HIV/Aids was not one epidemic but four: first the virus, then disease, next death, and finally societal decomposition, each superimposed upon its predecessors. The timing of each epidemic varied with distance from the western equatorial epicentre and from the initial focus of infection in each region, but the sequence was the same everywhere. The process highlighted two distinctive features of heterosexual HIV/Aids as an epidemic disease. One was its slow incubation, which meant that individual deaths were spread across many years rather than concentrated in a brief period of mass mortality. During the influenza epidemic of 1918 in the South African town of Kimberley, so a missionary recalled, ‘No coffins could be provided, as there was no one to make them; the dead were wrapped in blankets and piled one upon the others and taken in carts to the cemetery. Thirty at a time I have buried in a long grave, and we buried many three deep.’ During the Aids epidemic burials were equally common but for the most part individualised, with much of the ceremony that Africans had long devoted to them. This compounded another consequence of the virus's slow incubation: HIV/Aids was an impoverishing disease, disabling advanced cases from working while imposing heavy costs for months of medical care and the eventual funeral.

Here the second distinctive feature of the African epidemic was crucial. Heterosexual Aids was a family disease whose impact fell first and most heavily upon the household, with young adults as the chief victims. The result was a proliferation of orphaned children and elderly grandparents caring for them. The vulnerability of these new, misshapen households became clear during the famine that struck much of southern Africa in 2002, a ‘new variant famine’ that might herald a phase of societal decomposition. Yet here, too, the slow action of the virus shaped the epidemic, for by 2005 there was no evidence of the social disorder that had sometimes accompanied more explosive epidemics in the past. Nor was there necessarily reason to expect it.

Recognition that deaths were occurring on an unprecedented scale spread slowly behind the virus, between five and ten years after the epidemic struck each locality.