World Bank (Wilson); Harvard School of Public Health (Halperin)

Published as a "Comment" about HIV prevention in The Lancet (Vol. 372, pp. 423–26), a series publication presented at the Mexico City, Mexico, August 2008 International AIDS Conference, this article expands upon the "rallying cry" Know your epidemic, know your response, stating that the era of standard global prevention is over. The authors discuss the state of global HIV and AIDS as not a single epidemic, but a multitude of diverse epidemics. They distinguish between "concentrated and generalised epidemics, which are fundamentally different - not because of arbitrary prevalence thresholds, but about who gets infected and how." Concentration is described as transmission among defined vulnerable groups, such as sex workers or injecting drug users. Transmission among the general population that would persist, resulting from sustained sexual behaviours, despite effective programmes with vulnerable groups, is considered a generalised epidemic. The authors state that Latin America, the Middle East, Europe, and Asia have concentrated epidemics, while Southern and Eastern Africa have generalised epidemics; and the differentiation is less clear in the Caribbean, Central and West Africa, and parts of the Pacific.

Though the authors list a number of pitfalls of determining the status (concentrated or generalised) of an epidemic, the one most associated with communication is the call to ground participatory consultation in evidence. They point to statistical evidence that HIV is more prevalent in the wealthier, not the lower-income African countries, and among the more educated, upper-income Africans. They also point to evidence that shows a higher prevalence where there is more gender equality. Thus, they state that "[p]articipatory approaches that emphasise putative, largely unproven underlying structural or other social, economic, or political factors (although vital for other non-HIV reasons) can deflect emphasis from the major immediate cause of HIV infection: multiple sexual (and injecting) partnerships."

Once the nature of an HIV epidemic is known, answers to the question of a response contain a mixture of communication-related methods. The authors recognise that the containment of epidemics in South and Southeast Asia, epidemics fuelled by sex work, has been aided by targeted interventions that promote education, condoms, sexual health, solidarity, empowerment, and rights for sex workers. However, other communication-based methods are categorised by the authors as unproven or disproved for reducing HIV incidence. These include: testing and counselling; condom promotion; and school and youth (including abstinence) programmes.

Since, as stated here, partner reduction is found to reduce transmission in generalised epidemics, the authors find that "we know too little about how to effectively promote partner reduction. But this is no excuse not to immediately increase our commitment to well-evaluated programmes aimed at reducing multiple and concurrent sexual partnerships. Lessons learned from the successes in reducing population-level HIV prevalence in countries such as Uganda may prove useful for prevention programming. It seems that the Ugandan response stimulated personalisation of risk in a way that fostered community mobilisation for behaviour change, without increasing stigma. Second, the intensive use of a coordinated multilevel approach, involving clear and consistent risk-avoidance messaging at all levels, assisted in changing societal norms of behaviour. And third, it seems that focusing such efforts for risk avoidance and partner reduction on adult men was key to reducing the sexual networks that fuel HIV transmission in high prevalence countries."

In areas where the type of HIV epidemic is not yet clearly defined, it is also unclear whether to promote making sex work safer among populations where HIV and AIDS is concentrated, or to convince countries to invest in the normative and social changes required for partner reduction, responding to generalised epidemic conditions. Where an intensive focus on partner reduction (Uganda) was shifted to other approaches, including social marketing of condoms and abstinence, HIV incidence may now be increasing again, as are multiple partnerships, indicating a need to examine results of programme approaches. Emerging evidence also indicates that antiretroviral treatment - while treating the condition of millions of people - might make behaviour change even more challenging, as AIDS is increasingly perceived as a chronic manageable disease.

In summary, the article concludes that "knowing your epidemic" must be an uncomplicated analysis resulting in decisive action. Preventative methods used among sex workers can be effective, while finding solutions for men who have sex with men and injecting drug users "requires new and creative strategies and allies." In generalised epidemics, resources need to be diverted from unproven or disproved approaches and applied to "two proven but admittedly sensitive approaches already at hand: male circumcision and partner reduction." Finally, where epidemics are both concentrated and generalised, a balance of interventions should be applied according to an analysis of the transmission sources.

Note: this article is freely accessible with a complimentary registration/log-in to the Lancet. Click here for access.

Click here to access "Putting prevention at the forefront of HIV/AIDS", by Richard Horton and Pam Das. This Introductory essay to the Lancet issue, which presents a series of articles on HIV and AIDS, provides background and the rationale for this Lancet effort to provide a simplified roadmap for countries seeking to develop their own evidence-driven strategies to respond to AIDS.

The Lancet website, accessed on September 4 2008.