HIV exposes deep moral divisions between the people society deems to be "good" and those who are seen as "bad".

If the world's really going to prevent HIV gaining any more ground, a lot of countries will need to have the courage to admit that certain marginalised groups in society do exist, have the same rights as other citizens, and need support when it comes to HIV prevention. We're talking about sex workers, gay men and injecting drug users, who are already marginalised and also especially vulnerable to HIV infection.

Infection rates are growing among these ostracised groups, the World Disasters Report highlighted when it was released last week by the International Federation of Red Cross and Red Crescent societies, arguing that HIV is a disaster.

Any successful HIV prevention work needs to be politicised to deal with the double stigma towards HIV and people pushed to the edges of society.

Internationally, aid for HIV prevention has been politicised, but often in ways which make it less - rather than more - likely that countries will provide HIV prevention services to those in need.

Through the U.S. government's Plan For AIDS Relief (PEPFAR) and its other international development funding, this one country has a huge influence over HIV prevention in poor countries.

In its disastrous push for abstinence-only approaches, the U.S government prevents any organisation that receives American funding from supporting sex workers.

Our research in Uganda and other countries exposes the negative impact that these ideologically based HIV prevention programmes have had on the reputation and supply of condoms.

Given that some governments have been using the power of aid to dictate who gets support for HIV programmes, it seems obvious that this is where multilateral and U.N. agencies should take centre stage.

The United Nations should take the global leadership on HIV and ensure that recommendations and responses to HIV prevention are based on good evidence and respect for the human rights of all people.

Unfortunately, the politics of aid prevents the U.N. from taking this strong leadership role.

The neutrality of the U.N. renders it unable to take the leadership needed on HIV. Despite receiving huge amounts of funds for HIV prevention and having played a key role in raising awareness of HIV as a global issue, the U.N. has been noticeably silent on issues such as sex workers, drug users or men who have sex with men.

Despite the strong evidence showing how needle exchange programmes drastically reduce HIV risk for injecting drug users, donors have balked at funding these "harm reduction" approaches because they are seen to support people doing things that are both illegal and often judged as immoral.

The result of this failure to reach those marginalised groups who are most in need is that HIV prevention reaches less than 9 percent of gay men, 8 percent of injecting drug users and less than 20 percent of sex workers.

This is simply not adequate.

HIV prevention efforts will never succeed if we can not even manage to provide HIV prevention programmes to those groups which are most vulnerable to HIV infection.

HIV prevention is becoming a defining issue of our times. It provides a lens to analyse the world today.

It is a lens through which we can gain new perspectives on, and a new sense of urgency for addressing, the day-to-day problems experienced by marginalised groups in society.

It is a lens that offers new insights on the profound injustices that lay still at the heart of many personal relationships.

It is a lens through which we can see the distorting power dynamics of the international system.

None of these can be addressed in isolation. We need to recognise that successful HIV prevention needs political engagement.

Reuters AlertNet is not responsible for the content of external websites.