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Mad Cow Disease is all over the news and it's driving me nuts. I honestly don't understand what the big deal is. "Mad Cow Disease" or Bovine spongiform encephalopathy is caused by introduction of an "infectious" prion into the CNS of cows (there's also a genetic component that's not yet understood fully). Many different animals have prions throughout the body. They're not too sure what they're for, but it looks like it has something to do with binding and regulation of copper ions. Infectious prions are simply a different conformation of the normal prion protein... same protein, just folded differently. The infectious conformation is extremely stable and cells can't break them down. They tend to polymerize and form a plaque. When normal prions come into contact with the infectious conformation, the normal one is converted to the more stable conformation. (The normal prion is about 43% alpha-helix, with the remaining 57% a random arrangement. There are 4 helices attached by some sections of random/irregular amino acid sequence. The helices are pretty stable, while the random arrangement is less so. The infectious prion (from sheep anyway) is about 43% beta pleated sheet and 30% alpha helix. The B-sheet envelops a pair of helices, and it's folded much tighter. For those of you with little knowledge of biochem read that "infectious prion = real stable.") The cells of the brain are perforated by the plaques of prions that build up, leaving the brain a spongy appearance, hence the name spongiform encephalopathy (literally it mesn sumthin like "sponge brain" sickness)... but this happens slowly over the course of several years and symptoms develop equally slow. The infectious prions are only found in the CNS of an animal with spongiform encephalopathy.
Infectious prions are responsible for Chronic Wasting Disease(CWD) in deer, elk and the like, scrapies in sheep and goats, bovine spongiform encephalopathy or "Mad Cow" Disease, Creuzfeldt-Jakob Disease in humans. Fish, chickens, frogs and turtles also harbor prions, but little research has been done with those. It's more than likely that these infectious prions occur in them too. CWD has become a concern in alot of the US as of late, so it's highly possible that the prions may have crossed from the deer to cattle. Left over sheep parts were used as a cheap protein source in cow food for a long while. Though the practice has since been banned, many of the cows still alive today were exposed to this type of feed in their lifetime. Because the disease takes so long to surface, cows may have contracted the disease years ago and the symptoms may not have become apparent as of yet. It's not possible yet to test for the presence of infectious prions without taking samples of brain tissue, which obviously can't happen without killing the animals first (though they're workin on that. There's several research groups addressing the problem of finding infectious prions in the blood).
I'm not sure if heat will denature the infectious prions. I do know that ozone can be used to destroy prions, while leaving the much larger protein and lipid molecules found in the blood of mammals, including cattle and humans, functionally intact, so the FDA is considering ozonation as a possible method of sterilizing ground beef... but there's more research that needs to be done before that happens I think.
You're not gonna end up with a problem from beef, nor meat that was close to a bone. Unless you have pieces of the CNS in there you're good. You won't need to worry about the viscera, cuz we don't eat that stuff in the US anyway. You may run into problems with deer and elk... but because those are cleaned by hand and not machine, there's very little risk that the meat may be infected. The only way I see any problem with that is if you get a spine shot, or maybe a head shot where the bullet travels down through the meat. That's gonna be pretty rare though. Even so, the chances of gettin the disease even in cases where the meat has been infected is still very low. As a general rule... it doesn't matter what animal you're eating, Never Eat Brains! Brains are not for eating.
In review:
- transmissable infectious prions are bad
- you can find them in many animals, not just cows
- it's highly unlikely you'll be exposed to any form of transmissable spongiform encephalopathy in the US
- the chances of contracting any sort of disease because of such exposure is even less likely
- You should be more scared of E.coli 0157
- Brains are not for eating
- Steaks are yummy... yay beef!
Bio lesson over.
Infectious prions are responsible for Chronic Wasting Disease(CWD) in deer, elk and the like, scrapies in sheep and goats, bovine spongiform encephalopathy or "Mad Cow" Disease, Creuzfeldt-Jakob Disease in humans. Fish, chickens, frogs and turtles also harbor prions, but little research has been done with those. It's more than likely that these infectious prions occur in them too. CWD has become a concern in alot of the US as of late, so it's highly possible that the prions may have crossed from the deer to cattle. Left over sheep parts were used as a cheap protein source in cow food for a long while. Though the practice has since been banned, many of the cows still alive today were exposed to this type of feed in their lifetime. Because the disease takes so long to surface, cows may have contracted the disease years ago and the symptoms may not have become apparent as of yet. It's not possible yet to test for the presence of infectious prions without taking samples of brain tissue, which obviously can't happen without killing the animals first (though they're workin on that. There's several research groups addressing the problem of finding infectious prions in the blood).
I'm not sure if heat will denature the infectious prions. I do know that ozone can be used to destroy prions, while leaving the much larger protein and lipid molecules found in the blood of mammals, including cattle and humans, functionally intact, so the FDA is considering ozonation as a possible method of sterilizing ground beef... but there's more research that needs to be done before that happens I think.
You're not gonna end up with a problem from beef, nor meat that was close to a bone. Unless you have pieces of the CNS in there you're good. You won't need to worry about the viscera, cuz we don't eat that stuff in the US anyway. You may run into problems with deer and elk... but because those are cleaned by hand and not machine, there's very little risk that the meat may be infected. The only way I see any problem with that is if you get a spine shot, or maybe a head shot where the bullet travels down through the meat. That's gonna be pretty rare though. Even so, the chances of gettin the disease even in cases where the meat has been infected is still very low. As a general rule... it doesn't matter what animal you're eating, Never Eat Brains! Brains are not for eating.
In review:
- transmissable infectious prions are bad
- you can find them in many animals, not just cows
- it's highly unlikely you'll be exposed to any form of transmissable spongiform encephalopathy in the US
- the chances of contracting any sort of disease because of such exposure is even less likely
- You should be more scared of E.coli 0157
- Brains are not for eating
- Steaks are yummy... yay beef!
Bio lesson over.
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