Meat from deer contaminated with chronic wasting disease may be more dangerous than originally thought, according to ongoing research conducted by Stefanie Czub, of the Canadian Food Inspection Agency, and the University of Calgary.
So far, results are available from five animals, according to a release from the CFIA. At this point, two animals that were exposed to CWD by direct introduction into the brain, one that was administered infected brain material orally and two that were fed infected meat all have become infected with CWD.
“The ‘supposed’ resistance of macaques was about the only prop remaining in the complacency wall (macaques’ genetics are closer to ours than squirrel monkeys, which also can contract CWD), but this is just the tip of the iceberg,” said Darrel Rowledge, director of the Alliance for Public Wildlife, in an interview with Josh Honeycutt of Realtree’s Brow Tines and Backstrap blog. Rowledge was one of those who presented on CWD at the Deer Summit in Texas. “The implications to markets are enormous, and governments here may have finally begun to take notice.”
CWD is a sister disease to bovine spongiform encephalopathy, or BSE — the infamous “mad cow disease” that killed 229 people in the United Kingdom — and is an incurable, always fatal degeneration of the brain, according to an analysis published by the Alliance for Public Wildlife. It was first documented in captive mule deer in the late 1960s.
Estimates show 7,000 to 15,000 CWD-infected animals are being consumed by humans every year, according to the analysis, and these sort of prior diseases are known for jumping between species barriers.
“Results of CWD laboratory challenges of non-human primates are mixed,” the analysis said. “CWD transferred readily to squirrel monkeys orally (92 percent), but macaques, which are genetically closer to humans than squirrel monkeys, have demonstrated significant resistance, even to direct intracerebral injection. It should be noted, however, that recently macaques were shown to be susceptible to scrapie, but only after an extended, silent incubation of ten years.”
The disease was declared a state of emergency in 2001 by then-U.S. Secretary of Agriculture Ann Veneman, and the APW says every factor of CWD has only increased since that declaration.
Concerns from hunters
Tim Donges, president of the Quality Deer Management Association’s Bluestem branch, advocated for urgency by decision-makers after hearing the recent reports. Donges was among 30 speakers at the Deer Summit in Texas and said CWD was a hot topic at the event.
“I was in the meeting in Texas with Darrel Rowledge and he is very concerned about public safety,” Donges said. “Once the first human is thought to have contracted CWD, we could see fallout in the ag market because of food safety concerns. This is becoming a very serious situation. I do not see a way to stop the spread. The U.S. government has bought deer farms contaminated by CWD and are considered contaminated super sites.”
Donges said the government has tried several means of containing the disease, including radiation, burning the soil in furnaces and formaldehyde, with no success.
“CWD prion can be moved by wind blowing dust or rain water moving contaminated soil,” he said. “Scavengers such as vultures, crows, coyotes, mice, opossum, etc., can move the prions. I have seen a vulture in Kansas that was tagged by the U.S. Fish and Wildlife Service, it migrated from Venezuela to Marion County, Kan. Deer hunters could move contaminated carcasses from a CWD area such as northwest Kansas to another state or another part of Kansas and spread the disease. Captive deer farmers (could be) moving live infected deer. Prions can come up through plants and other animals or humans could digest it.”
He said he has suggested to the National Deer Alliance that the organization go to Washington, D.C., and lobby for implementation of the “Deer Hunting and Conservation Act,” which would pull in resources from the USFWS, the U.S. Department of Agriculture and the Department of the Interior to combat the disease.
“Currently, the NDA is trying to set up a meeting in Washington, D.C., but it is hard to get their attention,” Donges said. “They are busy fighting among themselves. This whole thing just makes me sick to the stomach. I am very concerned about where we are headed. It is a real possibility that the ‘deer species’ could be extinct decades from now. The hunters have no idea how bad this could get. Twenty-four states now have reported CWD. The population model suggests that some day we will no longer hunt ‘deer species.’ The best thing hunters can do at this point is to start having their deer tested for CWD prior to consumption in order to protect themselves until we can learn more. We should not be moving carcasses around to other parts of the state or country.”
Donges suggested that those wanting more information on the disease check out the CWD Alliance.
Contamination in Kansas
Shane Hesting, wildlife disease coordinator with the Kansas Department of Wildlife Parks and Tourism, said the state detected 12 animals with CWD in 2016-17, but these included 10 deer in the Northwest Zone, where CWD is between 9 percent to 20 percent prevalent in older males, and two deer along the eastern edge of Stafford County. The agency also is working with the QDMA to investigate reports dating back to last deer season of an uptick in a rare foot rot disease in Kansas deer that had mutilated and killed several deer, the testing results of which have yet to be released.
Hesting said the agency didn’t detect CWD in the Eastern Zone, which is the zone the KDWPT accepted hunter-harvested deer from this past season. The samples in other zones were from private submissions or sick/suspect animals.
He cautioned the public not to overreact to the results of the Canadian study, saying they hadn’t yet been officially peer-reviewed and published. He said a similar study in Colorado failed to produce disease through the feeding of CWD-infected meat, but noted that studies into the matter will continue.
“There is a risk with about everything we do,” Hesting said. “We have known for a long time (not new) that squirrel monkeys get clinical TSE (transmissible spongiform encephalopathies) disease from having CWD prions injected into their brains.”
The British Deer Society also issued a statement on June 8 regarding the differing research results.
“BDS is aware that researchers in Alberta have experimentally infected macaques with chronic wasting disease via oral gavage with infected cervid brain or muscle tissue,” the statement said.
“However, other researchers at the Rocky Mountain Laboratory have failed to infect macaques orally. These apparently contrary results suggest that more research is required to better understand the infection risk that infected deer products pose to primates.
“The European Food Safety Authority recently published a scientific opinion that stated that while there was no absolute barrier to transmission of CWD to humans, epidemiological studies of humans have not linked Creutzfeldt-Jakob disease to exposure to CWD.”
Hesting offered additional information regarding this coming deer season and last year’s surveillance. He said northwest Arkansas has a prevalence of about 20 percent, so the agency blanked the southeast part of Kansas with sampling and didn’t detect the disease this past season.
“Surveillance moves to the Southcentral Zone this coming season,” Hesting wrote in an email. “I have attached Kansas CWD distribution maps (this past season and the cumulative distribution of positives) and the CWD Surveillance Zone map. Make sure to pay special attention to my last paragraph.
Southcentral Zone samples will be collected and tested by KDWPT — up to 458 samples. Samples from hunters outside the Southcentral Zone would be private submissions and testing of those samples would have to be paid for by the hunters.”
Hesting said the agency’s goal is to test 458 samples from the Southcentral Zone this coming season. Hunters who harvest deer aged 2½ years or older in the zone can have their meat tested for free through the program. Those who hunt outside the zone still can have their deer tested for CWD, but the cost is $28 plus shipping and any supplies sent to the agency by Kansas State University, where testing is done on the meat.
Hunters harvesting deer outside the Southcentral Zone and wanting to have their deer tested should contact K-State at Clientcare@vet.k-state.edu or call (785) 532-5650 or (866) 512-5650.
To minimize their risk of exposure to CWD, hunters should:
* Consult with their state wildlife agencies to identify areas where CWD occurs and take appropriate precautions when hunting in such areas.
* Avoid eating meat from deer and elk that look sick or that test positive for CWD.
* Consider having the deer or elk tested for CWD before consuming the meat if the animal was harvested from an area known to have CWD-positive animals. (Information about testing is available from most state wildlife agencies.
* Wear gloves, bone-out the meat from the animal, and minimize handling of the brain and spinal cord tissues when field dressing an animal.
SOURCE: CENTERS FOR DISEASE CONTROL AND PREVENTION