OPVs were applied to about a million people in sub-Saharan Africa. If only 1% of these became infected with ancestors to HIV then we are looking at a base infection of not one individual, but about 10,000 individuals. This allows explaining the current prevalence of HIV infection in Africa that is hard to explain by appealing to widespread promiscuity amongst the population. If the single Leopoldville case is to explain the beginning of an epidemic – especially given the very unlikely possibility of transmission of the infection except at the beginning and at the end of the course of the disease – then one has to assume very high levels of promiscuity across the continent, which – as we have been warned by the Chirimuutas – maybe prejudicial interpretation in the face of little or no evidence. On the other hand, if 10,000 had been infected then there is enough of base rate infection to explain the current epidemic.

However, in recent years a second theory has come to light. This was explored by Hooper in The River and admitted as a secondary causal factor along with the initial transmission of the SIV to humans via OPVs, but now has been proposed as a theory in its own right. Preston Marx and Ernest Drucker have suggested that the massive injection health campaigns in the 1950s also could have spread the disease onwards. The 1950s not only saw OPV campaigns in Africa, but huge co-ordinated injection campaigns to eradicate a number of diseases across Africa, largely run by the World Health Organisation. There was a massive demand for syringes after the war, and expensive glass syringes were rapidly replaced with cheap plastic ones. However, Marx and Drucker have evidence that many of these syringes were reused, indeed, “health officials in Egypt had waged a mass-injection campaign to treat an illness called schistosomiasis. One result of the campaign was a massive outbreak of hepatitis C, spread through the reuse of contaminated needles”. More worryingly, the rapid reuse of contaminated syringes has been shown to increase rapidly the pathogenic nature and evolution of viruses – thus regardless of whether the virus was transferred naturally only once or a number of time, or had been introduced via OPVs, the reuse of contaminated needles may have lead to the current scale of the problem with HIV infection in Africa.

These latter theories explain a number of anomalies that are not easily explainable with a disease that is hard to transmit. Firstly, human intervention explanations clarify how what should have been a localised epidemic in some parts of Africa, is in fact a worldwide problem, when one takes into account the number of base infections, which sexual promiscuity cannot account for alone. This also explains that despite the virus favouring women, the infection rate in Zambia, for example, is not 2 women for each man, but in fact 1:1.

Understanding the origins of the HIV virus is a very complex and controversial business. Indeed, the OPV theory above is one of the more controversial of explanations of the origins, and is certainly not, at this stage, orthodox knowledge. However, I do find it very hard to account for incredible disparity and high infection rate in Africa by appealing to sexual behaviour alone. The simultaneous appearance of the HIV-2 virus is also cause for concern, as is the ratio of infectees. It seems too much of co-incidence for two simian retroviruses to enter humans at the same time (without any precedent) without there being human intervention. At this state there is not enough evidence to either prove or disprove any theory of HIV origins. It may never be the case. However, it is very difficult to accept that a lone chimp hunter in central or western sub-Saharan Africa began the pandemic with a chimp bite at the same time that a colleague further north had exactly the same happen to him, thus producing two epidemics of HIV-1 and HIV-2.

There’s a documentary about Hooper’s theory is available here: http://www.documentary-film.net/search/video-listings.php?e=5