Chronic wasting disease has a long lifespan in the natural environment


Chronic wasting disease (CWD) is difficult, if not impossible, to eliminate.

The debilitating neurological disease that kills deer and other deer was discovered at a domestic deer farm in Avoca in the fall of 2018. The Quebec government recently reported that efforts to prevent the disease from spreading to the wild population of white-tailed deer have been successful. The measures taken by the wildlife management authorities included the creation of a valued management area in the Laurentians and Outaouais regions where hunting regulations were relaxed in order to reduce the deer population.

However, it is impossible to completely eliminate CWD from nature, if it exists.

Microscopic prions that contain CWD can remain infectious for several years in the natural environment, according to the Quebec Ministry of Forests, Wildlife and Parks (MFFP). A statement from press relations representative Catherine Ippersiel explained that the longevity of the MDC prion is unknown, but the prion from scrapie, a similar disease that affects sheep, has been shown to be alive for over 16 years old. Plants can take up CWD prion from contaminated soil through contact with infected deer or their droppings, urine, or blood. The plants take up the prion and can transmit the disease to other deer that eat the plants.

The MFFP does not consider as “significant” any contamination of soil or plants in the natural environment outside the Avoca farm. No positive samples from wild deer or other deer in the area have been found, which means that the possibility of the natural environment becoming present in the natural environment due to contact with wild deer is limited. .

The incubation period of MDC is long. According to the MFFP, infected animals typically take 16 to 36 months to show signs of disease, and tests have generally been ineffective in detecting CWD in animals infected for less than 12 months. In the region surrounding the Avoca farm, the MFFP will continue to maintain a low density deer population, the pursuit of enhanced surveillance to detect any emergence of cervid encephalopathy in the natural environment and the maintenance or improvement of measures to prevent new cases of the disease. For example, there are already regulations on the movement or possession of parts of deer slaughtered near the affected farm.

Wildlife biologist Dr Keith Munro confirmed the MFFP’s claims and supported the actions it has taken. Munro works for the Ontario Federation of Fishers and Hunters (OFAH), which represents hunters and recreational fishers across the province.

“We don’t really know how long this lasts,” Munro said of the longevity of CWD prions in the environment. He said there is no effective way to remove CWD from the wilderness.

Munro said the response from Quebec authorities was important to prevent CWD cases in domestic deer from spreading to wild white-tailed deer.

“If you have cases, you have to respond very quickly,” he said.

CWD was first detected in 1967, and there has never been a case in wild deer in Ontario. However, the mule deer at the Metro Toronto Zoo died of an unspecified disease in the 1970s. Tissue samples from these deer were re-tested many years later and found to be CWD.

Domestic deer breeders in Quebec are subject to the same animal welfare and licensing regulations as other breeders under provincial law. Municipalities can, however, regulate the breeding of domestic deer using local zoning laws. In 2019, Grenville-Sur-La-Rouge effectively made deer breeding impossible by limiting it to a very small portion of the municipality and requiring that deer always be inside a barn.

The Ontario Ministry of Natural Resources and Forestry created a new CWD program in December 2019, using feedback it received from OFAH. It restricts the movement of live and domestic deer in Ontario.


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