Sunday, July 17, 2011

Concurrency Regurgitated: Dubious Evidence Found Increasingly Credible by Experts

For unbridled spite and anti-African prejudice, packed up in some academic sounding writing, it would be hard to beat Timothy Mah and James Shelton's 'Concurrency revisited: increasing and compelling epidemiological evidence'. Don't worry, it's not in the least bit compelling.

One of the main claims of the article is that the person engaging in concurrent relationships doesn't face as high a risk as all their partners. And this is supposed to explain why another study showed that, although men were five times more likely to report having concurrent relationships than women, women are far more likely to be HIV positive.

The gist of the pro-concurrency argument is that while multiple partnerships alone, even the sort of multiples estimated by those with similar prejudices to Mah and Shelton, do not explain extraordinarily high rates of transmission found in many epidemics, concurrency does explain them.

Concurrency is roughly defined as "overlapping sexual partnerships in which sexual intercourse with one partner occurs between two acts of intercourse with another partner". But because there is little useful evidence about rates of such behavior, in African countries or anywhere else, researchers usually resort to data which bears little application to that (or any other) definition of the word.

Authors promoting the concept as an explanation of high HIV prevalence claim that it is the only possible explanation. However it is not an explanation at all, even if you insist, as the HIV industry does, that HIV is almost always transmitted through heterosexual sex in African countries. It has never been demonstrated that concurrency levels are high where HIV transmission is high or that high levels of concurrency even result in high rates of transmission.

Mah and Shelton proceed to list various pieces of research that show that HIV is probably frequently transmitted non sexually; they just don't see the research as showing this. Earlier researchers 'presumed' that HIV transmission where only one partner in a relationship is infected occurred through extra-marital sex. They generally didn't check and when they did, they chose not to believe anything that didn't fit their prejudices.

People like Mah and Shelton could do with a bit of instruction in basic logic. If you assume the truth of your conclusion and use that as your premise, you will end up with a fallacy. Some of the researchers are even frank enough to use words like 'presume' and 'probably' in their cited remarks. But Mah and Shelton feign complete confidence in their conclusions, despite the high incidence of words like 'appear', 'suggest', 'likely', 'may', etc, throughout their paper.

A recent paper which shows prominent clusters of HIV prevalence around roads does not, as Mah and Shelton wish to suggest, support the concurrency hypothesis. But it is consistent with the hypothesis that infections cluster around health facilities and routes to and from health facilities. However, even after exposure to the many articles they cite in their bibliography, they still adhere to their half baked ideas, finding them "reasonable and salient".

Given their insistence that HIV is almost always transmitted through heterosexual sex in high prevalence countries (though nowhere else), the authors plump for male circumcision as the reason why HIV transmission rates in West Africa have always been far lower than in East and South African countries. This especially weak version of the highly questionable mass male circumcision drive taking place in East and South Africa is said to be 'plausible', which probably shows more about the minds (and scruples) of the proponents than anything else.

Just when you might have thought those tired old arguments had been put out to grass, along come Mah and Shelton to compound them with some even more clapped out considerations. In my next post I'll cover an article which shows that concurrency is not a significant driver of HIV transmission but that multiple partnerships are. And that old chestnut dates back to the days when even experts agreed that HIV wasn't always sexually transmitted. But that's how AIDS billions get spent.


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