Mark Purdey has theories about the origins of BSE and they don’t jibe with many scientists’ views on the subject.
The British organic farmer, trained in zoology, nevertheless has a following among farmers and environmentalists.
Purdey’s cattle became infected with BSE at the height of Great Britain’s outbreak in the 1990s, despite his insistence that they were never fed meat and bone meal.
Since then, he has developed his own theories about what causes the disease.
Purdey has chased the elusive cause of transmissible spongiform encephalopathies across most of the planet and has travelled to almost every location that has had multiple incidents of any TSE.
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After a decade of looking at BSE and other TSEs, he feels the disease is not particularly transmissible or infectious and mostly occurs spontaneously as a result of a combination of forces in the environment.
Purdey was in Saskatoon May 18 as part of a western Canadian tour organized by a small group of prairie cattle producers. Leslie Czar, a cow-calf producer from Hanna, Alta., helped organize the tour.
“As a farmer I’m being blamed by government agencies for an infectious agent. Yet they have no solid proof there is an infectious agent. That is slanderous. If farmers had a lot of money, we’d be in court fighting this,” Czar said.
“Instead we’ve brought Mark Purdey to show us some alternatives. His science is not being (financially) supported and we think it needs to be. This issue needs more research before they blame the cattle industry for it.”
Purdey’s interest began when the British government ordered his cattle treated with organo dithiophosphate insecticides, part of a compulsory warble fly control program.
Organophosphates were used in Britain to treat dairy cattle for warble fly because of the rapid withdrawal times in milk. Purdey fought the order in court but his animals were eventually treated.
Over the years he noticed incidents of BSE in British cattle that seemed to coincide with the use of the warble control pesticide.
Mainstream scientists who studied it at the time ruled out the possibility that the pesticide could cause BSE, but others later said it was possible the organophosphate had made animals more susceptible to the formation of folded prions widely thought to cause the disease.
According to Purdey, BSE can occur if a copper deficiency combines with a series of other environmental factors, including mineral deficiencies, an imbalance or abundance of other minerals that tie up copper in the body and spinal tissue contact with organophosphate pesticides.
He argues that malformed prions in the brain are incorporated by metal piezoelectric crystals that form on nerve tissue that has been damaged by exposure to environmental contaminants.
These “rogue crystals” are charged by low frequency sound waves from passing supersonic aircraft, mining explosions, lightning strikes and tectonic plate activity in the earth’s crust, which in turn create holes in the surrounding brain tissue, called spongiform neuro-degeneration.
Purdey said Britain’s warble fly control policy, compounded by environmental conditions such as the 1986 Chernobyl nuclear reactor explosion and subsequent strontium 90 fallout on Europe and micro-nutrient mineral imbalances, caused BSE in cattle and new variant Creutzfeldt-Jakob disease in humans.
He cites examples of TSEs from around the globe that fit his model, including scrapie in sheep and chronic wasting disease in deer and elk.
Roger Morris, a professor at King’s College in London, England, and one of the world’s leading researchers of prion diseases, said he is more interested in how the malformed prions are spread and infect others.
“We are sure, I am 99.9 percent sure, that this disease is spread through the feeding of infected material,” Morris said during a recent appearance in Saskatoon.
He and most other researchers suspect prions are able to move into the nerve and lymph systems through cells on lymphatic system tissue, called Peyer’s patches, located in the gut. Lymphocytes may then carry the misfolded prion to the brain through the lymph system or potentially the bloodstream, where it finds neurons and infects other, healthy prions.
Scientist Peter Flood of the University of Saskatchewan has studied Purdey’s hypothesis.
“There are strong theoretical reasons to think that mineral status might influence susceptibility to CWD,” Flood said in an August 2003 report on his study of mineral deficiencies.
In the study, which examined the brainstems and livers of 1,250 farmed elk slaughtered in 2001 as part of a CWD investigation, Flood found no significant differences in copper levels between the 53 CWD-infected animals and those that weren’t infected.
“Within affected farms, copper and manganese status does not influence susceptibility to CWD,” Flood said.
“This does not exclude the possibility that mineral nutrition plays some role in the progress of the disease or its spread. Nonetheless, our data suggests that such a role, if it exists, is probably rather small.”
Flood said TSEs are a complex disease and the role of minerals “does not exclude or weaken the current scientific view that the primary cause of the disease is a proteinaceous infectious agent (prion). This is the view on which our current control measures are based.”
Those control measures appear to bear out the theories about prion diseases to which most scientists subscribe.
Chris Clark of the University of Saskatchewan’s Western College of Veterinary Medicine agreed.
“(The) control measures taken through the British feed ban appear to be working as the number of infected animals is falling in direct relation to the feed ban timing,” he said.
“I just wouldn’t want anyone to start focusing on Purdey’s ideas and decide to abandon control measures that are working.”
Morris said cases will appear for years to come, but at low levels.
“If this disease were a result of environmental factors, then we would not see this type of reduction as a result of feed bans. It is no coincidence.
“The copper theory was tested to destruction (in British government labs) without any evidence being found for it. Tectonic shifts, sonic booms? I prefer to look at the (many millions) of prions being formed in the body every hour of every day and think maybe one or two go very, very wrong and defy destruction, infect others and are passed on through some ill-thought-out human (food handling and animal feeding) practices.”
Czar said the debate over Purdey’s theories is healthy for the North American cattle industry.
“It keeps people thinking,” he said.
