You and Your Cat and Mad Cow Disease

It is now believed that a newly discovered, mutant protein (called a prion) present in nerve tissue is responsible for all the transmissible spongiform diseases (TSEs) and that it is contracted through eating contaminated food (43). Human cases have been strongly linked to the BSE agent (70, 72). This was confirmed with the development of a new test that provided molecule markers to distinguish the TSE from different sources. It was able to show that the new variant CJD occurring in people who ate BSE-contaminated beef was like BSE, and not like the common form of CJD (53, 54, 73, 74).

The hypothesis is that proteins, called prions, present in nerve tissue can be turned into lethal prions that become deformed and convert other prions in an unstoppable process that gradually riddles the brain with holes like a sponge until it results in death (53). The destruction of neurons, the main cells responsible for carrying nerve impulses throughout the body is what leads to the symptoms observed with the TSEe, as described earlier. The prion cannot be destroyed.

It has been proposed that every mammalian species normally has the disease at a rate of about one in a million, and every species should have its own, but rare, form of TSE. (53) However, if that one diseased animal ends up as feed, the infectious agent can be passed to the animals consuming that feed. Then when those contaminated animals are fed to others, the disease can spread rapidly among the susceptible species. The fact that TSEs can be spread between species increases the odds of infected animals entering the system. The ‘species barrier,’ which usually protects one species from another’s diseases, is more like a sieve with the TSE prions. USDA’s Linda Detwiler said that testing for that one in a million cow would be too expensive. “You just have to do all the preventions. You can’t stop the one-in-a-million from occurring” (76).

How much of the prion does it take to cause the disease? British scientists have determined that a cow can get BSE by eating one gram of infected material - a speck the size of a peppercorn - from another cow. Even a minute trace of the material in meat and bone meal (MBM), the protein supplement produced from rendered animal remains, can infect a cow. (2) According to the European Union's Standing Scientific Committee, "the minimal infective dose considered to be valid for animals should also be applied for humans." The minimum dose is unknown, but British scientists discovered that a piece of wire that had been in contact with the pathogen for five minutes became as infectious as a solution made from infected brain. (2)

Continue to the Next Section --> What Makes the Prion Lethal?

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