Madam, - Blood transfusion involves collecting millions of litres of body fluids every year from apparently healthy people and transferring those fluids in large doses into generally unhealthy people.
This creates a unique ecology for infectious agents of disease, especially for diseases so new and so insidious that they have been spread by blood transfusion before their true nature, their existence, or even the biological possibility for their existence, has become known.
This has happened at least three times, possibly more, in the last 30 years - for HCV, for HIV, and now for vCJD.
Caution in dealing with emerging threats would therefore appear appropriate.
Note that the first known transmission of vCJD by blood transfusion had occurred by 1996 - when the existence of the disease itself was discovered - although its transmissibility by transfusion wasn't apparent for a further seven years.
This was far too late to start thinking about measures to prevent it being transmitted.
Note too that that though the number of cases may well end up at fewer than 500 worldwide (it may not), this has nothing to do with science and inspired policies based on it - it is just luck.
Jim Corbett (June 17th) rightly questions the policies of the Irish Blood Transfusion Service in relation to vCJD.
These policies have contributed significantly to the recent and ongoing shortfall in the availability of blood to hospitals in Ireland.
To date over 150 people worldwide have developed vCJD, the vast majority from eating contaminated British bovine material, generally while living in the UK.
The incubation period is 10 years or more, during which time the disease can be transmitted onwards by blood transfusion to others.
The total number of infected and infectious people in the UK (a great many of whom may never develop the disease) is unknown at present, but may be as high as 1 per 10,000 population, based on anonymised studies of surgically removed tonsils.
Until the situation is clearer, caution is clearly necessary.
In this we are not alone - British residents are widely excluded from donation outside of Britain, and within the country itself plasma from British blood donors is considered unnecessarily dangerous for use in the manufacture of blood products such as clotting factors, or for transfusion to children born after 1996, when BSE more or less disappeared from the food chain there.
In the USA, all those resident for three months or more in the UK or for more than five years in Ireland (the majority of your readers) or in other Northern European countries cannot donate.
The threat of spreading vCJD further through blood transfusion is real enough - it seems to be highly infectious by the intravenous route, in marked contrast to its spread by eating infected foodstuffs.
The steps taken to deal with the threat need to be proportionate.
The considerable strain that this places on the blood supply for hospitals is not a reason to avoid precautionary actions.
That excuse did not stand up to scrutiny as a reason for postponing measures to deal with HCV and HIV.
Instead, a sustained effort by the IBTS to get the message out to the public of the need to donate, a sustained response to that need by the society we live in, and a responsible approach to the use of this precious resource by the hospital community are needed to provide this essential medicine in adequate amounts.
In the same issue, Aidan Donnelly takes us to task for not using the blood removed for therapeutic reasons from people with haemochromatosis for blood transfusion to others.
This is problem we would love to solve, and are supporting the Irish Haemochromatosis Society in their efforts to have all therapy for haemochromatosis provided for no cost.
This makes eminent sense, and would remove any economic imperative on people with haemochromatosis to withhold information from the BTS about previous risk activity, such as recent travel to North America (risk of West Nile Virus), or any area where malaria is transmitted, for example.
These would preclude the BTS from taking their donation.
Almost all people with haemochromatosis want to see their blood go to good use because people need transfusion, and it's a shame to waste it, since they've had to have it collected anyway. We agree with them, and hope to remove the barriers before much longer.
We use a very careful and cautious approach to threats and risks in the blood supply. From time to time we will react aggressively to a threat that in time turns out to be less dangerous than feared.
This is far better than waiting until the damage is done before we are convinced avoidance strategies are required.
Part of the price is an increase in difficulty in ensuring an adequate supply of blood for hospitals - to meet this price we must repeatedly ask that the country roll up its sleeves to help us with the task in hand. - Yours, etc,
WILLIAM MURPHY, MD, FRCPEdin, FRCPath, National Medical Director, Irish Blood Transfusion Service, Dublin 8.