forests and fields — where an infected carcass could add prions to the soil.