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Reducing the prevalence of chronic wasting disease in Manitoba

Natasha Kumar By Natasha Kumar Jan31,2024

Reduction in the prevalence of chronic wasting disease of deer in Manitoba

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Two white-tailed deer during the rutting period, in a field north of Winnipeg. (Archive photo)

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Of more than 4,000 cervid samples tested by Manitoba during the 2023 hunting season, only 4 had chronic wasting disease. This makes provincial biologist Richard Davis optimistic that the disease will be contained.

I am always optimistic. I think we're on the right path to reducing transmission, slowing it down. As to whether [the disease] has become endemic or not, I'm not sure, says Mr. Davis, who is a wildlife health biologist with the Manitoba government.

In 2021, the province discovered chronic wasting disease of deer for the first time in its territory. That year, five infected mule deer were identified. This species is more likely to carry the disease than white-tailed deer.

In 2022, the province has detected 17 cases of the disease in mule deer, and 2 infections among white-tailed deer. The positive cases were located in particular in two places along the border with Saskatchewan, as Richard Davis explains.

We have not seen any new positive cases in [the area where the first infected animal was identified], Dropmore. This is promising, and there are only three positive samples in the southwest. That too is promising, continues the biologist. The samples mainly come from animals killed by hunters.

These three new positive cases are in two male mule deer and a male white-tailed deer, located in an area of ​​a few kilometers, where there have already been positive samples. Mule deer, particularly males, are more likely to transmit the disease.

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We believe we have good control of this mule deer herd. The two white-tailed deer in this area could simply be overflows from mule deer carrying the disease, explains Mr. Davis.

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A head of a mule deer, the species most likely to be infected with chronic wasting disease, in the Dauphin wildlife laboratory. (File photo)

Mule deer are a protected species in Manitoba, but last year the province issued hunting licenses to mule deer for the first time in decades, in order to reduce the population. In 2022-2023, hunters submitted more than 400 mule deer samples.

This year there were only 80 samples. This suggests that we were effective in reducing the population and capturing animals that were sick, says Richard Davis.

Now, the province plans to conduct a drone survey to determine the number of mule deer and white-tailed deer in areas where the disease has been detected. Richard Davis says that, depending on the outcome of this survey, the province could undertake very localized culls.

Our main goal, going from before, it is to continue our localized control of the disease […] and at the same time to work on preventive measures of the effect of humans on transmission, indicates the biologist.

Moving carcasses and feeding deer accidentally or intentionally contributes to disease transmission. Richard Davis also emphasizes that it is necessary to ensure that the deer population remains relatively low, in particular through hunting, to limit the spread of chronic wasting disease.

The discovery of an infected female white-tailed deer near Winkler dampens Richard Davis' optimism. This new case is in a part of Manitoba with no previous detection.

We found this female white-tailed deer south of Winkler, near the North Dakota border. That’s 200 kilometers from any known positive cases in Manitoba and outside the province. This is an anomaly. That’s a long distance for a white-tailed deer to travel. It's not unheard of, but it's very strange, says Richard Davis.

For this animal to be infected, it suggests that there could be other infected animals in this area, he continues.

He notes that the number of samples from this region has been relatively high in recent years, which makes this discovery all the more surprising. “It’s a big question for us, we don’t know what happened,” he said.

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Richard Davis, Manitoba wildlife health biologist, in one of the Dauphin Wildlife Lab offices. (Archive photo)

The animal in question was young, approximately 2 and a half years old, according to the province's analysis.

We are still trying to determine how to respond. There are not many tools in the fight against wildlife diseases. We have carried out culls in the past, but the idea of ​​culling deer to protect their health is not ideal, adds Richard Davis.

Currently, there is no test to determine whether a living deer has chronic wasting disease.

We are thinking of doing an aerial survey. We would go in a helicopter to count all the deer in that area, find out where they are, where they congregate, what the population is. We are also thinking of installing radio collars to understand their movements in the region, continues the biologist.

This year, the hunters only had to wait on average between six and eight weeks to find out if the animals they slaughtered were affected by the disease.

In an area along the Saskatchewan border and along the U.S. border, hunters must submit the heads or guts of deer they kill to the province so it can test for chronic wasting disease.

The mandatory sample submission area was expanded after the disease was discovered in Manitoba in 2021. ;at the time, it could take up to six months to get a test result over the past two years.

Decreasing the number of samples from 6,000 to 4,000 – something Richard Davis attributes to a reduction in the deer population due to two harsh winters – helped reduce wait times.

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Deer heads litter the ground at the wildlife laboratory in Dauphin, Manitoba. (File photo)

The province also allowed hunters to collect lymph nodes from deer themselves this year.

< p class="StyledBodyHtmlParagraph-sc-48221190-4 hnvfyV">We have received over 400 samples collected by hunters. So almost 10% comes from hunters and that’s fantastic for us. I like to imagine that instead of one laboratory taking 4000 samples, we would have 4000 laboratories taking one sample, says the biologist.

The Dauphin wildlife laboratory collects retropharyngeal lymph nodes from deer heads and sends them to laboratories across Canada. Until this year, there was no laboratory in Manitoba capable of performing this analysis.

We had the good fortune to partner with the Public Health Agency of Canada and its national microbiology laboratory in Winnipeg. He doesn't normally do this kind of testing, but he wants to do some research analysis on it. So we started a partnership, we sent him samples, and that quickly accelerated things, says Richard Davis.

Chronic Wasting Disease deer is a prion disease like Creutzfeldt-Jakob disease. For now, these diseases are fatal and incurable, in both humans and deer.

Although there is no proof transmission of chronic wasting disease to humans, Health Canada recommends not eating meat from an infected animal.

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Natasha Kumar

By Natasha Kumar

Natasha Kumar has been a reporter on the news desk since 2018. Before that she wrote about young adolescence and family dynamics for Styles and was the legal affairs correspondent for the Metro desk. Before joining The Times Hub, Natasha Kumar worked as a staff writer at the Village Voice and a freelancer for Newsday, The Wall Street Journal, GQ and Mirabella. To get in touch, contact me through my 1-800-268-7116

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