Wednesday, March 23, 2005

Mad Cow, Continued

Hi Lenny. My freebie 500-word limit HaloScan Comment Box left me in the lurch. I started responding to you there but kept getting truncated. Truncation scatters a good thought train, so...

Here was your comment:
Your article begs the questions where do prions come from? Are they common in living creatures and is the danger of prions a numbers thing like bacteria? Would the cessation of feeding cows other cows eliminate the risk of prions? Why are cows feed cows? Is it just cheaper? Inquiring minds, not yet full of holes, want to know.
Here is what I discovered about prions prior to my post:

A prion is a protein. Proteins are made of sequences of amino acids, in this case about 250. Most mammals make a non-infectious protein with these same 250 amino acids. But some mammals introduced a mutation to this protein which made it fold abnormally, giving it its disease-causing ability, and its ability to infect.

Prions from cows most easily infect proteins in other cows, sheep prions most easily infect other sheep, etc. Cross infection (cow to man) was unusual but did happen. We're seeing the likes of cross infection with bird flu in Asia. Halting feeding of cow meat to cows would virtually eliminate infection to cows, and in turn to man. I suspect it would not eliminate prions entirely, since they are thought to originate from a mutation.

A book, Mad Cow USA, the Nightmare Begins by Rampton and Stauber, 1997, apparently made public the gruesome practice of recycling slaughterhouse waste for use as protein/fat supplements to livestock. So, you're right. It's about making money from waste material.

In 1997 the USDA banned use of "most mammal protein" from cattle feed. The ban is not adequately enforced though. Also, it does not ban all mammal protein, which leads to practices such as:
"In North America calves are literally weaned on milk formula containing "raw spray dried cattle blood plasma," even though scientists have known for many years that blood can transmit mad cow type diseases."
- Stauber, 2003
I recall reading that a small amount can infect. It doesn't seem to resemble infection by a bacteria assault where our immune system can tackle a few but get overwhelmed with many.

Here's a good site for keeping up with Mad Cow news:
Organic Consumers Association

I'm glad for inquiring minds such as yours. It lets me do something I love ... elaborate.

1 comment:

adult social network said...

Prions are certainly more frightening than most bacteria or viruses. My question is, an initial prion must have formed by a process other than it's natural replication cycle, so, what is the mechanism for initial prion formation?