Challenging the concurrency hypothesis

via Journal of the International AIDS Society, by Larry Sawers and Eileen Stillwaggon

A new study from the Journal of the International AIDS Society challenges the notion that concurrent sexual partnerships are especially common in sub-Saharan Africa, and that they are the driving force behind the region’s high HIV prevalence.

The authors find that research seeking to establish a statistical correlation between concurrency and HIV prevalence either finds no correlation or has important limitations. They also suggest that mathematical models of the spread of HIV require unrealistic assumptions and ignore evidence of low concurrency in Africa.

They conclude that individuals promoting the concurrency hypothesis have failed to prove that concurrency is highly prevalent in Africa, and that those relationships lead to more rapid spread of HIV, and call on policy makers to focus on better-established drivers of the epidemic.

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Reducing Numbers of Sex Partners

via AIDS and Behavior

Multiple and overlapping sexual relationships, commonly referred to as sexual concurrency, are believed by some to account for the rapid spread of HIV infection in sub-Saharan Africa. Research shows that concurrent sex partners are prevalent in several populations hit hardest by AIDS including gay communities, commercial sex workers, and some countries of sub-Saharan Africa. Recent research shows sexual concurrency may be playing a role in resurgent HIV infections among gay and bisexual men in North America and emerging HIV epidemics among men who have sex with men in Asia. In addition to epidemiological trends, the potential impact of concurrent sex partners on the spread of HIV transmission is biologically grounded. Sexual concurrency is thought to afford the rapid turnover of HIV when multiple partners are exposed to the virus during the brief and highly infectious period of acute infection. Mathematical models suggest that concurrent sex partners during acute HIV infection may be a driving force in heterosexually transmitted HIV epidemics of southern Africa. Other known and unknown co-factors for HIV transmission also interact with sexual concurrency to propel HIV epidemics. While stimulating great interest, the existing empirical research on the role of sexual concurrency in HIV epidemics is not definitive. In the February 2010 issue of AIDS and Behavior (volume 14, Number 1) Lurie and Rosenthal pointed out that sexual concurrency has not yet been empirically shown to increase HIV transmission beyond what would be expected from multiple sex partnerships that do not overlap in time.

For the full article click here.

Concurrent sexual partnerships and the spread of HIV - ‘the evidence is limited’

by Roger Pebody, via Aidsmap

The theory that multiple, overlapping sexual partnerships are a key driver of generalised HIV epidemics in Africa has been attacked as being based on insubstantial evidence. The critics, writing in the journals AIDS and Behavior and The Lancet, argue that researchers lack a precise definition of concurrency or a standard way to measure it, and that the data do not show a significant association between concurrency and either HIV incidence or prevalence.

However this critique has stimulated a fierce debate in the United States. Proponents of the concurrency thesis argue that the critics’ analysis of the data is selective, that evidence from a wide range of sources supports the thesis, and that it would be irresponsible for prevention programmes in Africa to ignore this issue.

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Hans Rosling on HIV: New facts and stunning data visuals on Ted.com

Hans Rosling unveils new data visuals that untangle the complex risk factors of one of the world's deadliest (and most misunderstood) diseases: HIV. He argues that preventing transmissions -- not drug treatments -- is the key to ending the epidemic.

[Thanks to IRMA Steering Committee Member Roy Wadia for bringing this to our attention]

Excerpt:

But focus now is back on prevention. It is only by stopping the transmission that the world will be able to deal with it. Drugs is too costly -- had we had the vaccine, or when we will get the vaccine, that's something more effective -- but the drugs are very costly for the poor. Not the drug in itself, but the treatment and the care which is needed around it. So, when we look at the pattern, one thing comes out very clearly: you see the blue bubbles and people say HIV is very high in Africa. I would say, HIV is very different in Africa. You'll find the highest HIV rate in the world in African countries, and yet you'll find Senegal, down here, the same rate as United States. And you'll find Madagascar, and you'll find a lot of African countries about as low as the rest of the world. It's this terrible simplification that there's one Africa and things go on in one way in Africa. We have to stop that. It's not respectful, and it's not very clever to think that way.

Watch, listen, read the transcript.