Chronic Wasting Disease – History in Alberta

In 2023-24, we tested 3,801 wild cervids. Of these, 3,758 were suitable for testing. Overall, CWD was detected in 708 wild deer, elk and moose (18.8% overall: 576 mule deer (365 males, 211 females), 112 whitetails (92 males, 20 females), 13 elk (4 males, 9 females), 7 moose (2 males, 5 females).

Looking more closely at the data for 2023-24, CWD was found in:

• 30.5% of 1,884 mule deer
• 7.9% of 1,417 white-tailed deer
• 5.8% of 224 elk (primarily from CFB Suffield)
• 3.1% of 223 moose (primarily from CFB Wainwright)

In 3,291 deer for which gender or sex was reported, CWD was detected in:

• 42.3% of 870 male mule deer
• 20.5% of 1,011 female mule deer
• 9.8% of 937 male whitetails
• 4.2% of 473 female whitetails

CWD was detected in only one Wildlife Management Unit where it was not previously documented (WMU 334). However, the prevalence (% infected) of CWD continues to rise in most areas, particularly in mule deer males, and at CFB Wainwright.

In 2022-23, we tested 4,614 wild cervids. CWD was detected in 714 wild deer, elk and moose (15.8% overall: 575 mule deer (361 males, 214 females), 129 white-tails (105 males, 24 females), 5 elk (all females), 5 moose (4 males, 1 female).

• 23.4% of 2,457 mule deer
• 8.3% of 1,556 white-tailed deer
• 1.6% of 320 elk (primarily from CFB Suffield)
• 2.9% of 175 moose (primarily from CFB Wainwright)

In 4,022 deer for which gender or sex was reported, CWD was detected in:

• 34.5% of 1,045 male mule deer
• 15.2% of 1,407 female mule deer
• 10.3% of 1,002 male whitetails
• 4.7% of 548 female whitetails

Patterns in the data in 2022:

CWD was detected in only one Wildlife Management Unit where it was not previously documented (WMU 312). However, the prevalence (% infected) of CWD continues to rise in most areas, particularly in mule deer males, and at CFB Wainwright.

In 2021-22, we tested 10,909 wild cervids. CWD was detected in 1,156 wild deer and elk (10.4% overall: 984 mule deer (594 males, 390 females), 164 white-tails (134 males, 30 females), 8 elk (1 male, 7 females).

• 14.4% of 6,816 mule deer
• 4.4% of 3,738 white-tailed deer
• 2.4% of 333 elk (primarily from CFB Suffield)
• 0 of 173 moose
• 0 of 16 other wild cervids, most of which were caribou

In 10,501 deer for which gender/sex was reported, CWD was detected in:

• 22.1% of 2,685 male mule deer
• 9.5% of 4,097 female mule deer
• 5.4% of 2,500 male whitetails
• 2.5% of 1,224 female whitetails

Patterns in the data in 2021:

CWD continues a steady progression westward, particularly along the Bow river corridor northwest of Calgary. It was detected for the first time in ten WMUs on the western and northern perimeter of the CWD area.

In 2020 we tested 8,905 heads. CWD was detected in 927 animals (10.4% overall: 755 mule deer (521 males, 234 females), 167 white-tails (133 males, 34 females) and 5 elk (1 male, 4 females). CWD was not detected in moose in Alberta this year.

• 14.8% of 5,089 mule deer
• 5.0% of 3,357 white-tailed deer
• 1.8% of 285 elk (primarily from CFB Suffield)
• 0 of 135 moose
• 0 of 39 other wild cervids, 22 of which were caribou

In the 8,429 deer for which gender/sex was reported, CWD was detected in:

• 20.5% of 2,537 male mule deer
• 9.2% of 2,542 female mule deer
• 5.3% of 2,497 male whitetails
• 4.0% of 853 female whitetails

Patterns in the data in 2020:

CWD continues to spread and was detected for the first time in 12 WMUs on the western and northern perimeter of the affected area in Alberta.

In 2019 we tested 10,400 heads:

• CWD was detected in 1,160 animals (11.2% overall: 986 mule deer (769 males, 217 females), 169 white-tail (155 males, 14 females), 3 elk (2 male, 1 female) and 2 moose (1 male, 1 female):
  • 17.5% of 5,632 mule deer
  • 3.9% of 4,295 white-tailed deer
  • 1.3% of 231 elk (primarily from CFB Suffield)
  • 0.9% of 232 moose (primarily from CFB Wainwright)
• In the 9,877 deer for which gender/sex was reported, CWD was detected in:
  • 24.5% of 3,133 male mule deer
  • 8.8% of 2,485 female mule deer
  • 4.8% of 3,226 male whitetails
  • 1.4% of 1,033 female whitetails
• Patterns in the data in 2019:
  • In many cases in eastern Alberta, the gender- and species-specific prevalence is much higher in individual Wildlife Management Units (WMUs).
  • CWD was detected in 10 WMUs where CWD was not previously known to occur, bringing the total to 53 WMUs with at least one documented CWD case.

In 2018 we tested 7,866 heads:

• CWD was detected in 579 individuals (7.4% overall): 506 mule deer (398 males, 108 females), 70 white-tailed deer (62 males, 8 female), and three female elk. In breaking down the sample, CWD was detected in:
  • 12.0% of 4,222 mule deer
  • 2.3% of 3,070 white-tailed deer
  • 0.8% of 361 elk (primarily from CFB Suffield)
  • 0 of 204 moose (primarily from CFB Wainwright)
• In the 7,269 deer for which gender/sex was reported, CWD was detected in:
  • 17.8% of 2,236 male mule deer
  • 5.5% of 1976 female mule deer
  • 2.7% of 2,307 male whitetails
  • 1.1% of 750 female whitetails
• Patterns in the data for 2018:
  • In many cases in eastern Alberta, the gender-and species-specific prevalence is much higher in individual WMUs than in previous years.
  • CWD was detected in five new Wildlife Management Units (WMU) in the vicinity of Cold Lake, Mundare, Two Hills, Vauxhall, and Vulcan. This indicates further geographic spread of CWD along major waterways.
  • CWD was detected in three cow elk from WMU 732 (Canadian Forces Base Suffield).
    • Since 2012, we tested 2,334 elk from WMU 732 and detected CWD in five (0.2%).

In 2017 we tested 6,340 heads:

• CWD was detected in 327 individuals (5.2% overall): 281 mule deer (220 males, 61 females), 45 white-tailed deer (44 males, 1 female), and one female elk. In breaking down the sample, CWD was detected in:
  • 8.2% of 3417 mule deer
  • 1.8% of 2489 white-tailed deer
  • 0.4% of 229 elk (primarily from CFB Suffield)
  • 0 of 198 moose (primarily from CFB Wainwright)
• In the 5,903 deer for which gender/sex was reported, CWD was detected in:
  • 12.4% of 1778 male mule deer
  • 3.7% of 1639 female mule deer
  • 2.5% of 1739 male whitetails
  • 0.1% of 747 female whitetails
• Patterns in the data for 2017.
  • The disease continues to expand westward into central Alberta.
  • CWD was detected in seven new Wildlife Management Units (WMU) in the Red Deer/South Saskatchewan/Bow and Battle river watersheds, adjacent to previous cases. This indicates further geographic spread of CWD westward along major waterways.
  • The expanded distribution brings CWD in the vicinity of Tofield (WMU 242) in the north and Strathmore (WMU 156) in the south.
  • CWD was detected for the first time in a wild cow elk from WMU 732 (Canadian Forces Base Suffield).
    • Since 2012, we tested 2117 elk from WMU 732 and detected CWD in two (0.1%).

In 2016 we tested 5,112 heads:

• CWD was detected in 179 individuals (3.5% overall): 154 mule deer (119 males, 35 females) and 23 whitetails (17 males, 6 females), one unknown deer, and one male elk. In breaking down the sample, CWD was detected in:
  • 5.4% of 2833 mule deer
  • 1.5% of 1494 white-tailed deer
  • 0.2% of 431 elk (primarily from CFB Suffield)
  • 0 of 176 moose (primarily from CFB Wainwright)
• Patterns in the data for 2016.
  • As in previous years, CWD occurs primarily in mule deer: 154 of 179 cases (86%).
  • The ratio of infected males to females wherever CWD occurs generally is ~2:1; however, in Alberta a greater preponderance of CWD occurs in males of both deer species. Ratios are closer to 3 or 4 :1. In addition, the overall prevalence (=% occurrence) of the disease in mule deer males (8.1% in 2016, n=1473 males tested) is significantly higher than in mule deer females (2.6%, n=1349).
• Overall, the disease continues to expand further westward.
  • New areas of CWD detected further west on the Red Deer River in WMU 158, on the Battle River in WMU 230, and on the Vermillion River in WMU 254.
  • These units are adjacent to previous cases and indicate further geographic spread of CWD along major waterways.
  • However, the finding of CWD in a white-tailed deer in WMU 250 northeast of Fort Saskatchewan is a significant westward extension of the known occurrence in the North Saskatchewan River watershed.
  • We also detected CWD for the first time in a wild elk:
    • A bull elk from WMU 732 (Canadian Forces Base Suffield).
    • Since 2012, CWD found in 1 of 1,973 (0.05%) elk from WMU 732.
    • However, CWD is well established in mule deer and white-tailed deer outside CFB Suffield along the Red Deer and South Saskatchewan rivers.

In 2015 we tested 4,929 heads:

• CWD was detected 116 individuals: 105 mule deer (77 males, 27 females, 1 unknown gender) and 11 whitetails (7 males, 4 females). In breaking down the sample, CWD was detected in:
  • 2.4% of the total number of heads tested
  • 3.8% of 2756 mule deer
  • 0.8% of 1420 white-tailed deer
  • 0 of 487 elk (primarily from CFB Suffield)
  • 0 of 135 moose (primarily from CFB Wainwright).
• An overview of the 2015 results reveals both expected and unexpected patterns in the data.
  • As in previous years, CWD occurs primarily in mule deer: 105 of 116 cases (90.5%).
  • The ratio of infected males to females wherever CWD occurs generally is ~2:1; this pattern also occurs in Alberta. However, the overall prevalence (=% occurrence) of the disease in mule deer males (5.9% in 2015) is significantly higher than in mule deer females (2.0%).
• Overall, the number of cases and rate of CWD positive deer in the annual sample continues to rise each year.
• The geographic distribution of CWD in eastern Alberta continues to expand. The disease occurs in local areas from the North Saskatchewan River watershed in the north to the Milk River in the south.
  • New areas of CWD detected in 2015: west of Cypress Hills in WMU 116, westward expansion in the parklands of east central Alberta (WMUs 158, 166, 238, and 242), and southeast of Elk Point in WMU 500.
  • Further evidence of CWD around Canadian Forces Base (CFB) Suffield and the Cypress Hills. However no CWD was found in CFB Suffield, despite testing over 1500 elk harvested in WMU 732.
• The most remarkable new case is the outlier in WMU 242 approximately 100 km further west than the closest known cases (in WMU 232 and 203). This was a mule deer buck harvested on the northern edge of the Battle River watershed west of Miquelon Lake and approximately 30 km southeast of Edmonton. Although CWD is well-established in eastern reaches of the Battle River, the case in WMU 242 significantly expands the known distribution of CWD in central Alberta. Cumulatively we have tested 700 deer heads from the Battle River watershed between WMU 242 and WMU 203/232 and all were negative for CWD. Thus, until we have data to show otherwise, the case near Miquelon Lake appears to be an outlier.

In 2014 we tested 4,163 heads:

• CWD was detected 86 individuals: 74 mule deer (59 males, 15 females) and 12 white-tails (all males). In breaking down the sample, CWD was detected in:
  • 2.1% of the total number of heads tested
  • 3.61% of 2048 mule deer
  • 1.13% of 1062 white-tailed deer
  • 0 of 131 moose
  • 0 of 909 elk
• An overview of the 2014 results reveals both expected and unexpected patterns in the data
  • As in previous years, CWD occurs primarily in mule deer: 74 of 86 cases (86.0%).
  • The ratio of infected males to females wherever CWD occurs generally is ~2:1; but in 2014 the ratio in the Alberta sample was ~5:1 (71 males, 15 females). The reason for the unexpected increase in the proportion of infected males is unknown, particularly since almost equal numbers of male and female mule deer, the species at greatest risk, were tested in 2014 (n = 1040 and 1065, respectively).
• Overall number (86 cases) and rate (2.1%) of CWD positive deer in 2014 are significantly higher than in previous years.
• The geographic distribution of CWD in eastern Alberta continues to expand. The disease occurs in local areas from the Battle River watershed in the north to the Milk River in the south.
  • New areas of CWD detected in 2014: Hand Hills area northeast of Drumheller in WMU 160, Bow River watershed (east of Lake Newell) in WMU 142
  • Further evidence of CWD around Canadian Forces Base (CFB) Suffield and the Cypress Hills. However no CWD was found in CFB Suffield, despite testing over 870 elk harvested in WMU 732.
• The disease remains well established in areas directly adjacent to the Saskatchewan border and continues to expand into WMUs further up the affected watersheds, primarily the Battle, Red Deer, and South Saskatchewan rivers.

In 2013 we tested 3,667 heads:

• CWD was detected 49 individuals (42 mule deer, 7 white-tailed deer; 34 males, 15 females). In breaking down the sample, CWD was detected in:
  • 1.34% of the total number of heads tested
  • 1.99% of 2107 mule deer
  • 0.59% of 1185 white-tailed deer
  • 0 of 117 moose
  • 0 of 212 elk
• As in previous years, there was a strong predominance of disease in mule deer and males. Also, CWD is clustered in local populations in specific areas and on specific watersheds.
• The disease continues to expand its distribution in Alberta and was detected in three Wildlife Management Units (WMU) not previously known to contain CWD.
  • There was a westward extension up the Red Deer River into WMU 160 (near Dorothy, Alberta).
  • Three cases were in WMU 118 - the first cases south of the Cypress Hills and the first cases in the Milk River basin.
  • CWD was documented in WMU 148 for the first time.
• The remaining CWD-positive deer were associated with the watersheds of the Red Deer, South Saskatchewan, and Battle rivers in the general vicinity of previous cases.

The 2012 program completed tests on 3402 heads:

• CWD was detected in 35 individuals (26 mule deer, 8 white-tailed deer, one moose). In breaking down the sample, CWD was detected in:
  • 1.03% of the total number of heads
  • 1.4% of 1829 mule deer
  • 0.6% of 1373 white-tailed deer
  • 1 of 13 moose
  • 0 of 165 elk

• The occurrence rate of CWD in the surveillance sample is similar to that found during the 2011 seasons.
• CWD continues to expand in deer populations in eastern Alberta in the general vicinity of the border with Saskatchewan. Infected animals are found in two primary watersheds:
  • Battle River system in east central Alberta
  • Red Deer/South Saskatchewan river systems in southeastern Alberta
• Other patterns in the 2012 data include:
  • a recurrence of disease along the South Saskatchewan River (WMU 150)
  • expansion westward along the Red Deer River approaching Bassano Alberta (WMU 152)
  • a significant cluster of cases along Ribstone Creek northeast of Coronation, Alberta (WMU 202)
  • ongoing cases in the Battle River system approaching Castor and Killam, Alberta (WMU 203) as well as in Canadian Forces Base Wainwright (WMU 728 and 730)
• The total number of CWD cases detected in wild deer in Alberta since September 2005 is 162.

The 2011 program completed tests on 3195 heads:

• Of the heads tested, 1977 (62%) were mule deer and 1168 (37%) were white-tailed deer.
• Overall CWD occurrence was 1.03%; however, the case rate was 1.52% in mule deer and 0.26% in white-tails.
• CWD was detected in 33 deer: 30 mule deer (18 males, 12 females; 3 yearlings, 27 adults) and three white-tails (1 yearling male, 2 adult males).
• One case involved a road-killed deer; the remainder were hunter harvest deer.
• All cases were detected within the CWD risk area along the eastern border.
• CWD continues to move upstream on the Battle River, with a significant cluster of CWD in adjacent WMUs 202 and 203. Also, we documented the first known case of CWD in WMU 730 (EAST portion of CFB Wainwright).
• There was a significant resurgence of CWD in the South Saskatchewan River valley where previous disease control efforts were discontinued after 2008. And a second case was found in WMU 119 on the north slopes of the Cypress Hills.
• The total number of CWD cases detected in wild deer in Alberta since September 2005 is 127.

During the 2010 CWD surveillance period we tested 5062 heads (primarily deer heads) and detected twenty (0.4%) new cases of CWD in wild deer in Alberta:

• Of the heads tested, 3211 (63%) were mule deer, 1781 (35%) were white-tailed deer. The remaining heads tested were elk.

• Eighteen positive deer were mule deer: thirteen males, five females; two were white-tail males.
• Nineteen CWD-positive deer were harvested by hunters and were in very good to excellent body condition. One infected deer was a road-kill.
• Most (19 of 20, 95%) positive deer were adults. The remaining positive deer was a yearling in early stages of infection.
• Many of the infected deer were near previous known CWD cases, largely in the Battle River and Ribstone Creek drainages in the north and the Red Deer River drainage in the south.
• A cluster of infected deer was found north and west of Dinosaur Provincial Park in WMU 152 – a significant extension of the disease westward along the Red Deer River.
• Of particular significance, the positive yearling mule deer buck was the first case of CWD found in the North Saskatchewan River valley in Alberta. This is strong evidence of recent expansion of the disease into or within the valley.
• As anticipated, additional infected deer were found in CFB Wainwright in association with the Battle River valley.
• The total number of CWD cases detected in wild deer in Alberta since September 2005 is 94.

During the 2009 CWD surveillance period we received and tested 4816 heads for CWD, primarily heads of hunter-killed deer and elk.

Similar to the pattern seen in other jurisdictions, mule deer and older-aged bucks in Alberta are proportionally more likely to be infected with CWD. The disease appears to be spreading deeper into Alberta.

• Twelve new cases of CWD were detected:
  • 11 of 12 (92%) were mule deer
  • 9 of 12 (75%) were adult males
  • The remaining positive was a white-tailed male.
• All positive deer were adults harvested by hunters and were in very good to excellent body condition.
• CWD was detected in three new WMUs (200, 202 and 119) and somewhat distant from previous known cases.
• New outlier cases were detected north of Jenner (well up the Red Deer River at the west end of WMU 151) and northwest of Elkwater (WMU 119).
• The total number of CWD cases detected in wild deer in Alberta since September 2005 is 74.

CWD was detected in a wild moose south of Medicine Hat. This is the first report of CWD in this species in Canada. The moose died as a result of a vehicle collision but was tested as part of Alberta's ongoing CWD surveillance program.

In January 2009, winter CWD control programs were suspended until further notice despite new cases of CWD detected in the 2008 and 2009 fall hunter surveillance.

The geographic distribution and incidence (rate) of new cases increased in the 2009 fall hunter sample.

A 2-part program (our 1-2 punch) combining fall hunter surveillance with subsequent winter response was applied. Disease control efforts were delivered in February and March around new cases of CWD detected during hunting seasons in the previous November and December.

Winter control programs generally found and removed three times more infected deer than the fall hunter surveillance, and provided focused local herd reduction in places where the disease was known to occur.

Enhanced surveillance upstream on the Red Deer and South Saskatchewan rivers, in addition to herd reduction around the previous cases of CWD was applied between January and March 2006. In conjunction with staff from Saskatchewan Environment, limited herd reduction also was conducted east of Empress.

From the 1439 deer collected in Alberta, CWD was confirmed in 7 wild deer in the vicinity of Empress and Acadia Valley along the Alberta-Saskatchewan border.

• Two additional cases of CWD were found in the 298 deer collected in Saskatchewan.

From the fall 2006 hunting seasons, 2 hunter-killed deer near Edgerton and Chauvin, along with one near Empress, were confirmed with CWD.

• These were the first 2 cases of CWD found in north central Alberta along the Alberta-Saskatchewan border.

In late March and April 2005, the Fish and Wildlife Division collected deer from a small high risk area east of Chauvin (including Dillberry Lake Provincial Park) near the Alberta-Saskatchewan border (CWD was known to occur in wild deer in the adjacent area of Saskatchewan). 

• This was Alberta's first herd reduction program.

The program was designed to enhance the surveillance sample in this area and initiate reduction of the high local deer density. All 486 deer collected were negative for CWD.

On September 2, 2005, CWD was confirmed in an emaciated mule deer found in a farmyard near Acadia Valley in southeastern Alberta along the eastern border.

• This was the first wild deer found to have the disease in Alberta.

In September and October 2005, 162 deer were collected in the vicinity of the infected deer at Acadia Valley. A further 2 cases of CWD were found in the area north of the Red Deer River.

In response to finding CWD on 2 game farms in central Alberta, the Fish and Wildlife Division sampled wild deer in the vicinity of the farms in late February or early March 2003.

All 320 deer and elk collected were negative for CWD. Ongoing hunter surveillance in the area from fall 2002 to fall 2005 did not detect any evidence of CWD in wild deer.

In late March 2002, CWD was identified in a farmed elk in Alberta. The infection was detected as part of Alberta's provincial surveillance program that began in 1996.

Federal CWD eradication programs were implemented immediately. All farmed cervids that moved on or off the premises in the previous 3 years as well as the current animals on the farm were killed and tested.

• No further CWD was found.

In early November 2002, CWD was identified in a farmed white-tailed deer in Alberta.

• As with the farmed elk, federal control and eradication programs were implemented immediately.
• One additional case of CWD was found.

In response to the first report of CWD in a wild mule deer in Saskatchewan early in 2001, the Fish and Wildlife Division collected 241 wild deer along the Alberta-Saskatchewan border in April 2001. All deer collected were negative for CWD.