Evolving science | Research and policy have expanded and intensified since BSE was first discovered in Canada in 2003
The way the world thinks about and reacts to BSE has changed thanks to Canada’s experience and influence.
An international panel praised the country for its thorough inquiry and trace back after Canadian authorities completed their investigation into the first case reported in May 2003.
“It has really positioned Canadian science in a very visible and positive way,” said Brian Evans, who was chief veterinary officer for the Canadian Food Inspection Agency. He retired earlier this year.
“We had to change the international response to BSE,” he said.
“We had to change the international standards to be reflective of how the science had evolved over the previous 15 or 20 years and we had to change the way the global community responded to BSE, including the OIE (World Organization for Animal Health), which was in the process of developing a country recognition process. Canada was very involved in the original definition of BSE.”
There has been considerable government investment in research. A national network was established, and Alberta created its own $50 million initiative to support research into prion and prion-like diseases. Prions are the misfolded proteins that cause BSE.
The Alberta Prion Research Institute supports work into animal diseases such as BSE, scrapie and chronic wasting disease caused by aberrant prions, as well as human diseases such as Parkinson’s, Alzheimer’s, ALS, some temporal frontal lobe dementias and other neurodegenerative diseases connected to misfolded proteins.
Few Canadians knew about the disease when BSE was found in 2003. A core group of 12 now have specific expertise and another 35 research the diseases from various directions, said Kevin Keough, head of the institute.
Among those researchers is Dr. Stefanie Czub, who heads the prion, pathology, virology and wildlife disease lab at Agriculture Canada’s research centre in Lethbridge.
Her research is now focused on atypical BSE, a different type of disease than the classical form seen in most of the infected Canadian cattle.
“The question is, of course, how does this occur,” said Czub of the atypical form.
“Is this related to feeding and contaminated feedstuffs and things like this?” she said.
“There are not very many cases in the world, 65 in total. Canada has two of these cases, and the United States, these are their only cases, three of these atypical cases.”
Animals infected with atypical BSE behave differently from those with the classical form.
Czub is investigating whether the atypical form can be transmitted by feed, and whether removal of specified risk material in slaughtered animals is a sufficient safeguard.
Researchers are also puzzled why only one animal is ever found in a herd that presumably ate the same feed. Worldwide, fewer than five percent of the cases involved more than one animal from the same herd.
Czub said a genetic link similar to that of scrapie in sheep and chronic wasting disease in cervids is a possibility.
“But we have no really scientific data and information that there is a genetic resistance or a genetic susceptibility to BSE, but it almost seems like that.”
Researchers also have questions about how long BSE has been around.
Keough said scientists do not know whether BSE was present in the cattle population in a spontaneous form before it was first observed in England nearly 30 years ago.
“The BSE problem began to be observed in the early to mid ’80s, but that doesn’t mean some of the downers that have been out there previously didn’t have it,” he said.
“When you are not looking and you have a one in a million occurrence, you don’t notice it.”
It’s possible that a few British cattle with a spontaneous form of the disease were rendered and put into the feed system, resulting in an epidemic where thousands of animals were afflicted.
People eating contaminated beef eventually developed variant Creutz-feldt-Jakob disease and about 200 died.
In Canada, BSE has been a reportable disease since 1990 and the first case was found in 1993 in an imported Salers cow.
Protein supplement contaminated with meat and bone meal was eventually cited as the probable cause, and Canada implemented a ban in 1997 on ruminant feed containing protein from ruminant mammals, poultry litter and restaurant waste.
Following the home grown case of BSE, Canada also brought in strict rules dictating post-slaughter removal and disposal of brains, spinal cords, glands, nerve tissue and parts of the intestine from animals older than 30 months. These are not permitted in feed, pet food, fertilizer or food supplies.
Thanks to this and similar bans in many countries, only 29 cases of BSE were reported in the world last year.
Evans said the control measures have been effective. He and Keough agree some may not have been found.
“To say that we found every single case that was out there would be very difficult to prove or disprove,” Evans said.
Ongoing surveillance remains the key to Canada’s plan to eliminate BSE.
The goal is 30,000 tests per year, but last year only 24,000 were tested. Czub said numbers declined when producers were no longer paid for submitting samples.
“The program is really scrambling and it is very important to keep these numbers up for our country classification for the OIE and our trading partners,” she said.
About 10,000 tests have been done this year.
In the early years of the crisis, some demanded universal testing of every animal slaughtered. However, most animals are slaughtered before they reach 24 months of age and are not at risk. Evans said testing them would be more of a public relations exercise.