Refusing blood donations from homosexual men is discriminatory, but there are developments which may lead to changes, writes Dr William Murphy.
The Irish Blood Transfusion Service, in common with the majority of transfusion services worldwide, causes serious offence to many people, not all of them homosexuals, by its policy of refusing to accept blood donations from men who have ever, even once, had sex with another male.
The policy is blatantly discriminatory on grounds of gender preference and it diminishes men who have sex with men by preventing them from full participation in the community.
Men who are excluded on these grounds would otherwise make excellent blood donors, while many others refuse to support the BTS in protest against its discriminatory policy.
So what brought this state of affairs into existence and why does it persist? When Aids first began to appear among people who had received blood transfusions, in the early 80s, there was no test for the virus; it was known however that there was an epidemic of Aids among gay men.
As an emergency measure, gay men were barred from donating blood. It worked: by the time a test for the virus appeared, the rate of transmission by blood donation had already fallen precipitously and thousands of lives had been saved.
Transfusion services worldwide followed suit. Other groups with high rates of HIV infectivity were also systematically excluded as were other categories of higher- than-average risk for transmitting other infections.
For example, in Ireland, people who have spent more than 12 months cumulatively in Britain or Northern Ireland between 1980 and 1996 cannot donate because of fears they may be more likely to spread vCJD through transfusions.
These policies cannot of themselves render the blood supply free from infection, but they provide some partial defence, and the supply may be less safe without them. Whether homosexual men are a continuing risk for transfusion-transmissible infections can be addressed in the context of risks from known diseases and risks from new, more or less unknown diseases.
Infections with sexually transmissible diseases are more common in homosexual men than in others. They may not comprise the majority of such infections in the community or the only identifiable category of higher-than- average risk in the community, but they form a recognisable category of higher-than-average risk, insofar as they form a category at all.
So do other groups and, where they can be recognised, transfusion services exclude them too.
However only a small minority of homosexual men are at risk; the notion that all gay men are uniformly at risk is as offensive as a similar statement would be for exclusively heterosexual men.
The transfusion services have good tests for HIV and other infections, so the chances of missing an infectious donor are small. However these chances are real - there is a time lag between a donor being infected with a virus and the tests on the donor's blood becoming positive for that virus.
The time lag varies between one to two weeks for HIV to a month or more for hepatitis C. Any person or group of persons with higher rates of disease increase the chances that new infection will be missed because of this.
Transfusion services argue that homosexual men caused rapid dissemination of a new disease through blood transfusion in the past, therefore could do so again.
This argument does have scientific validity from the point of view of risk- management in complex systems, but it is impossible to measure its value in numerical terms.
However, the latest threat posed by an emerging disease - vCJD - was from a food-borne source and others, such as Sars and malaria, have nothing to do with sexual transmission.
The transfusion services argue that accepting homosexual men as donors will not make transfusion safer, but may make it less safe.
While this may be generally true, it is not universally so; any regular blood donor in a stable partnership is safer than one who is not, all other things being equal.
It is often pointed out that the transfusion services do not exclude promiscuous heterosexuals or even heterosexuals who have had a recent new partner, common associations with new cases of sexually transmitted disease.
In other words the transfusion services are inconsistent, open to the charge of unfair bias against homosexuals and unreasonable in their categorisation of homosexual men as homogeneous, promiscuous and unreliable.
Transfusion services worldwide are scarred by their previous mishandling of emerging diseases, and are, understandably, extremely cautious about moving from one fairly secure position to another, perhaps less secure one.
This is particularly the case in this situation, where the beneficiaries of the proposed change are not patients, but others who are not directly dependent on the transfusion services for their well-being. Nevertheless it would be a far better position for human and societal reasons if the transfusion services were to remove the ban on homosexual men.
There are some prospects for this. Several groups are working on methods to remove possible infectious agents from blood transfusions by chemical treatment. If such a process becomes available, any rationale for excluding homosexual men will have disappeared.
A number of countries limit the ban to a period between six months and five years. The experience of these services may inform the future policies of the others.
In the meantime, it behoves the transfusion services to acknowledge and attempt to limit the offence caused, to try to attenuate the collateral damage and to do their best to move forward cautiously and safely as developments in technology and emerging experiences allow.
Dr William Murphy is national medical director of the Irish Blood Transfusion Service