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Elk feces on Wyoming feedgrounds likely would transmit chronic wasting disease from sick to healthy animals when and if the disease makes it into northwest Wyoming’s herds, according to authors of a study published in the journal Nature.

The research shows how infected deer shed the disease’s infectious agent – called a prion – in their feces. The study gives some of the first evidence explaining how chronic wasting disease could be transmitted from animal to animal in the wild.

The study was conducted in a laboratory run by Stanley Prusiner at the University of California San Francisco. Prusiner won the Nobel Prize in physiology or medicine for discovering prions in 1997.

In the study, first reported last week in The New York Times, five deer were fed brain tissue from wasting-disease infected animals. Researchers collected the feces from the five deer at various times after they were infected but before the animals showed symptoms of the disease.

By seven to 11 months, researchers were able to use the fecal samples to infect mice genetically engineered to have characteristics similar to elk.

The evidence that chronic wasting disease is spread in feces likely has important implications for feedgrounds, said one of the study’s authors, Erdem Tamguney, an assistant professor of neurodegenerative diseases at UCSF.

“If you think of areas where these animals congest, you would find higher concentrations of feces in those areas,” he said. “Feedgrounds would be a very good way of spreading this disease. Sick and healthy animals come together.”

Tamguney pointed out that prions retain their ability to infect healthy animals for years, maybe even decades.

“Deer feces and elk feces are all over the place,” he said. “And prions can remain infectious in the environment for a long time.”

While earlier research shows lower rates of chronic wasting disease in elk herds than deer herds, the recent study is likely relevant to both species, Tamguney said.

“Elk seem to be as susceptible to CWD prions from deer as they are from elk,” he said. “There isn’t really much of a difference in this disease between elk and deer.”

Terry Kreeger, supervisor of the Veterinary Services Branch of the Wyoming Game and Fish Department, agreed that the research has implications for elk as well as deer.

“I think it’s directly applicable to elk,” he said. “If the same study was done using elk poop, I would expect to have the exact same result.”

Kreeger said deer and elk likely ingest infected feces during grazing, or possibly by inhaling an airborne form of fecal matter. He also said situations where elk are concentrated could lead to an increase in the disease.

“There would be more of a concentration of feces in an area where elk are concentrated for a long period of time,” he said. “It would be reasonable to assume that you could see higher prevalence of CWD due to the increased amount of fecal biomass.”

Still, Kreeger said the results come as little surprise. “We always thought that the feces could be a [transmission] route,” he said. “We’ve expected this for years. I don’t think it’s the only route.”

“Unfortunately, [the UCSF study] doesn’t really offer any management solutions,” Kreeger continued. “If this is the primary way that this disease is spread, nothing comes to my mind what we could do.”

Tom Roffe, chief of wildlife health for the U.S. Fish and Wildlife Service, said the research shows the need to phase out feedgrounds.

“We’ve known for a long time there is an environmental component to the transmission of CWD,” he said. “The research just gives you a final point where you could say yes indeed, what we thought was going to happen is going to happen. Anything that causes the aggregation of animals in contaminated environments should enhance transmission.”

Roffe said the decision to phase out feedgrounds should be an easy one for wildlife managers. If chronic wasting disease really does pose a threat to elk on feedgrounds, phasing out artificial feeding would help protect the herd’s health and avoid environmental contamination. he said.

“What are the consequences of being wrong?” he asked. “We actually start managing wildlife like wildlife.”  

And chronic wasting disease isn’t the only disease associated with fecal contamination on feedgrounds. Foot rot, a bacterial disease that periodically causes lameness in elk on the National Elk Refuge, isn’t caused by malnutrition, but by elk with cuts on their feet stepping on feces.

“It’s always in dirty, contaminated environments,” he said.

Roffe said wildlife managers need to make more habitat available, whether feedgrounds persist or not.

“We are now seeing what people are calling feedground-like behavior in nonfed elk,” he said. “Whether you do it by feeding or by creating little pockets of land that are refuge, you are exposing animals to sources of infection.”

National Elk Refuge Manager Steve Kallin said refuge officials are “very concerned” about soil contamination from the disease. “Which is one of the reasons we’re expanding our irrigation system to reduce the concentration of animals,” he said.

Refuge officials hope to add another 3,400 acres of irrigated land for a total of just over 5,035 acres to reduce the Jackson Elk Herd’s reliance on supplemental feed. “We want to avoid amplifying the infection rate by not concentrating animals nose to nose on a feed line.”

Kallin said the refuge is also taking other precautionary measures.  “As a standard practice, if we happen to see an animal that is exhibiting any neurological symptoms, we will remove that animal so we can test it and prevent the possibility of additional spread of prions,” he said. “We’ll continue to spread the animals out and utilize clean snow as much as possible.”

Lloyd Dorsey, Jackson representative for the Greater Yellowstone Coalition, called for a phaseout of feedgrounds.

“One of the characteristics of elk feedlots and irrigated plots is the very heavy accumulation – month after month, year after year – of feces,” he said. “These findings add additional emphasis to the need to get away from dense concentrations of elk associated with the feedlots. The science is clearer that decreased densities of vulnerable animals on native ranges rather than feedlots is the way we should be managing our big game herds.”

In October 2008, a moose in Star Valley tested positive for chronic wasting disease, marking the first time the disease has crossed the Continental Divide into an area near elk feedgrounds northwest Wyoming. There is no evidence that CWD can be spread from elk and deer to humans, though both the Centers for Disease Control and the World Health Organization advise hunters not to eat meat from CWD-infected animals.

Last week, state and federal officials announced they would increase efforts to look for chronic wasting disease this hunting season.

Wyoming representatives of Sportsmen for Fish and Wildlife did not immediately return calls for comment.