Michael Adler and colleagues on HIV today

It has been 25 years since HIV, the virus that causes AIDS, was isolated. Since that time, 25 million people have died of HIV related illnesses. In 2007 there were an estimated 33 million people (CI 30-36) living with the virus and three quarters of all related deaths and two thirds of incident cases were in sub-Saharan Africa.

Globally, for every two new people who start on treatment, five new people become infected, the majority in the developing world.

What these figures reflect is not one homogeneous global HIV epidemic, but rather multiple epidemics driven by different sexual, behavioural and social normative patterns.

The concentrated epidemics (prevalence in specific high-risk sub-populations of more than 5% but less than 1% in the general population) of Western Europe, USA, Asia, Eastern Europe, Latin America and some countries in West Africa are all largely driven by sex work, sex between men, and needle sharing, whereas in the generalised and hyper-endemic countries (prevalence of greater than 1% and 15% respectively), they are largely driven by heterosexual sex.

In the history of epidemics, none have had the global attention or focus that HIV has received, exemplified for example by the establishment of a unique UN co-ordinating agency (UNAIDS 1996), the Global Fund for AIDS, Tuberculosis and Malaria (2001), and the President’s Emergency Plan for AIDS Relief ( 2004).

So far, the most successful responses have been in the area of biomedical interventions – identifying the virus, a successful means of testing for it, measuring viral load, AZT, prevention of mother-to-child transmission treatment, combination anti-retroviral therapy (ART), and ART scale-up.

Across the globe we continue to see that communities can and do mobilise to respond to the epidemic and that strong advocacy can galvanise political interest and increase funding. For prevention, however, the 2.5 million new infections in 2007 are outpacing our response. In concentrated epidemics we know what works – consistent and correct condom use, needle exchange and harm reduction, and reducing stigma and discrimination towards marginalised populations. What we need to do is further scale up these interventions . In generalised epidemics, our main challenge has been the failure to find the right combination of prevention interventions, and the limited success in achieving sustained behaviour change or even agreeing on the right behaviours that need to change . Without an effective microbicide or vaccine, getting our prevention approach right is vital.

An increasingly global challenge is the impact of HIV on women and girls, who carry 50% of all global HIV infections and 59% in sub-Saharan Africa. This reality is fuelled by gross inequities in access to education, unequal power dynamics and gender-based violence and therefore addressing these societal norms and structural barriers must remain pivotal to our response, not only for women, but also for other vulnerable and marginalised populations such as sex workers and men who have sex with men.

There is no panacea and UNAIDS suggests 8 approaches to reverse the epidemic by 2015 . The second of these is Making the Money Work; with the global economic downturn HIV funding, like other development aid, is potentially threatened. At this point in the history of the response we must increase our focus and not lose the momentum made over the past few years and risk a reversal of successes gained.

To mark world AIDS day the International HIV/ AIDS Alliance, an international non-government organisation which supports community action on HIV, poses the question, “How do you think we can achieve a world in which people do not die from HIV-related illnesses.” Post your comments at www.aidsalliance.org/WAD08

Michael Adler is Emeritus Professor of Genito-Urinary Medecine. Centre for Sexual Health and HIV Research, University College London Medical School.

Dr Ade Fakoya is Senior Adviser: HIV and Health Services, International HIV/AIDS Alliance

John Howson is Associate Director: HIV Best Practice, International HIV/AIDS Alliance. jhowson@aidsalliance.org

See also on bmj.com:

AIDS and the irrational

The invisible epidemic