When AIDS became known in the early 1980's, there was huge uncertainty about how HIV, the virus that causes AIDS, was transmitted. A sense of fear characterised the way the public responded to the disease. From the public health policies that were made in response to AIDS, the one that remains the best example of utter panic is the ban on gay men giving blood.

Massachusetts senator John Kerry has revealed that the US Department of Health and Human Services will commission a study on the implications of ending this prohibition - a move that is seen as the first step towards repeal. Recently in the UK, the public health ministry announced an easing of a similar ban, but with a bizarre proviso: the gay donor must not have had sex for 10 years before giving blood.

To be clear, it is perfectly possible to protect the public blood supply through testing. The methods for detecting HIV in blood are sophisticated and a long way from what prevailed in those early, scary days when the world was just learning about the disease. And sexual transmission of HIV occurs only when there is unprotected sex, regardless of the sexual orientation of the partners. But the new UK policy of asking for just celibate gay donors, betrays old, nervous prejudice from policy makers. There remains wariness about the sexual practices of gay men - and a sense that homosexuality is a ready store of contagion.

Back in the early days, AIDS was dubbed the "gay plague," by hysterical media reports. At this time, scientists were still learning about how the virus worked. The US Centre for Disease Control, at one point, sanctioned what was called the 4Hs of AIDS, for high risk categories: homosexuals, heroin addicts, haemophiliacs and Haitians. The very notion of branding an entire nation as a risk group, in the case of Haitians, eventually proved incendiary and was later dropped.

At its bare bones, this idea of "high risk" has always been about morality, politics and some prejudice, as much as about biological determination. Being wary of a group that is disproportionately affected by a new disease, must have seemed very much like common-sense. But continuing to hold on to suspicion, even when medical knowledge later offers more precise answers, suggests wilful embrace of ignorance.

Last year, an attempt to lift the gay blood ban failed in the US. Since that time, the "Don't ask Don't tell" (DADT) policy - a prohibition on gays and lesbians serving openly in the US military- has been repealed. President Obama has certified that this repeal will take effect in September, capping a major civil rights victory for gays and lesbians in the US.

The call for an elaborate study to decide whether to allow gay men to give blood, shows how little human rights has figured in the blood donation debate, to date. The harm from stigmatising gay people, for example, is tossed up against a policy that is supposedly motivated by a desire to protect public health. As the argument goes, keeping the blood ban is a necessary trade- off in managing the epidemic.

Remember when efforts to contain AIDS were likened to "war" and an "emergency" - by people such as former US Secretary of State Colin Powell? Well, one result from that way of thinking, is this continued belief that gay sexual relations carry inherent dangers. The restriction on gay men donating blood was viewed as action in a virtual state of emergency, in order to repel imminent threats from spread of HIV/AIDS.

The war-on-AIDS view is flawed because it stigmatises gay men, as wanton sex fiends, all given to dangerous sexual activities. It also supports the fallacy that the HIV virus may be contained simply by eliminating those who are considered to be the main carriers, from activities of a communal nature. It is this reasoning that leads policy makers to believe that maintaining a discriminatory gay blood ban, serves a useful public health purpose.

Follow Philip Dayle on Twitter: www.twitter.com/phildayle72