Mad cow disease and blood donation?

Question

Hi, I have read that people who lived in the uk from like the 1980s to 1996 cannot give blood for fear that their blood may be contaminated with mad cow disease. Plus, the blood bank can't test the blood for it as no test exists. However, I didn't was a vegatarian when I lived in the UK. Also, if the person had the mad cow disease, wouldn't they have died anyway (and dead people can't donate blood)? So what's the point of this rule?

Answer 1

The group of people you are talking about are allowed to give blood in the UK, but not in some other countries such as the US. In the UK we figure that people here have already been exposed to plenty of prions (the infectious agent that causes mad cow disease) during the 80s and 90s, so it's not that much of an extra risk for them to get a blood transfusion from another British person. But people in countries that didn't have much BSE, such as the USA, have not been exposed to the disease in the same way that British people have. Therefore if they have a blood transfusion from a British person, there is a miniscule but real risk that they could be exposed to prions for the first time. Places like the USA are not prepared to take that risk.

As far as I'm aware, 3 people in the UK have caught mad cow disease (it's called vCJD in humans) from having blood transfusions from an infected person. The important thing is that the person who donated the blood was fine at the time they gave the blood - the blood and other tissues are infectious before the person gets ill. Diseases caused by prions can have very long incubation periods, i.e. it may be decades before someone shows any signs. And I think vCJD has occured in a vegetarian girl - prions are very infectious and you would only need sloppy food production in a factory somewhere to contaminate other foods.

It's a very strict rule, but it's not a huge inconvenience for somewhere the size of the USA to exclude this group of people, so they have chosen to be extra cautious.  

Answer 2

Bovine Spongiform Encephalitis (BSE) is attributed to substances called prions. Researchers are uncertain that they can detect prions in the blood, and since it may take many years for BSE or Creutzfeld Jacob disease, it's safer to exclude such persons from the donor pool.