Eating Prions and Mad Cows

[science_spot]

Mad Cow Disease has a "real" name.  It's Bovine Spongiform Encephalopathy (BSE). 

This is one disease that falls under the header of Transmissible Spongiform Encephalopathy (TSE).  Other common TSE diseases are Chronic Wasting Disease (deer and elk), scrapie (sheep), as well as Creutzfeldt-Jakob Disease and Kuru in humans.

These diseases are thought to be caused solely by mis-folded proteins, called prions (however, there are other hypotheses).  The prions can be either inherited (DNA variations/mutations) or transmitted among animals.  BSE causes deterioration in the animal's physical and mental abilities, which will lead to death.  One mark of the disease is the inability of the affected animal to stand. 

What difference does it make?  First, cattle is a major component of our food supply, and second, TSE disease occurs in humans, and BSE can be transmitted to humans (varient-Creutzfeldt-Jakob Disease or vCJD).

In the 1980s a BSE epidemic in the UK lead to the purposeful destruction of hundreds of thousands of animals, in an attempt to stop the spread of the disease.  But infected meat had already made its way to the table, thus transmitting the prions (which causes vCJD disease in humans) to people in Britian.  By 2009, over 100 people had died and more are expected due to the relatively long incubation time between infetion and death.  It is known prions are not destroyed by the normal cooking process.

It was determined the transmission of the prions among cattle was likely due to the practice of feeding cattle with ground meal manufactured from "parts" leftover from the slaughter of animals for human consumption, as well as sick animals (cattle, sheep, chickens) not fit for human consumption.  An infected animal was used in the meal that was subsequntly used to feed thousands of animals destined for the food supply.

How do we prevent this from happening again?  The problem has been addressed from a few angles, thus minimizing the risk. 

First, bovine products are not imported from countries/regions with known cases of BSE, including the UK. 

Second, the USA has strict regulations regarding cattle feeds.  Some groups think the regulations regarding the feeds of other animals should be stricter because these animals (chickens, sheep, etc.) are often feed to cattle.  However, since there have only been a few reported cases of BSE in the USA, it seems additional regulation may not be necessary.  Adding stricter regulations on the food industry drives up food prices; we don't need higher food costs without adding a benefit of lower risk.

Third, research into BSE has been plentiful, specifically in terms of detection methods, transmissibility, and prion load of particular organs.  This research has resulted in the regulations set up by the FDA, USDA, andtracking by the CDC.  Luckily, the three most comonly used cattle "parts are blood, milk and muscle meat, which show no infectivity. 

Fourth, our food supply is not the only area the USA addressed concern. Animal products are often used in the manufacture of cosmetics and medicine/vaccines.  These risks are addressed in the paper now deemed the industry standard - "Notes for Guidance on Minimising the Risk of Transmitting Animal Spongiform Encephalopathy via human and Veternary Medicinal Products".  This is a free publication, and not difficult to read.

Have you read enough to swear off beef or milk?  Do you think the USA is doing enough to protect you from the risk of vCJD?

Politcal cartoon by R.J. Matson

 

 **please note - this is a repost of a post from months ago.  It got no responses, and since I am totally swamped at work, I decided to take a shortcut on the science blog today ;)

Tonya

AKA sunmoonstars

The Science Spot

 

[MythicMMM]

Jul. 15, 2009 at 10:02 AM

I know what goes inside hot dogs... but I still eat them!

[comfycouch]

Jul. 15, 2009 at 12:22 PM

I eat very little red meat, but I realize that any amount if it has BSE is too much.  Can you minimize your risk by buying organic or "free range" beef?

[science_spot]

Jul. 15, 2009 at 12:58 PM

comfycouch - probablly.  Since free range beef eat what nature intended (grass and other plant material), there is no risk of transmission through their feed.  However, it would depend on where those cows originated form.  If they were born on a farm in the USA and feed plant material their whole lives, that would be an ideal situation.  If they were born in another country and imported, or at any time fed high risk animal material, and then later moved to free-range and labeled as such, the risk may not be lower.  In my opinion, it not be a huge decrease in risk since the risk of transmission in the USA is extremely low anyway.

 

(Original Poster)

[aurorabunny]

Jul. 15, 2009 at 5:42 PM

No mad cows or dead bodies on my plate, thank you very much. :)

This was a very interesting one, as always.  Thank you!

[say_tay]

Jul. 15, 2009 at 7:26 PM

FYI.. You can't just eat infected meat and "catch" Creutzfeldt-Jakob Disease  aka.  mad cow.  You have to be genetically predesposed for the disease.  My Aunt died of the disease, and my cousins went through the genetic testing to see if they were at  risk.  It was NOT because she ate infected cows. 

[science_spot]

Jul. 15, 2009 at 8:31 PM

say_tay.... yes, most cases of CJD are sporadic (no known cause) or familial (genetic predisposition), but some cases are acquired directly from eating infected beef:  http://www.cjdfoundation.org/fact.html

This is known as vCJD (v stands for variant).

Britian had an issue with that a few years ago, leading to a ban on bovine products imported from the UK.  http://www.telegraph.co.uk/scienceandtechnology/science/sciencenews/3313904/Britain-faces-CJD-epidemic-from-infected-beef.html

Not much is known about transmission, but you can get it from infected meat, although that is not the main cause.

 

(Original Poster)

[aurorabunny]

Jul. 15, 2009 at 9:59 PM

Science_spot is right, you CAN get it from infected meat.