Wednesday, November 26, 2008

Can treatment-as-prevention end the pandemic?

AIDS activists around the world cautiously praised the findings of an important new study published today in the medical journal The Lancet. The study, by a group of scientists from the HIV/AIDS and STOP TB departments at the World Health Organization (WHO), uses mathematical models to test the effectiveness of a strategy that includes universal annual HIV testing and immediate treatment for those who are found to be HIV positive. The authors hypothesize that this strategy, if fully implemented, could reduce HIV rates in Southern Africa to 1 in 1000 by 2016 and to 1% prevalence in fifty years.

IRMA is pleased to see the recognition of treatment as an important element in a full spectrum of prevention options. We would like to point one one element from the study summary which is an annoyingly recurring phrase in global HIV policy and studies. The summary states: "We used data from South Africa as the test case for a generalised epidemic, and assumed that all HIV transmission was heterosexual."

To quote from our very own excellent report (if we do say so ourselves), Less Silence, More Science: Advocacy to Make Rectal Microbicides a Reality:
"By focusing almost exclusively on gay men, MSM, and the West when developing policy related to anal intercourse (AI) in the context of HIV prevention programming, we neglect to identify the prevalence of AI between women and men as well as the HIV prevalence among, and indeed, the mere existence of, gay men and other MSM in Asia, Africa and other parts of the developing world. This neglect costs lives. In its ground-breaking report Off the Map, the International Gay and Lesbian Human Rights Commission decried the wall of silence that surrounds AIDS and same-sex practices in Africa. The situation in developing countries outside of Africa is often much the same regarding the collective blind eye turned toward MSM and anal sex practices between women and men.

Precious little research has examined the role of AI in HIV transmission in developing countries. However, studies in Senegal, Ghana, Kenya and Sudan indicate that rates of HIV prevalence among MSM are significantly higher than in the general population. This has also been demonstrated in most countries of Latin America, and in several countries and cities in Asia.

The illegality of AI in many countries and jurisdictions, the strong taboo and homophobia associated with anal sex, and the imprecise language we use to describe populations and behaviours conspire to render these realities invisible. We tend to conflate sex acts with identity through the use of imprecise, misleading language. Phrases like “heterosexual transmission” mask the fact that women and men who identify as heterosexual engage in AI. This lack of clarity, honesty and specificity negates that a significant portion of the pandemic is likely driven by unprotected anal intercourse in regions broadly characterized as being “driven by heterosexual HIV infection.” In this construct, heterosexual HIV transmission automatically translates to vaginal intercourse. While identity, sexual orientation and sexual practices may be related, they are not always so clearly delineated. “HIV infection via unprotected vaginal intercourse” would be a more accurate phrase than “heterosexually acquired HIV infection”.

These are more than innocuous semantics; language matters. Inaccurate language impacts quite concretely on program design and delivery; on research design, particularly for microbicides; on stigma faced by communities, including gay men and other MSM; and, on the deceptive absence of other populations that engage in AI, including heterosexual men and women, lesbians, and bisexuals across the globe.
" (p.13-14)

The Lancet, Early Online Publication, 26 November 2008
doi:10.1016/S0140-6736(08)61697-9Cite or Link Using DOI

Universal voluntary HIV testing with immediate antiretroviral therapy as a strategy for elimination of HIV transmission: a mathematical model
Reuben M Granich MD a , Prof Charles F Gilks DPhil a, Prof Christopher Dye DPhil b, Prof Kevin M De Cock MD a, Brian G Williams PhD b

Roughly 3 million people worldwide were receiving antiretroviral therapy (ART) at the end of 2007, but an estimated 6·7 million were still in need of treatment and a further 2·7 million became infected with HIV in 2007. Prevention efforts might reduce HIV incidence but are unlikely to eliminate this disease. We investigated a theoretical strategy of universal voluntary HIV testing and immediate treatment with ART, and examined the conditions under which the HIV epidemic could be driven towards elimination.
We used mathematical models to explore the effect on the case reproduction number (stochastic model) and long-term dynamics of the HIV epidemic (deterministic transmission model) of testing all people in our test-case community (aged 15 years and older) for HIV every year and starting people on ART immediately after they are diagnosed HIV positive. We used data from South Africa as the test case for a generalised epidemic, and assumed that all HIV transmission was heterosexual.
The studied strategy could greatly accelerate the transition from the present endemic phase, in which most adults living with HIV are not receiving ART, to an elimination phase, in which most are on ART, within 5 years. It could reduce HIV incidence and mortality to less than one case per 1000 people per year by 2016, or within 10 years of full implementation of the strategy, and reduce the prevalence of HIV to less than 1% within 50 years. We estimate that in 2032, the yearly cost of the present strategy and the theoretical strategy would both be US$1·7 billion; however, after this time, the cost of the present strategy would continue to increase whereas that of the theoretical strategy would decrease.
Universal voluntary HIV testing and immediate ART, combined with present prevention approaches, could have a major effect on severe generalised HIV/AIDS epidemics. This approach merits further mathematical modelling, research, and broad consultation.

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