|MadSci Network: Medicine|
First of all, hope you don't get to much rain in Scotland... ;)
The prions which are said to be the cause of scrapie, BSE (Bovine Spongiform Encephalopoty) and CJD (different kinds though) are hard to destroy. However, some of the data published in newspapers is not really accurate. Yes even at high temperatures not all prions can be completely destroyed, but 99.99% is still good.
In the UK and most other places in the world, BSE-infected cows will not be used for human consumption. Sometimes, the cows don't show symptoms yet when butchered so you could accidently be infected by BSE. The real question is however, how infectious to humans is BSE. A year ago there were 7 possible cases of CJD (Creuzfeld Jacobs Disease) caused by BSE, now there are not really more cases known, although an increase should have been expected.
There is not much BSE-causing PrP (prion) outside the brain and spinal cord. In meat some may be present, but milk is considered to be safe, although milk from BSE-infected cows will be destroyed too.
In summary, in my opinion there is not much risk in eating meat or drinking milk in Europe and the milk will be more safe then the meat. After all, a direct link between BSE and CJD has not been found.
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