Mad Cow Disease - prions - subceptibility : LUSENET : Countryside : One Thread

This is extracted from a 1996 newspaper article:

The equivalent of mad cow disease in humans is called Creutzfeldt-Jakob (C-J) disease. It usually strikes people in their 50s and 60s, after taking years or even decades to develop. However, for an unknown reason, incidences of the disease suddenly drop about the age of 75, while cases of a more comon dementing disorder, Alzheimer's disease, continues to increase with advancing age.

When an expert British committee identified a cluster of 10 cases of a variant of C-J disease in people younger than 42, some in their teenage years, they concluded they were dealing with a variant of it.

Proven modes of transmission is through injections of human growth hormones (which is why people who have received them cannot donate blood) and tissue, like corneas and the dura which covers the human brain.

Some cases of C-J seem to be clearly hereditary in nature. For example, the disease is 60 times more common than usual among inhabitants of a certain region of Slovakia, and 40 times higher among Libyans who emigrated to Isreal many years ago. There is also a high incidence among Sephardic Jews who immigrated to France from Tunisia and Algeria. These cases, thought to be hereditary, account for up to 10% of all C-J disease. Many hereditary cases can be traced to a mutant gene on chromosome 20. In the hereditary group, each child born to an affected parent has a 50-50 chance of developing the disease. But it is not known whether diet or other environmental factors are important co-factors in producing the disease.

The overwhelming majority of C-J cases occur sporadically and with no clue as to how they are transmitted. Even then, the total number of incidences are unknown since symptoms mimic another dementing disorder - Alzheimer's disease - and, unless a complete altopsy was performed, cause of death was likely given as Alzheimer's.

The prevailing belief is that spongiform diseases are caused by rogue proteins known as prions which are thought to be abnormal variants of the prion proteins normally present on the surface of nerve cells. The disease-causing prions are believed to convert their normal counterpart protein into the abnormal form, in a progressive manner. Normal prion protein is produced by a gene which is widely found in nature, but its function is unknown. Prions lack the DNA and RNA which are the hereditary material of other transmissible disease agents.

One known difference between the agents which cause spongiform diseases and conventional infectious agents is their prodigious resistance to heat, untraviolet light, radiation and many chemical disinfectants. Thus, there is no guarantee that food processing techniques like cooking, pasturization, sterilization, irradiation, freezing, drying and pickling will destory the spongiform agent if it is present in foodstuffs.


In other articles scientists are still puzzled why, if BSE infected meat was widely spread among the English population, so few BSE-related cases have appeared, even given a long incubation period. The tentitive conclusion is for some reason, perhaps a genetic defect, these people were susceptible to it. A natural resistance to some diseases seems common place. Take the Black Death or Spanish Flu. Some people worked with those stricken, in an environment to which they were surely exposed multiple times, yet did not develop it.

Different animal species may have their own form of a spongiform disease. In sheep it is scrappies, in cattle it is BSE and some squirrels in at least part of KY has their own variation, which has now been documented to spread to humans through the local custom of eating their brains.

Bottom line is scientists seem to understand only a small portion of the overall puzzle.

-- Ken S. (, August 09, 2000


Sounds like a B-movie plot - you can't kill it, you can't predict who it will affect, and it causes a terrible death. Grant Speilberg the movie rights, and nobody will sleep at night. Especially if they stop for burgers on their way to the movies! Vegetarians Rock!

-- Soni (, August 10, 2000.

I knew I shouldn't have read this before bedtime!I hate bad dreams. God be with you, ~~Tracy~~

ps-Is there really a problem with cattle and MCD in our country? I've read alot about it on Forum;it sounds terrifyingly terrible- Thankfully rare.How rare I wonder.

-- Tracy Jo Neff (, August 10, 2000.


To my knowledge, there has not been a single documented case of mad cow disease in the U.S. or any country from which we import beef. It seems to be under control in Europe. Due to its long incubation period cases of the human variant form of spongiform disease connected to BSE are still showing up in England, and probably will for a decade or more.

-- Ken S. (, August 11, 2000.

Thanks Ken! [Sigh of relief] Blessings,~Tracy~

-- Tracy Jo Neff (, August 11, 2000.

Nova had a good program on this a few years ago. Cases of the (human) disease increased 20% last year in Brittan - but this is probably over a small base.

-- charles (, August 15, 2000.

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