Theories on the Cause of Mad Cow Disease

Townsend Letter for Doctors and Patients, Oct, 2001 by Jule Klotter

Mad cow disease is a form of transmissible spongiform encephalopathy (TSE), a progressive neurodegenerative disorder that is also found in humans (Creutzfeldt-Jakob disease), sheep (scapie), and other animals. Each year, about 250 people die from TSE-related diseases in the US. According to current theory; prions, found in animal or human tissue, are believed to cause TSE. The disease spreads through transplantation or ingestion of infected animal tissue. Britain banned the use of bone meal from cows in animal feed in the late 1980s in an attempt to halt the spread of mad cow. In an October 1999 press briefing, Dr. Stanley Prusiner, director of the Institute of Neurodegenerative Diseases (University of California-San Francisco), said that "in prion disease -- an unknown trigger causes the prions to change their shape from a normal spiral shape into an abnormal 'conformation' that can produce disease by destroying brain cells." Dr. Prusiner is investigating a polyamine compound that has apparently eliminated prions in laboratory tests.

A November 1997 paper in Environmental Health Perspectives by Alan Ebringer et al. points out several problems with the prion hypothesis. The authors state that "...There is no structural evidence for the presence of the particle: there are no electron microscopy pictures of such an agent, there is no immunological evidence of infection, and there are no microbiological methods available to grow such a virus/prion agent." They say that "immunodeficient animals, such as SCID mice, do not develop scrapie following scarification with affected brain tissue." Further, "the prion sequence is actually encoded by the host and is therefore a self-protein and probably not part of an external infectious agent."

Ebringer et al. refer to neurological disorders that developed in humans after Pasteur injected them with antirabies vaccines and in lab animals injected with brain tissue during experiments in the 1920s. Immune response to brain antigens in these injections, not an infectious agent, were believed to be the cause of symptoms that include loss of muscle tone, ataxia, paralysis, and death. The authors hypothesize that ESE may be caused by a similar mechanism. By searching the genebank and SwissProt, they found bowel bacteria whose molecular structure partially matches bovine myelin and the bovine prion sequence. The authors suggest that "[s]ome of these bacteria may have contained antigens cross-reacting with brain tissue and thereby leading to the production of antibacterial antibodies with activity against various components of brain and prion tissues."

A third hypothesis concerning the cause of TSE comes from British organic farmer and researcher Mark Purdey. Purdey links the use of the organophosphate pesticide, specifically phosmet, to TSE. British farmers were instructed to pour phosmet along the spines of their cattle during the early 1980s, in order to combat warble fly infestations. The organophosphate contains high levels of manganese. According to Purdey, prions normally bond with copper and carry the metal to the brain where it destroys free radicals. Prions also bond with manganese, especially when copper is deficient. Purdey says that manganese stops prions from folding properly. He visited sites in Britain, United States, Slovakia, Italy, and Iceland that reported TSE and found high levels of manganese in the environment at all the sites. Unlike the infectious prion model, Purdey's hypothesis "matches with the epidemiological spread of CJD clusters in humans. It also predicts the incidence of BSE-type diseases in animals," according to Ireland' s eloNews reporter Fintan Dunne.

Research by David R. Brown, a Cambridge scientist, supports Purdey's assertion that TSE prions have bonded with manganese. Brown has found that manganese levels are 10 times higher than normal in CJD brains. Other scientists, according to an article by Fintan Dunne, have shown that the warble fly insecticide itself deforms prions, making them more likely to bond with manganese. The chemical-pharmaceutical industry in Britain has tried to discredit the pesticide hypothesis and discourage government funding to investigate it.

"Compound fights prion brain disease" by Ed Susman. http//news.excice.com/news/u/991012./20/health-brain-priono? October 12, 1999.

"Bovine Spongiform Encephalepathy: Is It an Autoimmune Disease Duo to Bacteria Showing Molecular Mimicry with Brain Antigens?" by Alan Ebringer, John Pirt, Clyde Wilson, Phil Cunningham, Carlos Thorpe, and Camille Ettelaie. Environmental Health Perspectives, November 1997

"Could the Scientists Be Wrong on Mad cow Disease?" by Elizabeth Piper. Reuters, February 1,2001

"Cover-up: Insecticide causes Mad Cows & CJD" by Fintan Dunne. www.eionews.addr.com/cjdalert.htm.