REGIONAL- Chronic wasting disease is a known fatal neurological disease of deer and other cervids such as elk, caribou, and moose—but are humans at risk of contracting the disease as well?
Scientists don’t have a definitive answer to that question, but research with monkeys that have contracted it and emerging novel strains of the agent that causes it raise the possibility that it could one day be transmitted to humans, with potentially devastating effects.
That’s why the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota is getting out ahead of the potential problem by spearheading a global initiative involving 67 experts from seven countries to develop contingency response plans in the event of a spillover of CWD to humans or non-cervid farm animals.
The work is funded by the Minnesota Legislature, administered by the Department of Natural Resources and led by CIDRAP and CWD Project Director Michael Osterholm and co-directors Jamie Umber and Cory Anderson.
The legislative effort was led by Rep. Rick Hansen, DFL-South St. Paul, who will be a member of one of the project’s work groups.
“I think the beauty of the CIDRAP proposal is you’ve got groups working on a variety of things, whether it’s human health, management, research, what’s happening with other species, so you’ve got wildlife health, public health and management,” Hansen said. “We have a lot more to learn.”
The Timberjay spoke with project co-director Anderson last week for more information.
“In 2019, CIDRAP launched our online CWD program to provide a kind of one-stop shop for CWD information,” Anderson said. “This project that was more recently funded builds off of that and focuses in a bit more on a collective effort putting together these contingency plans.”
“Scenario-based planning is really what we’re doing,” Anderson continued. “We’re bringing together these folks to talk about the current situation where CWD continues to spread and we have the potential for novel strains emerging and don’t necessarily know what that means as far as risk for potential interspecies transmission. What would be their concerns or what would we need to do if we did see a suspect or confirmed case in a non-cervid production animal like a cow or swine and then similarly with humans and so on?”
Having just gone through the COVID pandemic, in which much of the response was created as the disease was unfolding, Anderson sees planning for possible CWD spillover now to be essential.
“I think there’s a lot of merit and a lot of value in having a plan, having these conversations, as opposed to waking up and having a situation and we’re trying to come up with these plans on the fly,” he said.
An odd deadly agent
CWD presents a novel problem in no small part because of what causes it, prions.
A prion is an infectious agent composed entirely of misfolded protein. Prions do not contain DNA or RNA which are the usual genetic material found in living organisms and viruses, and therefore don’t replicate in the same way. When a prion comes into contact with a normal protein, it causes that protein to change form to become another prion. As prions build up they form fibrils and plaques which disrupt normal cell processes, ultimately causing cell death.
Prions are known to cause a variety of neurodegenerative diseases in mammals, including Creutzfeldt-Jakob disease in humans and bovine spongiform encephalopathy (BSE, commonly known as “mad cow disease”) in cattle. Prion diseases are fatal and currently there are no known effective treatments for them.
And mad cow disease provides a precedent for animal-to-human transmission of a prion-based disease. Different from its similarly named companion, variant Creutzfeldt-Jakob disease cases in humans are believed to have been contracted from the consumption of cattle products contaminated with the BSE agent, according to a U.S. Centers for Disease Control fact sheet. It is believed that it takes years for vCJD to develop after exposure, and it is always fatal.
There hasn’t been any documented case of CWD spilling over to humans, and Anderson stressed that it’s not inevitable that it will.
“We don’t want to imply that a spillover event is going to happen,” he said. “Given the situation on the ground where we see more exposure happening and thinking through what we don’t know about strains, it warrants more attention and preparedness. It’s not like we’re saying it’s going to happen, it’s just something we’re considering and preparing for.
One concern Anderson noted is that CWD prions do have different strains, somewhat similar to the variants of the COVID virus.
“These different strains can actually pose different risks as far as interspecies transmission,” he said. “We know that prion strains can evolve and change over time. Are they comparable to what we’re seeing now and what’s the risk associated with that? That’s a lingering question that no one really knows the answer to. We have enough data to show that some of these strains might pose a higher risk than others, we just don’t have a great way of characterizing what that risk actually looks like.”
Project components
From the public’s perspective, CWD has been viewed as largely an issue for wildlife management experts. CIDRAP’s collaborative project will bring far more disciplines together to develop contingency plans for its potential transmission to humans.
Representatives from 18 universities, four U.S. federal agencies, seven state agencies, and four tribal communities, including members from the U.S., Canada, France, Germany, Norway, Spain, and the U.K. will be brought together in five distinct working groups, each addressing a different aspect of the situation. Those groups include:
• Human medicine and public health surveillance, epidemiology, laboratory capacity, planning and response.
• Cervid and production animal surveillance, laboratory capacity, planning and response.
• Prion disease diagnosis.
• Carcass and contaminated item disposal.
• Wildlife health and conservation.
The project will draw on CIDRAP’s past experience in developing roadmaps to deal with diseases like influenza, coronaviruses, and zika, Anderson said.
“This isn’t exactly a direct comparison,” he said. “But it’s the same sort of precedent. Thanks in large part to the funding provided by the legislature, we felt we had the template for bringing together folks who are leading the charge in their respective areas. You have extremely intelligent bench scientists, some of the leading prion researchers, then of course you have wildlife agencies working on it, a lot of different regulatory agencies. There’s not necessarily a disconnect, but a lot of these conversations haven’t happened or been thought out in this way.”
And a driving mantra for the effort to create contingency plans, Anderson said, is a favorite phrase of Osterholm’s in his public health work.
“Hope is not a strategy,” Anderson said.