U of M to fund more CWD research in Minnesota’s deer herds

Jeremy Schefers runs CWD testing at the University of Minnesota.
Jeremy Schefers runs chronic waste disease testing at the University of Minnesota in February 2019.
John Enger | MPR News 2019

Researchers at the University of Minnesota have been working on a rapid testing system to detect chronic wasting disease for more than a year. The goal is to develop a test that will determine whether a deer is infected with the fatal disease. The next step is to determine how the deer got infected in the first place. 

CWD has infected huge swaths of Wisconsin’s deer herds. Now it has a foothold in southeastern Minnesota — threatening the state’s half-billion-dollar hunting industry.

Nearly $250,000 from the University’s Minnesota Futures program will partially fund a new research project designed to get a much more precise idea about how the disease spreads. 

“This isn’t like studying a hog farm,” said ecology professor Eric Seabloom, who is leading the research, “where a disease just rips through a relatively simple system. When CWD spreads in the wild, you’re looking at thousands of organisms in an incredibly complex natural system.”

Chronic wasting disease is spread from deer to deer through direct contact, but the faulty brain and nerve proteins, called prions, that cause the disease can also end up in water and plants. 

In Crow Wing County, where only one wild deer has tested positive for chronic wasting disease, deer carcasses are incinerated. It’s incredibly expensive and would be hard to scale up if the disease were to spread across more of the state. But local leaders believe it’s worth it, to prevent any chance of the prions spreading.

Red dye used in the testing process only sticks to the misfolded proteins
Red dye used in the testing process only sticks to the misfolded proteins, called prions, that cause chronic wasting disease.
John Enger | MPR News 2019

That’s because prions are believed to be incredibly robust: If a deer infected with CWD dies and is eaten by wolves, and those wolves travel 40 miles and relieve themselves on a certain patch of grass, and then another deer eats that grass, prions from that first digested deer can, in theory, infect the second deer.

At least, that possibility has been shown in lab experiments. It’s yet to be tested in the wild. 

“That’s an important part of science,” Seabloom said. “Showing that something is possible in the lab. But the next step is, you have to quantify it. How likely is it?”

Researchers have discovered that prions can float, unchanged, in pond water for at least six years, Seabloom said. But if a deer drinks that water, what are the odds it will get infected? Right now, researchers don’t know for sure. 

Seabloom will be working with a handful of professors from other fields. For their first experiment, they’ll mix CWD-infected deer brains with soil from around the state, and grow plants in it, so they can measure how many prions are drawn up into the leaves. 

And though it might look like basic gardening, Seabloom said there’s some urgency behind the work. 

Scientists have long been worried that CWD could one day infect humans. In nonscientific terms, the faulty deer prions don’t yet have the right shape to affect humans. But diseases can mutate. Many scientists believe it could happen in CWD, but there has never been a confirmed case in humans. 

Now, with COVID-19’s well-publicized leap from animals to humans, Seabloom said the idea is on everyone’s minds. 

If CWD ever makes the same leap, he said, it will be especially important to understand how prions move in the natural world, and where they exist in Minnesota’s environment.

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