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Sex NetsThe puzzling rise and fall and rise of HIV and AIDS in Africa.

By Jon CohenPosted Tuesday, May 15, 2007, at 3:00 PM ET

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Jon Cohen explains why HIV/AIDS rates are particularly high in the United States among black women. David Dobbs argues that a new idea for funding vaccines won't solve the AIDS problem. Kyu Young-Lee goes to Uganda to investigate the battle against malaria, and Adam Graham-Silverman tracks the fight against AIDS in Mozambique.

Epstein could have skipped most of this well-trodden terrain and drilled more deeply into the book's main thesis. By the end of Invisible Cure, much remains mysterious about how to apply the lessons of Uganda and Kagera. How do you create social movements that encourage partner reduction without condemning all concurrency? And we have no idea whether such efforts will have anywhere near the impact she purports. A mix of behavioral and biological forces drives HIV's spread (including one important factor, a pre-existing herpes simplex virus-2 infection, which oddly receives no mention in the book). Several tools now exist to prevent HIV transmission, and, like drugs that treat the infected, they clearly work best in combination. Epstein acknowledges this and calls for more programs that promote partner reduction and educate people about concurrency. Hallelujah. But it's worth keeping in mind that Uganda, despite its miracle, had an adult-prevalence rate of 6.7 percent in 2005, which is still devastatingly high.

This cloud over Uganda's miracle may relate to serious questions that prominent researchers studying Ugandan sexual behavior have raised about the role that behavior change played in the HIV prevalence drop from 1991 to 2005. To begin with, there is a dearth of reliable data from the early years of the epidemic from which to figure out precisely what led to the decline. In addition, one study found that from 1994 to 2003, prevalence fell mainly because of deaths from AIDS and the increasing use of condoms. Rather than critically parsing and addressing these arguments in the main text, Epstein relegates them to endnotes and chides other journalists for their "misleading" stories about the analyses. Another large study of five African cities with different HIV prevalences did not find that concurrency explained much of anything. It, too, is explained away in an endnote. (Editor's note: This study appeared in the endnotes in the galley of the book sent by the publisher to reviewers. In the book's final edition, the discussion was moved into the main text.)

Another of five African cities with different HIV prevalences did not find that concurrency explained much of anything. It, too, is explained away in an endnote.

There's a sobering coda to Uganda's success that was reported at last August's international AIDS conference, maybe too late for Epstein's book deadline: It's fragile. A large, multiyear study in the country showed an upswing in prevalence between 2000 and 2005. This resembles the drop and rise seen in many gay communities in the United States and Europe. People become fatigued by prevention campaigns, and, in communities that have access to anti-HIV drugs, there's also decreasing fear of the virus as funerals become less frequent and fewer emaciated people walk the streets. Until there's a safe and effective AIDS vaccine, which is still nowhere in sight, prevalence likely will rollercoaster just about everywhere.

Fortunately, new prevention strategies promise to come on line soon. Well-done trials recently proved that circumcision can reduce the risk of transmission by about 60 percent, and several novel studies now under way are investigating the efficacy of different drugs, microbicides, female diaphragms, and the targeting of people who recently became infected and account for a disproportionate amount of transmissions. Thanks to Epstein and the researchers she celebrates, there's also increasing awareness about the role of concurrent partnerships. But the cure for AIDS epidemics? That remains hard to see, if not wholly invisible.