When someone died of immune deficiency, the death may have seemed unremarkable amid all other sources of mortality. Life was hard, life was perilous, life expectancy was short even apart from the new disease, and many of those earliest HIV-positive people may have succumbed to other causes before their immune systems failed. There was no epidemic. But the chain of infection sustained itself. R0 remained greater than 1.0. The virus seems to have traveled just as people traveled in those days: mainly by river. It made its way out of southeastern Cameroon along the headwaters of the Sangha, then
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