This “starlike” lineage — multiple viruses recently descended from a single virus — is the signature of an explosive epidemic. It sent a chilling message out of the past: In 1960, more than two decades before the first case of AIDS was reported, HIV was already spreading rapidly through Congo’s population.
“It probably passed over into humans a number of times,” Worobey said. “But something allowed the virus to establish itself this time.”
The timing of when that happened plays a crucial part in two new books.
In “Tinderbox: How the West Sparked the AIDS Epidemic and How the World Can Finally Overcome It,” authors Craig Timberg and Daniel Halperin argue that newly developed trade routes carried HIV out of a jungle fastness in southeastern Cameroon and that prostitution then helped it take hold in Congo’s colonial cities. In “The Origin of AIDS,” French Canadian physician Jacques Pepin cites those facts but also argues that unsterilized needles used in mass treatment campaigns against sleeping sickness, leprosy, syphilis and malaria helped spread the virus widely in the decade or two after SIV entered people.
“If the conclusion had been that the common ancestor of HIV dated back to 1850 or 1800, it would have been difficult to explain,” Pepin said. “But the timing laid out in [Worobey’s] studies fitted perfectly” with the historical events highlighted in the two books.
It may be that a much finer dating of HIV’s emergence will be possible. That’s because it turns out that tissue specimens from about 10,000 Congolese patients that go back to the 1930s still exist, held in Congo, Belgium and Arizona.
The material comes from hospitals in three Congolese cities: Kinshasa, Kisingani (formerly Stanleyville) and Lubumbashi (Elisabethville). The Kinshasa hospital also got biopsy samples from a tuberculosis sanitorium, whose patients 60 years ago were especially likely to have had HIV (as are people with tuberculosis today).
In this yellowing, dessicated, wax-embedded trove there may be hundreds of cases of AIDS waiting to be diagnosed. Given how much can be inferred through genome analysis, the samples might one day tell even more about the AIDS pandemic’s secret childhood.
Next week: Who controls the rare resources of human tissue and sets the rules for their use?