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How did researchers fail to find what’s driving Africa’s HIV epidemics?


HIV is not an easy virus to catch – it needs memorable skin-piercing events or intimate sexual contact. So it shouldn’t be too hard to find out why people living in city X have 50-100 times greater risk for HIV than people living in city Y. How? Find people with new infections and ask them about recent skin-piercing events (injections, tattoos, accidents) and sex partners. Then go look for the source. See if the people who gave the injections or other skin-piercing procedures reliably use sterile instruments; test others who visited the same clinic. Trace and test sex partners. Then sequence viruses to look for matches and therefore linked infections.

Over the past 30 years, international and foreign organizations have funded a lot of research on HIV in Africa. This research includes 44 randomized controlled trials testing interventions to prevent HIV among adults. How did these studies fail to explain what is different about HIV in Africa? As crazy at it seems – they didn’t ask, didn’t look, and didn’t report what they found. The details of this failure are documented in a review available on this website at: https://dontgetstuck.wordpress.com/downloads/ and from the Social Science Research network at:
http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1940999.

Only 5 of the 44 studies reported recent sexual risks for people with new HIV infections (having any vs. no sex partner, or less than 100% condom use). Only 5 of 44 studies reported recent injections in people with new HIV infections. No study – not one! – traced any HIV infection to any non-primary partner or blood contact. When experts say that non-primary partners account for most HIV in Africa – How do they know? They never looked! Less than 5% of more than 4,000 new infections observed in these 44 studies were traced to spouses that were already enrolled and followed in the studies. Otherwise, no study traced any infection to any other source.

What is the chance that foreign-funded researchers in Africa will overcome decades of incompetence to finally do what they should have done long ago – trace infections to find their source? More likely, African governments and the African public will lead the way.

One response to “How did researchers fail to find what’s driving Africa’s HIV epidemics?

  1. Eva Deuchert October 12, 2011 at 11:16 am

    As economist I strongly agree that with scarce resources, any decision on the allocation of funds should be based on economic principles. I therefore strongly welcome the rethinkHIV initiative to rank competing HIV/AIDS interventions based upon benefit-cost metrics aimed at helping policy-makers and donors prioritize investments.
    One of the key problems with their approach is, however, that we have only very little empirical evidence on the benefits of these interventions. Only a small number of randomized field experiments were conducted. The ones on preventing sexual transmission often use self-reported sexual behavioral change as their key outcome variable but fail to show that these interventions result in a measureable decline in the number of new infections – which should be the prime outcome of the trials from my point of view. Trials on preventing non-sexual transmission exclusively focus on preventing mother-to-child transmission. Any empirical evidence on the effectiveness on preventing iatrogenic HIV transmissions is entirely missing.
    So, on which basis are estimates for benefits made? The authors of the commissioned research papers use mathematical models similar to the ones provided by the UNAIDS “Know Your Epidemic & Modes of Transmission” initiative (http://www.unaidsrstesa.org/thematic-areas/hiv-prevention/know-your-epidemic-modes-transmission). Any estimates derived from these models, however, can be only as good as the underlying model.
    One possibility to check reliability of the benefit estimates is to investigate if these type of models can predict the epidemic situation of many African countries in the long-run. Assuming that HIV is predominantly heterosexually transmitted so that other transmission mode can be ignored (at least for adults), it has been shown that simple models based on differential equations and sequential sexual partnerships (similar to the UNAIDS models) entirely fail to predict an HIV epidemic observed in Africa once they are parameterized with realistic model parameters. In fact these models would often not even predict an outbreak:
    http://www.demographic-research.org/Volumes/Vol16/5/16-5.pdf
    Other models model concurrent partnerships. With these models, at least an outbreak can be predicted. But again, parameterizing them with realistic model parameters dramatically reduces the role of sexual transmission suggesting that concurrency cannot be an important driver of HIV epidemics in sub-Saharan Africa:
    http://www.jiasociety.org/content/14/1/44
    I strongly agree with UNAIDS: Knowing the epidemic and the importance of different transmission modes is an important pre-requisite for identifying gaps in current prevention response and resource allocation. However, I do not believe that using unrealistic mathematical models, ignoring the existing empirical evidence on the importance of non-sexual transmission modes, and downgrading statistical anomalies (such as the high share of HIV-positive children in Africa have HIV-negative mothers or the high prevalence among self-reported virgins) as data-errors will provide any new insights, neither on the importance of different transmission modes, nor on the cost-benefit ratio of different prevention methods.

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