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Tuesday, January 6, 2004

The Cow Jumps Over


Dr. Lester CN Simon

In a previous article, we looked at the basic science of a group of degenerative, spongiform brain diseases in which the brain in reduced to a sponge. In this article, we look at the full spectrum of these diseases with emphasis on the more important ones.

There are at least 6 transmissible spongiform brain diseases that affect animals. For over 200 years, shepherds have recognized a spongiform brain disease called scrapie, in sheep and goats. It is called scrapie because the animals degenerate and itch to the extent that they rub against any object and scrape off their wool.

Chronic wasting disease of mule deer and Rocky Mountain elk is a spongiform disease seen in Colorado and Wyoming, USA. Scrapie and chronic wasting disease are the only 2 spongiform brain diseases that appear to be spread directly from animal to animal.

A third disease, transmissible mink encephalopathy, was discovered in Wisconsin, USA in 1947. Encephalopathy simply means brain disease. Ingestion of contaminated food stuffs is thought to be the mode of infection.

The remaining three spongiform brain diseases in animals include exotic ungulate encephalopathy, identified in British zoos in the mid-1980s. Ungulates are hoofed mammals including antelopes, cheetahs and others. Feline spongiform encephalopathy in domestic cats was discovered in 1990. These two spongiform diseases in ungulates and cats are thought to be due to the same infectious agent that causes Mad Cow Disease, the sixth and most notorious of animal spongiform brain diseases.

Mad Cow Disease or Bovine Spongiform Encephalopathy (BSE) was first discovered in Britain in November 1986. The cows’ mental state ranged from initial apprehension to frank madness. Since the 1940s, cattle feed was enriched with meat and bone meal from other animals including sheep and other cows. Ordinary grass was insufficient for cattle.

Offal refers to the entrails and internal organs of an animal that are used as food. The enriched meal for cattle includes offal from slaughterhouses. It goes through a process called rendering. Here, the melted fat is removed as tallow. Tallow is the hard fatty substance from animals. It can be used to make some candles and soap.

After the tallow is removed, the solids comprise meat and bone meal for cattle. How did the first cows with Mad Cow Disease get infected? They got infected from the enriched meal during the winter of 1981-1982. The rendering process had been altered. The use of chemicals called organic solvents and the high temperatures used in the rendering process were stopped. The lack of these chemicals and the absence of high temperatures meant that any infectious agents in the animals used in rendering, survived and were inadvertently passed on. The infectious agents came from scrapie-infected sheep.

The next time you hear someone say they do not eat meat, just smile. Some rendering processes use spoiled meats scraps and animal carcasses. In addition to preparing meat and bone meal to enrich cattle feed, many by-products are derived from the rendering process. Some of these rendered products include high-protein base used in soaps, medicine and candy. Render unto cattle and render unto Caesar.

According to the Wall Street Journal, processed cow fats are used to make cookies and salty snacks taste rich, and lipstick to glide on smoothly. Cow proteins end up in shampoo. Gelatin from cattle hide and bones is found in ice cream, candy, marshmallows and in capsules encasing drugs. Cow lips are used in taco filling and other offal parts are found in pet food.

The manufactures claim that none of the organs that are known to transmit Mad Cow Disease are used in their preparation. If we accept this as truth, we have to also accept that the science of Mad Cow Disease is evolving. The brain and the spinal cord are known to be the areas that harbour the infectious agents called prions.

Dr. Prusiner, the discoverer of prions, noted that there are discoveries that widen the spectrum of prion diseases in mice. These discoveries are prompting a search for human prion diseases that affect the peripheral nervous system and muscles.

The spongiform brain diseases in humans include Kuru, Creutzfeldt-Jakob Disease (CJD), Gerstmann-Straussler-Scheinker Disease and Fatal Insomnia.

CJD is the most common human spongiform disease. Yet it is very rare. The estimated incidence is about 1 case per million, per year, worldwide. Before 1995, it existed in 3 forms. Sporadic or random CJD (about 85%), familial CJD, and CJD from use of infected medical organs or products. Familial CJD means that bad genes are passed on to an offspring.

Sporadic CJD is rare in people under 30 years of age. There is progressive mental deterioration and death occurs in less than a year. In late 1995, a new form of CJD was observed in Britain. It was called new variant CJD. In retrospect, the first case was probably in 1994, some eight years after Mad Cow Disease was discovered. It was called new variant CJD because the patients were teenagers or younger than classic, random or spontaneous CJD patients. New variant CJD (nvCJD) patients survived longer.

Kuru is due to cannibalism among the Fore people of New Guinea. Industrial cannibalism in scrapie-enriched cattle feed is the cause of Mad Cow Disease and nvCJD is due to humans eating infected beef products.

Canine, ovine, bovine, asinine? Respectively: tooth, sheep, cow, stupid or foolish?

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