Chronic wasting disease was first discovered in 1967 in captive deer in Colorado. At first, it seemed like nothing was wrong, but over time, infected deer, or cervids, began to lose weight. They stumbled, drooled, and lost their fear of humans. They were infected by a misfolded protein called a prion. Since 1967, these prions have spread to 34 other states.
There is no cure and no vaccine. According to Colorado Parks and Wildlife, about half the state's herds have infected individuals.
"Chronic Wasting Disease, or CWD, is in a family of diseases known as transmissible spongiform encephalopathies, which is a very big term, basically meaning that your brain starts looking like a sponge. So it kills brain cells until there's like literal holes in your brain. The most famous disease in this grouping is mad cow or bovine spongiform encephalopathy. And so that one was famous, not only because there were millions of cows killed in the UK, but because it actually transferred to people. With CWD, this is the only disease in this category that's been found in free-ranging wildlife."
Dr. Krysten Schuler is an associate research professor at Cornell working in the wildlife health lab. She has been studying CWD since 2002. Although there hasn't yet been a human case, the infection is everywhere.
"When these prions are shed into the environment, they can be taken up into plant tissues. So they can actually stick to plants, but they can also be taken up into other tissues, including...they've tested corn, tomatoes, wheat. Everybody is concerned about eating deer, eating venison and the potential to have a human case because of that. But because the deer are out there on the landscape, shedding these prions onto plants, they're contaminating the environment. So that's not good for agriculture either."
Hunting season in Colorado starts in early September and continues through late November. To prevent the spread of CWD and collect data on infection rates, Colorado Parks and Wildlife has made head submission of any deer harvested during rifle season mandatory. Dr. Shuler says that heads, eyes, and spleens carry higher concentrations of prions in the body, but any part of an infected deer can shed them into the environment. Human activity, especially hunting, can unintentionally spread them for miles.
"I'm not that worried about scavengers or predators spreading prions as much as I am about people spreading prions, either hunters taking home the carcass and they put the meat in the freezer and then they throw the butcher scraps out back and think they're doing a nice thing for the wildlife, like that would be better put in just your household garbage and going to a landfill.
Then it would be moving those parts and pieces because the brain, the spinal cord, the eyes, the spleen, they have a lot of prions in them. So those aren't necessarily the parts that people are going to eat, but a lot of people like to do European mounts now. And so that's where it's just the skull and the antlers. So they cut off the head and then bring it home to take off all the flesh, and take out the brain, and that may end up wherever. So that could be a potential new source of prion movement. And then you have captive cervids where the industry does move animals quite a bit around the country. And there's a lot of states that have positive captive herds now."
Prions are not like bacteria or viruses. They are resilient and nearly impossible to destroy. Once they are in the environment, removing them is a monumental, if not impossible task. Dr. Schuler says the best way to eliminate the disease is to get ahead of it.
"New York stands out because it's the one example now of a state that has been able to eliminate it in the wild. And whether it was because the New York State Department of Environmental Conservation acted quickly and took the right steps to stop it, or because they got lucky, but those prions likely came in either through taxidermy activities or through captive cervids. If you can get it quickly before a lot of prions shed in the environment, that's your best course of action. Once it gets over about 1.5% prevalence, you can't do anything about it. The problems is that the public might not understand this is a disease control operation. And while, yes, it's very sad to have to kill these animals, you're trying to stop a disease that you know if you don't act now, there is no real stopping it because we don't have a vaccine. There's no treatment. It's always fatal."
Managing populations of wild animals is no small feat. Harvesting sick animals may seem counterintuitive, but without intervention, CWD could have widespread, devastating effects.
"There is evidence that it can affect populations. So if you are a hunter, this could have bigger impacts down the road, maybe not for hunters today. But when I would talk to people about this before, I'd say think about your grandkids and the speed with which we're seeing CWD increase in certain high-density deer areas. Now I'm like, think about your kids. This is moving faster than we ever thought it would.
For the general public, the wildlife agencies that have to manage CWD spend a lot of time and a lot of effort. on CWD. Some of them have to collect so many samples that they even pull in like the fish biologists to help them collect samples. It can be all hands on deck. That's money that's going to CWD. It really does impact the entire functioning of a wildlife agency."
Thankfully, the public does have a few tools at their disposal. Prions can be denatured with a 25% bleach solution that Dr. Shuler suggests hunters use on their instruments; and Colorado Parks and Wildlife does have a response plan that involves expanding testing and intervention where necessary. If you see a deer that may be sick, stay calm and report it to wildlife authorities. More information on testing, symptoms, and safety can be found at cpw.state.co
Copyright 2024 KDNK
