Primates developed Chronic Wasting Disease after consuming tainted meat in an experiment, giving heft to Wyoming Game and Fish Department advice to test game meat from suspect hunt areas.
The experiment led by the Canadian Food Inspection Agency resulted in transmission of CWD from cervid (moose, deer and elk) meat to primates — cynomolgus macaques monkeys. The monkeys were infected by both an injection into the brain and by CWD-infected muscle fed into the stomach via a tube.
The findings suggest that primates could potentially contract the fatal disease simply by eating meat from infected animals. It was previously suspected transmission could only occur through handling or consuming tainted brain tissue.
There’s no known transmission of CWD from cervids to humans, the agency Health Canada said. However, a transmission path is now possible, according to preliminary findings that have not been peer-reviewed.
“These findings suggest that CWD, under specific experimental conditions, has the potential to cross the human species barrier, including by enteral (intestinal) feeding of CWD infected muscle,” Health Canada reported.
CWD, caused by a misshaped protein called a prion, is similar to mad cow disease (BSE) and the human cousin, Creutzfeldt–Jakob disease. All cause degeneration of neurological tissue and systems, among other fatal problems.
What does Wyoming do?
Some big game hunting seasons are underway in Wyoming, and the WGFD continues to offer free CWD testing of animals along with expedited testing for $30.
“We’ve had quite a discussion about this in light of the new research,” Wyoming’s Chief Game Warden Brian Nesvik told WyoFile on Tuesday. “We recommend folks test their animal in those areas where we know CWD has been found.”
Maps of CWD-positive areas for various species are available on the Game and Fish website.
“If somebody tests an animal [and it’s positive] we just recommend folks don’t eat that meat,” Nesvik said. “We stuck with that.”
The recommendation is consistent with guidelines from the Centers for Disease Control and World Health Organization, he said.
Health Canada said that despite the news of the experiment and its advisory, it was not changing its warnings about CWD. That warning recommends “avoiding consumption of foods from known infected or any diseased animals and taking precautions when handling cervid carcasses.”
Further, Health Canada says warnings “should be provided to groups who may be expected to have higher exposure to cervids through hunting and diet (e.g. rural and Indigenous populations).”
Wyoming Game and Fish also recommends hunters not kill animals that appear to be infected with CWD. There’s no known cure for the family of diseases, and all are ultimately fatal.
“Up front we ask people not to harvest those animal that look sick,” Nesvik said. Infected animals appear listless, skinny, can have drooping ears, can drool, and wander in circles.
But behavioral observations are no guarantee of the status of an animal, he said. “The majority of CWD-positive animals that are harvested appear completely normal.”
Hunters who kill an animal must abide by game laws that require the retrieval and preservation of edible parts, regardless of the animal’s appearance. Hunters must have proof of infection — the results of a test — before they can discard meat. “They would need to have some kind of a confirmation [that] something was wrong with the animal,” Nesvik said.
Game and Fish enforces a number of regulations regarding the transport of animal parts from positive areas, all of which can be found on the department’s website. Among the rules are that the brain and spinal column not be moved from areas where CWD is known to exist.
In the U.S. in 2007 nearly two thirds of those surveyed said they had eaten venison or elk meat, according to the CDC. “If CWD could spread to people, it would most likely be through eating of infected deer and elk,” the agency says. “Strongly consider having the deer or elk tested for CWD before you eat the meat.”
WHO says “no tissue that is likely to contain the BSE [Bovine Spongiform Encephalopathy] agent, nor part or product of any animal which has shown signs of a TSE [Transmissible Spongiform Encephalopathy] should enter the (human or animal) food chain.” That means infected meat or animal parts should not be fed to livestock.