I know that, but there is also a period after which it can be determined to not be so. So even after that window of incubation, there is somethig that I remember from the United Blood Services pamphlet - if you're a man who has had sex with a man, period, they won't take your blood.
The numbers back them up. If there is a better set of exclusions than blanket MSM all that needs to be done is demonstrate their effectiveness and most haematologists will back the change.
And exactly what surplus of donated blood do we have?
Enough to exclude upwards of 5% of the donor population on BSE grounds. If you are worried about a blood shortage the BSE exclusions would be the first place to make changes, there is no demonstrated risk to including them and you get many more potential donors for relaxing them. Again there is a three way trade off here: blood safety, risk perception, and availible donors. While it would be nice to increase the latter, it is a hard sell when you decrease the former.
Why does perception even matter?
When you have a child in a car accident who was exsaunginating do you want her doctor to have to dick around with parents afraid of the blood supply (either convincing them of the safety or going through the hoops to override parental consent)? No medical professional I know thinks that is a good thing. Likewise when you have an urgent, but not immediately life threatening condition and you require blood transfusions, do you want to have doctor's forced to wait until they can suck dry a familial donor? There are many ways in which a suspect blood supply hurts people, and not just those who are ignorant. These are sufficiently worrisome that blood banks would rather have overly broad exclusions than have these issues.
The long and the short of it is a suspect blood blank, legitimate suspiscions or not, is bad for public health.
BSE? What is that?
Bovine spongiform encephalopathy, aka mad cow disease.
But take, for example, if two men have been exclusive partners for over a year, and have been clean since day one. If they've only had sex with each other, and have not participated in any actions that may infect them, they're still not allowed to donate blood.
The problem comes in that "exclusive" requires on partner to take the other at his word. There will be a certain percentage of "exclusive" couples which aren't in fact truly "exclusive", those couples where one partner is lying will increase the risk factor. Wether or not that is enough to warrant a blanket exclusion, I don't know, but until there is clinical evidence you stay with the exclusions that have been working.
Sexually active people are more likely to acquire some sexually transmitted disease that can be passed through blood. By all logic, you shouldn't have anyone donate blood but virgins that have never used a needle or gotten something that would affect their blood.
It is a tradeoff. Safe blood, low risk perception, and high numbers of donors. Excluding the MSM population, at most 6 odd % of population in Britain (in reality it will be lower as some of those individuals are excluded on other grounds as well, i.e. they've had an organ transplant as well as the fact that the 6% likely includes non-MSM (bi)homosexuals). The blood bank can afford to exclude 6% of the population, it cannot afford to exclude 80-90% of the population.
What about the other 40%? Second, I've been tested since then (the last time was over a year since my last sexual partner) and came up clean.
You aren't getting the numbers right. According the literature including people like yourself results in a 60% increase in risk - in other words if right now 1.2 persons per annum are infected by blood transfusion, then 1.9 will be expected to be infected by including persons like yourself (MSM, but no intercourse within the last 12 months). Removing the entire MSM exclusion results in a 500% increase in risk.
This is a quality control game, and the blood supply wants to be in excess of 99.9999% safe.
And what about just lying about their sexual partners because of the fact they know they're clean?
Nobody knows if they are clean, depending on the test and risks you take you might be 99% sure you are clean but it is impossible to be certain. The only person I'm going to trust make decisions about who is "clean" is going to have a doctorate in haematology.
Yes there are those who know they are a much smaller risk to the blood supply than most of the people they get categorized with. The problem is if it is okay for one person to say, but I'm not as risky as everyone else, how do we keep those who really are risky from making a wrong self-diagnosis. The exclusions are made they way they are because we DON'T want people having to make complicated risk analysis and while you may trust your partner, the rest of don't know him and would rather not rely on his honesty.
How does it increase risk if they haven't had sex? That makes absolutely no sense, whatsoever!
There are different ways of testing the blood, when you use a more sensitive (but extremely cost/time prohibitive) test you can get a lower limit at the number of false positives you will get with the standard test. When using this more sensistive test in clinical studies it was found that MSM - no intercourse in 12 months carried a 60% higher risk. That could be due to extremely long term incubation, compromised antibody function, lying about sexual history, or something else completely. Frankly what is causing it is irrelevent to the blood supply, what matters is that the risk exists and must be dealt with.
Most countries use ELISA to test the blood, it is quick, cheap, and easy. It also requires at least two weeks and possibly 6 months for seroconversion to set in. PCR measures viral load itself, not antibodies, and can detect HIV (and most any other viral disease) when other tests fail. The blood banks cannot afford to PCR every sample that comes through, but you can do clinical trials with it. From those we know that MSM- no intercourse for 12 months carries a 60% higher risk.
What about listing number of sexual partners? I mean, hell, what about the sexually promiscuous heterosexual people out there? They're at a great risk for transmitting diseases, too.
The literature is in extremely good agreement that people lie about that number more than any other sex statistic (think about it how can the average number of male partners dwarf that of females?). Given that in long term relationships it is the total number of partners both have had that matters, it becomes extremely problematic. There should be an exclusion, but it is doubtful that it will be terribly effective.
I say again that by all logic, it may as well only be virgins allowed to donate blood.
It is a tradeoff. Eventually you hit a law of diminishing returns. Right now the experts deem the trade off of a MSM - no intercourse in the last 12 months to not be a good one in terms of risk increased vs donor pool increased.
Second, if clean blood is clean blood, then why does anything else matter to begin with? You'va also yet to answer this question!
We don't know what is clean blood. Even when you use PCR or bDNA you still have a number of false negatives. When can dramaticly increase the cleanliness of the blood, but we can't make it entirely clean. Due to the fact that we can't spot clean blood, we exclude those most likely not to have it. It comes down to probability and if there is a .0001% chance of bloodborn infection, they will exclude even several percent of the population.
Very funny, Scotty. Now beam down my clothes.
