Regional investigators are closely watching for any signs of a new outbreak of a highly contagious and deadly disease that has decimated feral rabbit colonies in Edmonton and Calgary.
Rabbit Bleeding Disease is a sudden, highly contagious and fatal viral disease of European wild and domestic rabbits, including most breeds preferred as household pets.
The virus is almost always fatal to European rabbits, including domesticated breeds.
However, the currently prevalent RHDV-2 strain affects both domestic and wild rabbits.
Wildlife experts are watching for the potential spread from feral populations of domesticated rabbits to the native species of Alberta rabbits and hares.
The virus spreads rapidly through the colony, causing organ damage and internal bleeding.
The mortality rate for the virus is between 70 and 100 percent with most infected rabbits dying within days. Often, the only signs of infection are sudden death and bloody noses.
The Canadian Food Inspection Agency said infected rabbits usually develop symptoms within one to five days.
“Death is common soon after illness. Death may also occur suddenly without signs,” says CFIA.
The disease “spreads rapidly” in an infected colony, said Margo Pipes, a wildlife pathologist with the Alberta Fish and Wildlife Foundation and a University of Alberta professor.
“It is very lethal to rabbits and rabbits in Europe,” she said. “All feral rabbits, domestic rabbits, are disappearing from the area.”
While the risk is considered minimal among wild species, Bibus said, there is the potential for it to spread to domestic species of rabbits and hares.
Pybus predicts that the virus will kill feral rabbit colonies too quickly to have a chance to reproduce through native species such as hares and funeral animals.
In Edmonton in the fall of 2021, the virus killed a colony of about 30 rabbits who had lived at Holy Cross Cemetery for more than three decades.
Last month in Calgary, three separate colonies in the Manchester industrial area in the southeast of the city were infected. Within two weeks, most of the feral rabbits were gone.
A single mountain cottontail was found among the dead feral rabbits.
He tested positive for the virus and is the first documented case of the virus affecting a native wild species in Alberta since the province’s first case was discovered in Tapper in March 2021.
So far, Bibus said, there is no evidence of a widespread spread of the wild species in Alberta.
She said the risks of transmission to wild species are highest in communities, such as Canmore, Alta, where there are wild populations of domesticated rabbits.
The city has had a rabbit problem for years and relies on a winter trapping program to help keep the population under control.
Between January and April of this year, 288 feral rabbits were culled. This is an increase from the previous year when 180 feral rabbits were trapped.
“The disease can spread among these populations and it is rapid and fatal,” Beebus said.
“And if those rabbits live and share the same space with snowshoe hares or big rabbits, that’s where they are most worrisome.”
“Canary in the Coal Mine”
RBD virus has been present in European rabbit species since the 1980s but wild species in Canada, the United States, and Mexico have not been affected.
That changed in 2010 when the new strain RHDV-2 was identified in France. The disease survived in captive rabbits and spread in both wild and wild populations.
The first reports of RHDV-2 outbreaks in North America occurred in Quebec in 2016, British Columbia in 2018, and Washington state in 2019.
Beginning in early spring 2020, cases were seen in wild jackrabbits and cottonwood species in the southwestern United States and northern Mexico for the first time.
To date, fatal cases have been confirmed in wild species including black-tailed jackrabbits, antelope Jackrabbits, desert cottontails, mountain cottons, and eastern cottontails in various western states.
“This was the first time we’d seen a form of this virus that was able to infect wild species, so it was a whole new ball game,” Bibus said.
She said the province will continue to monitor wild species of rabbits and any deaths will be investigated extensively among feral populations.
“The hares are the canary in the coal mine for us,” she said.
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