In the shadow of the Rocky Mountains, thousands of gaunt white-tailed deer are stumbling to their deaths, victims of a mysterious and highly contagious ailment known as chronic wasting disease.

Biologists are working day and night to kill off the very animals that support a billion-dollar hunting industry. Game ranches are being forced to destroy their herds. Entire towns are losing their livelihoods catering to hunters.

If the right precautions aren’t taken, Maine could find itself in the same situation.

This week, the state departments of Agriculture and Inland Fisheries and Wildlife and representatives from the deer-farming industry agreed to place a six- month ban on the importation of deer or elk in an effort to protect Maine’s domesticated and wild deer herds. Maine is the last of the Northeastern states to enact such a ban.

“We all agree that under no circumstances do we want this disease to come into Maine,” Gerry Levigne, a state wildlife biologist, said Friday.

CWD has been present in Western states for 40 years, but its spread has recently accelerated, becoming a national concern. In just the past year, the disease has jumped both the Continental Divide and the Mississippi River, infecting herds in eight Western states and several Canadian provinces.

A few months ago, the infection appeared in Wisconsin’s white-tailed deer, 900 miles from any other known CWD problem. Officials in that state have no idea how their herd became vulnerable.

It was this most recent discovery that spurred officials across the country to action. The white-tailed deer population stretching from Nova Scotia to Minnesota is essentially one “metapopulation,” with no geographic barriers to divide it, Levigne said.

Without defensive action, the infection of Maine’s deer herd with CWD is “a virtual certainty,” the biologist said.

CWD and mad cow disease

Chronic wasting disease is one of a family of diseases in which rogue proteins called prions literally eat brain tissue, causing erratic behavior and eventually death.

Its relatives include scrapie, which infects sheep, BSE or mad cow disease, which infects cattle, and Creutzfeldt-Jakob disease, which kills humans. All are incurable, and none can be conclusively diagnosed without dissecting the brain of a victim.

CWD was first observed in mule deer at a Colorado research farm in 1967, but for more than a decade, biologists ignored what initially seemed like a digestive problem. Deer in the early stages of CWD lose their fear of humans and salivate excessively. They stop eating, lose motor control, and die.

When the strikingly similar mad cow disease made news in the 1980s, scientists took a second look at CWD.

The disease was shown to be more contagious than any of its cousins, which are spread only when one animal consumes the brain or spinal tissue of another infected animal – primarily through commercial feed, which often contains ground animal carcasses. Besides neurological tissues, urine, saliva and feces of CWD deer were all found to contain infectious prions.

Laboratory tests have also indicated that these diseases can jump between species. In response, some scientists have proposed that chronic wasting disease could be as dangerous to humans as mad cow disease, which has been linked to 100 deaths worldwide, including five in the United States, since 1995.

But whether eating venison, handling deer meat or hides, or even using hunting lures made from deer urine can cause the disease is not known.

In 1999, wildlife biologists were asked by the Centers for Disease Control to investigate the possibility that one victim of Creutzfeldt-Jakob disease had contracted the illness by eating contaminated venison while living in western Maine. Biologists inspected the brains of 300 deer from the region where she had lived, but found no evidence of CWD, Levigne said.

Wild white-tails

State biologists examine as many as 8,000 deer every fall, and have never observed the symptoms of chronic wasting disease, Levigne said.

“We have no knowledge of CWD in Maine, and no concerns about consuming deer meat,” he said. “It’s a pretty obvious and visible problem in a wild population. If we had it, we’d know about it.”

If CWD were to appear in Maine’s herds, however, the results would be disastrous.

Hunting, a $240 million business, would be decimated if deer hunters feared becoming ill from their venison.

And the state’s 240,000-deer herd might have to be destroyed to stop the spread of the disease.

“If CWD got into Maine, we would have to make a very difficult decision whether to eradicate the population,” Levigne said. “Either way, it would be a huge cost to the department.”

Deer farming

The most likely cause of infection in Maine would not be the slow cross-country spread of CWD among wild herds, but the deer-farming industry, which trades animals from state to state. Maine has 97 deer farms, and many have imported animals at one time or another.

The Maine Department of Agriculture conducts regular CWD tests at USDA slaughterhouses and has never found an infected animal. Additionally, states that have identified CWD outbreaks have been banned from selling animals to Maine since last May, said Shelley Doak, spokeswoman for the department.

But with an incubation period of up to three years, infected but healthy-appearing animals may have slipped through during the late 1990s.

“Time will tell,” Levigne said. “We can’t be certain that we don’t have some deer here already that are sleepers and will start showing symptoms in the next few years.”

The state Department of Agriculture oversees deer and elk farming, requiring vaccinations for other diseases and making regular farm inspections, Doak said.

With so many farms, however, the data aren’t as complete as some might like. The department estimates that Maine’s captive herds include between 6,000 and 8,000 deer, but it doesn’t have concrete data on what portion of these herds were imported from other states. Working with deer and elk farmers to obtain this information will be a priority of the department during the ban, Doak said.

“Every deer that is born will be accounted for and every deer that dies will be accounted for,” Levigne said.

The six-month ban also will give officials with the U.S. Department of Agriculture time to draft national strategies for halting the spread of CWD. Maine will likely take its cue from federal recommendations, and work with deer farmers to draft stricter regulations, department officials say.

“Keeping CWD out of Maine will depend on the full cooperation of each and every one of these farms,” Levigne said. “If they comply with the embargo, I’m very confident that we’ll keep it out.”

Misty Edgecomb is the outdoor writer for the NEWS, and can be contacted at medgecomb@bangordailynews.net.