An international study to learn about potential human health risks associated with chronic wasting disease started May 1.
Stefanie Czub of the University of Calgary’s faculty of veterinary medicine and a senior pathologist with the Canadian Food Inspection Agency is leading the five-year, $5 million project.
The Canadian-German study hopes to learn more about the progressive, fatal disease that affects cervids such as mule deer, moose, white-tailed deer and elk and the potential for infecting humans who eat venison.
The research group comprises scientists from Lethbridge, Calgary and Germany. Government financial support comes from Canada, Germany and the Alberta Prion Research Institute.
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Scientists suspect the disease is spread between animals, making it different from classical BSE, which is believed to be transmitted through feed containing contaminated meat and bone meal.
The study will infect some non-human primates with CWD tissue through feed and others by surgically implanting the infection in their brains.
The animals will be housed in a German research centre because a similar facility does not exist in Canada, Czub said.
Last year, Czub headed a project in Lethbridge in which young elk were infected with CWD to track the disease’s progression.
The best case scenario is for the primates to remain healthy.
“We don’t really anticipate a rather short incubation time. With the elk, they came down with the disease in a matter of months, which was anticipated.”
The project may have to be extended because it could take longer for the disease to appear, especially among those eating infected venison.
There is little evidence that CWD is transmitted between species.
The Centers for Disease Control and Prevention in Atlanta, Georgia, studied 10 people who died of a disease similar to Creutzfeld Jacob disease. They were either avid hunters who ate venison or were known to have eaten a lot of venison.
“None of these 10 cases were infected with variant Creutzfeld Jacob disease or anything like that. They were all different brain diseases,” Czub said.
CWD is known to exist throughout North America and appears in free ranging deer, elk and moose. The CFIA is also monitoring caribou for possible infection.
The European Union tested 20,000 deer and elk heads for CWD last year with no positive cases.
It has been known as a wasting disease since 1965 and was thought to be connected to pneumonia because the animals drooled and drew foreign material into their lungs.
Wild animals may die undetected and be consumed by scavengers, making it difficult to accurately determine the disease’s prevalence.
Tests on canine species show no indication they can be infected.
Other cross species tests have been done with prion diseases.
Scrapie, which affects sheep and goats, was tested on primates. It took 65 months after they were infected to show clinical signs. They did not develop the itchiness associated with scrapie in sheep.
Instead, they showed odd behavior and neurological problems with trouble moving and rising.
When mice or hamsters are infected with scrapie, they do not exhibit itching but do develop neurological symptoms.
Other species such as mink and cats can also develop spongiform encephalopathy.
Cats develop BSE from eating infected meat but mink are being studied in the United States because they appear to have the atypical form of BSE.
Studies at a Wisconsin mink ranch revealed the presence of the disease in 1985. The farmer indicated he fed them downer cattle.
After the mink were skinned, the carcasses were fed back to the mink and the disease was perpetuated. There were no new outbreaks once this was stopped.
“They are very sure that it is atypical BSE,” Czub said. “That also means there was atypical BSE most likely in the United States much earlier than we initially thought.”
