CWD spreading slowly in northwest Kansas

Pratt, Kan. -
Chronic wasting disease remains rare among the Kansas deer population - much rarer than epizootic hemorrhagic disease, which exhibits remarkably similar symptoms, and there's no evidence that CWD can be transmitted to humans. So why are Kansas Wildlife and Parks Department scientists concerned by the 10 confirmed cases from the 2009 hunting season and a presumptive 11th?

"Diseases can evolve and change. That's where the danger comes," said Shane Hesting, wildlife disease coordinator for Wildlife and Parks. "(And) we need to be concerned about CWD because we can't do anything about it."

CWD is a member of the group of diseases called transmissible spongiform encephalopathies (TSEs). Other diseases in this group include scrapie in sheep and goats, bovine spongiform encephalopathy (BSE or Mad Cow Disease) in cattle, and Cruetzfeldt-Jacob disease in people.

A variant Cruetzfeldt-Jacob disease can occur in humans who consume tissue of the spinal cord or brain of cattle infected with BSE. Wildlife and Parks and the Kansas Animal Health Department are closely watching both wild and captive deer populations because of the possibility, however remote, that chronic wasting disease might one day make the leap from deer, elk and antelope to humans.

Like mad cow disease, CWD is almost always fatal. Two years may pass before infected animals display any symptoms, and worst of all, the infectious agent, proteins called prions, can survive in soil for years. Animals begin shedding prions into the environment within a few months of becoming infected. The number of prions shed is about equal to the number of prions present in the body when the animal finally succumbs to the disease.

"It's very stable," Hesting said. "It takes extreme temperatures to kill it. Right now, we don't really have anything to disinfect soil that won't kill everything else too."

Researchers are working on a more environmentally friendly disinfecting agent, Hesting added. In the meantime, Wildlife and Parks is relying on the slow spread of the disease and the cooperation of hunters, taxidermists and the ranchers who raise captive populations to contain CWD.

All of the confirmed cases of CWD from the 2009-2010 hunting season are from northwest Kansas.

"It means what we thought it was going to mean," Hesting said. "A few years, spreading out slowly from a central hot zone in Decatur County. We haven't done any vigorous testing to confirm this, but it appears to be going slowly south and east."

In total, 2,702 animals were tested for CWD, including 16 elk, 278 mule deer, and 2,408 white-tailed deer. Although the agency has completed testing of its target sample for this hunting season, biologists are still collecting heads from road-killed deer in northwest Kansas. In addition, the agency is collecting road-killed deer in Harper County, near an area where a captive elk herd had to be destroyed in 2001 because of CWD.

Annual testing is part of ongoing effort by KDWP to monitor the prevalence and spread of CWD. The fatal disease was first detected in a wild deer taken in Cheyenne County in 2005. Three infected deer were taken in Decatur County in 2007 and 10 tested positive in 2008, all in northwest Kansas.

Hesting estimated from the testing that 1 to 2 percent of wild white-tail deer in Decatur County are infected with CWD. Wild herds in Colorado and Nebraska have much higher rates of prevalence, he said - 20 to 30 percent in some areas.
Captive populations can contribute to the spread of the disease, Hesting said. He encouraged anyone raising deer or elk to take part in the certification program of the Kansas Animal Health Department.

Hunters can do their part by taking their kills to taxidermists who are part of the KDWP testing program or by taking carcasses to landfills. Hunters should also avoid transporting carcasses far from where the animal was killed.

"We're trying to come up with a solution to allow hunters to bone out deer in the field," Hesting said. Currently, hunting regulations require keeping most of the carcass intact until it is processed.

Hunters should always avoid killing an animal that appears sick in any way. CDW is characterized in its later stages by emaciation, stumbling, lowered head and loss of fear of humans. Never consume any part of an animal that appears disease.

Any sick deer should be reported to KDWP.

The Kansas Department of Wildlife and Parks contributed to this story.