NISKU, Alta. – A leading expert on chronic wasting disease says it is highly unlikely cattle can get the disease from deer and elk.
“It’s extremely difficult to infect cattle with CWD,” Beth Williams of the University of Wyoming told a chronic wasting disease conference.
To find out which animals are susceptible to the disease, scientists gave a CWD agent to animals not likely to get CWD, including cattle, either by injecting it directly into their brains or administering it orally.
“Cattle that received a high dose of oral inoculant five and a half years after remain perfectly healthy,” she said.
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It’s important news to elk and deer producers, who sometimes feel ostracized by their cattle-producing neighbours worried the disease might cross the species barrier.
CWD is in the same group of transmissible spongiform encephalopathies as bovine spongiform encephalopathy in cattle, scrapie in sheep and goats, and Creutzfeldt-Jakob Disease in humans.
Glenda Elkow, president of the Alberta Elk Association, said the conference will have a major impact if it helps dispel some of the myths around the disease.
“If the conference explains the facts of what’s known about CWD and dispels the paranoia and hysteria, that’s good for everyone,” said Elkow of Lloydminster, Alta.
The natural hosts for CWD are mule deer, white-tailed deer, hybrid mule and white-tailed deer, and elk. Other cervid species such as red deer may be susceptible.
Williams said little work has been done on bison, but the few samples studied have not found evidence of the disease in that species.
During the study of unnatural hosts, cattle that received an inoculant directly into the brain remained healthy.
Cattle grazing with infected deer have also shown no evidence of getting the disease.
“It does suggest cattle are pretty resistant to chronic wasting disease,” Williams said.
The research on unnatural hosts also found that ferrets, mink and squirrel monkeys got the disease when injected with the agent directly into the brain. Not all mice got the disease, but some did.
Hamsters weren’t infected when a CWD agent from infected elk or deer was injected into their brains, but did get it if injected with a CWD agent from infected ferrets.
Sheep, goats and mule deer got the disease when the agent was injected directly into their brains. Mule deer, white-tailed deer and elk got the disease when administered orally, which researchers believe is a more normal route of transmission.
Coyotes don’t seem to be susceptible to CWD, but Williams doesn’t know if their role as scavengers is connected with the spread of the disease.
She said there are still no answers about where CWD came from. One theory is that CWD is a scrapie agent adapted to sheep.
“Very likely we will never know where CWD came from.”
Research done on CWD and humans has shown no direct link, Williams said.
