7 - Causation: A Synthesis

Summary

The HIV-1 epidemic that Kapita Bila had first glimpsed in Kinshasa in the mid-1970s had taken almost exactly ten years to spread and become visible among the African peoples at the three corners of the continent, appearing in Ethiopia, South Africa, and Senegal almost simultaneously in the mid-1980s. Having traced that expansion, it is time to return to President Mbeki's question: why has Africa had the world's most terrible HIV/Aids epidemic? An answer must bring together the nature of the virus, the historical sequence of its global expansion, and the circumstances into which it spread, giving particular weight among those circumstances to gender inequalities, sexual behaviour, and impoverishment. Many existing answers perhaps concentrate too exclusively on the circumstances, arguing for the primary importance of either sexual behaviour or poverty.

The distinctive features of HIV as a virus were that it was relatively difficult to transmit, it killed almost all those it infected (unless kept alive by antiretroviral drugs), it killed them slowly after a long incubation period, it remained infectious throughout its course, it showed few symptoms until its later stages, and when symptoms appeared they were often those common to the local disease environment. This unique combination of features gave a unique character to the epidemic, ‘a catastrophe in slow motion’ spreading silently for many years before anyone recognised its existence. One consequence was that whatever part of the world had the first such epidemic would suffer especially severely, for the epidemic would have time to establish itself, unseen, not only in many people over a large area but in the general heterosexual population, where it would be vastly more difficult to contain than in some limited high-risk group contracting the disease through the initial infection of individuals whose distinctive behaviour patterns had brought them into contact with it.

Thus the fundamental reason why Africa had the worst Aids epidemic was because it had the first Aids epidemic. Understandably, many Africans were initially unwilling to accept this, rejecting the notion that HIV evolved from SIV within Africa, despite the powerful evidence for it, because they felt that it was a racial slur - as indeed some commentators intended it to be.