Scientists are growing concerned that chronic wasting disease could be transmitted from deer to humans

Every fall, millions of hunters across North America enter the forests and grasslands to hunt deer. During the winter, people eat venison steaks, sausages, and hamburgers made from venison.

But these hunters aren't just at the forefront of American tradition. Infectious disease researchers say they are also on the front lines of chronic wasting disease, which could pose a serious threat to public health.

This neurological disease is contagious, spreads rapidly, is always fatal, and is caused by misfolded proteins called prions. It is known to only infect members of the cervid family, including moose, deer, reindeer, caribou, and elk.

Animal disease scientists are concerned about the rapid spread of CWD in deer. Recent research suggests that barriers to human transmission may not be as strong as previously thought, and that disease-causing prions may be evolving to become more infectious to humans. It is shown.

Our response to this threat has been strengthened. Michael Osterholm said that in 2023, a coalition of researchers “bred together 68 different world experts on various aspects of CWD to explore what the future holds if there are spillovers to humanity and food production.” “We have begun a large-scale effort to really look at the challenges that arise.” , an infectious disease expert at the University of Minnesota and a leading expert on CWD.

“The main message is that we are completely unprepared,” Osterholm said. “If we saw a spill now, we would be in free fall. There is no contingency plan for what to do or how to follow up.”

The expert team is developing plans for potential outbreaks, with a focus on public health surveillance, testing capacity, prion disease diagnosis, livestock and wildlife surveillance, risk communication, education and support.

Despite concerns, there are no known cases of human infection, although tens of thousands of infected animals have been eaten by humans in recent years.

Many hunters have wondered how seriously to take the threat of CWD. “The predominant opinion I've come across is that no human being has this disease,” says John, author and founder of MeatEater, a media and lifestyle company focused on hunting and wild game cooking. Steve Rinella says:

They think “we're not going to worry about it because we haven't crossed the species barrier,” Rinella said. “If hunters get CWD, things will change dramatically.”

Other prion diseases also affect humans, including bovine spongiform encephalopathy, also known as mad cow disease, and Creutzfeldt-Jakob disease. Mad cow disease has killed more than 200 people, mainly in Britain and France. Some experts believe that Parkinson's disease and Alzheimer's disease may also be caused by prions.

CWD was first discovered in a captive deer in Colorado in 1967 and has become widespread ever since. He has been found in at least 32 states, four provinces of Canada, and four other foreign animals.

Prions behave completely differently than viruses and bacteria, making them virtually impossible to eradicate. Matthew Dunphy, director of the Chronic Wasting Disease Alliance, said experts are calling it “a disease from outer space.”

The symptoms are severe. The brain deteriorates and becomes spongy. Also known as “zombie deer disease,” the condition causes infected animals to stagger, drool, and stare blankly before dying. There is no cure or vaccine. And it's extremely difficult to eradicate, even with disinfectants, even with high heat, and even withstands autoclaving and medical sterilization.

Cooking does not kill prions, Osterholm said. Unfortunately, “cooking concentrates prions,” he said.

Although CWD is not known to have infected humans or livestock, Osterholm's group just received more than $1.5 million in funding for research, and experts are very concerned about both possibilities. There is. Because CWD can infect more parts of an animal's body than other prion diseases such as mad cow disease, it may be more likely to infect people who eat venison (if can be transmitted to humans).

Researchers estimate that thousands of infected animals are unknowingly eaten by hunting families each year, and that number is growing each year as the disease spreads across the continent. Although wildlife testing for CWD is available, the test is not widely used because it is cumbersome.

A major problem in determining whether CWD is affecting humans is the long incubation period. People who ingest prions may not develop the resulting disease until many years later.

Prions are very persistent in the environment. They remain in the ground for years and can even be absorbed by plants.

Because the most likely route of transmission is through people eating venison, prevention is focused on rapid testing of deer and other deer carcasses. Now, a hunter might drive a deer to a checkpoint and have a lymph node sample sent to a lab. Most hunters ignore the results because it can take him more than a week to get them.

CWD was first detected in the wild in Montana in 2017 and has now spread to much of the state. Despite warnings and free inspections, wildlife officials in Montana have not seen much of hunters' concerns. “We're not seeing a decrease in deer hunting because of this,” said Brian Wakeling, director of game management for the Montana Department of Fish, Wildlife and Parks. In 2022, Montana hunters killed about 88,000 deer. Only 5,941 samples were taken, of which 253 tested positive.

Experts believe rapid testing will greatly increase the number of animals being tested and help prevent the spread of infection.

Because of the importance of deer to indigenous peoples, several tribal nations in Minnesota are working with experts at the University of Minnesota to come up with ways to monitor and manage the disease. “Tribes must develop plans to manage and mitigate the impacts of CWD,” said Doug MacArthur, tribal biologist for the White Earth Nation. “This is to ensure that it is preserved for generations.” said in a statement announcing the program. (Other groups referenced are the Leech Lake Band of Ojibwa and the Red Lake Band of Chippewa.)

Peter Larsen is an assistant professor at the University of Minnesota College of Veterinary Medicine and co-director of the Minnesota Prion Research and Extension Center. “Our mission is to learn all we can about not only CWD, but other prion-like diseases, including Parkinson's disease and Alzheimer's disease,” he said. He said he was “studying the biology and ecology” of misfolded proteins. “How do prions move in the environment? How can we reduce the risk and improve animal health and welfare?”

Part of that mission is new technology to make testing faster and easier.

“Amidst all the doom and gloom surrounding CWD, we have a real solution that can help fight this disease in new ways,” Larsen said. “There is some optimism.”

KFF Health News is a national news station that produces in-depth journalism about health issues.